SYMPOSIUM D

9:00 AM *D4-S1.1 (invited)
Photonics on Chip. (#1255) Michal Lipson, Carl B Poitras; Cornell University, Ithaca, New York, USA.

Photonics on chip could enable a platform for monolithic integration of optics and microelectronics for applications of optical interconnects in which high data streams are required in a small footprint. Using highly confined photonic structures we have demonstrated ultra-compact passive and active silicon photonic components with very low loss. The highly confined photonic structures enhance the electro-optical and non-linearities properties of Silicon. We demonstrated several GHz active components including high performance detectors, modulators and switches on silicon.

9:30 AM D4-S1.2
Probing Chalcogenide Microspheres. (#973) Christian Grillet, Shu Ning Bian, Eric C Magi, Benjamin E Eggleton; CUDOS, The University of Sydney, New South Wales, Australia.

Solid state microsphere resonators have been a subject of enormous interest in areas as diverse as sensing, cavity quantum electro-dynamics experiments, low-threshold lasers, spectroscopy and all optical switching [1]. Numerous applications have been achieved using amorphous glasses, like fused silica [2] or Er:Yb-doped phosphate glass [3], first because they are easy to manufacture and also because they can sustain morphology-dependant resonances (MDR) displaying high Q factors [4]. One of the disadvantage of these silica microspheres is that, compared to characteristic modal volume achievable in high index material shaped in a ring, disk or planar photonic crystal platform, the modal volumes in these microspheres are still several orders of magnitude higher. In this respect, Chalcogenide glasses are an attractive alternative to silica based material for these applications. They possess a relatively high refractive linear index (typically between 2.6 and 3) leading to a higher natural confinement, thus possibly lower modal volume. Depending on the composition, these glasses can also offer excellent transparency from 1.5 ?m to 20 ?m opening the prospect of high sensitivity chemical sensing operation in the mid-infrared (MIR). In addition to its linear properties, these glasses are known to exhibit several substantial advantageous non linear properties including high pure kerr-nonlinearity, and low two photon absorption [5]. As pointed out in ref [5], being a glass, the chalcogenides are a versatile platform that has already been exploited in bulk system, fibers, planar waveguides, planar photonic crystal structures and very recently in microsphere geometry. In this letter, we report a simple fabrication technique of chalcogenide microspheres and the characterization of these chalcogenide microspheres. Strong polarization dependant resonances are observed corresponding to coupling to MDR. Loaded Q factors of more than 20000 with a 3 dB transmission depth have been measured. The ability to couple to high Q chalcogenide microsphere modes opens up the prospect of a wealth of new science in both telecom and mid-infrared windows. It is expected that applications of chalcogenide microsphere can be as versatile as silica microsphere with the added advantage of the higher nonlinearity provided by the chalcogenide and the extra possibility of accessing the MIR window. [1] V. S. Ilchenko et al, IEEE Journal of Selected Topics in Quantum Electronics, 12 (1), 15-31 (2006). [2] M. L. Gorodetsky et al, J. Opt. Soc. Am. B, 17, 1051-1057 (2000). [3] M. Cai et al, Opt. Lett. 25, 1430-1432 (2000). [4] V. S. Ilchenko et al, IEEE Journal of Selected Topics in Quantum Electronics, 12 (1), 3-14 (2006). [5] V. G. Ta'eed et al, Opt. Express 15, 9205-9221 (2007).

9:45 AM D4-S1.3
Nano-Focusing of Surface Plasmons in Metallic Nano-Structures. (#1167) Dmitri K. Gramotnev¹, David F. P. Pile²; ¹Applied Optics and Nanotechnology Program, School of Physical and Chemical Sciences, Queensland University of Technology, Australia ; ²University of California Berkeley, USA.

Plasmon nano-focusing in metallic nanostructures offers a feasible resolution to one of the major goals in modern nano-optics, near-field scanning microscopy and nano-sensing, which is effective concentration and delivery of light energy with total spatio-temporal control into regions that are much smaller than the wavelength. In this presentation, adiabatic and non-adiabatic nano-focusing of localized surface plasmons in tapered metal rods, sharp wedges, tapered nano-gaps and V-grooves, nano-holes, etc. is reviewed and discussed. In particular, substantial slowing down of surface plasmons simultaneous with strong local field enhancement are demonstrated and analyzed theoretically. Rigorous and approximate methods of analysis are discussed for different structures, based on the finite-difference time-domain algorithm, finite element analysis, and geometrical optics (adiabatic) approximation (for weakly tapered structures). The results derived from the analytical and numerical approaches are compared. The main advantages and disadvantages of different nano-focusing structures are highlighted, including their comparison and optimization for achieving maximal possible local field enhancement. Links of nano-focusing to strongly localized plasmonic eigenmodes are demonstrated and analyzed. Physical limitations of plasmon nano-focusing are highlighted and discussed. Application possibilities of the considered structures with plasmon nano-focusing in near-field microscopy, new nano-sensor technology, effective coupling of light energy into plasmonic nano-circuits are also discussed.

10:00 AM D4-S1.4
Low Cost Nanoimprinted Polysiloxane Waveguides. (#1065) Ting Han¹, Steve Madden¹, Mathew Zhang¹, Robbie Charters², Barry Luther-Davies¹; ¹Laser Physics Centre, Research School of Physical Sciences and Engineering, The Australian National University, Australian Capital Territory, Australia ; ²Redfern Polymer Optics Pty. Ltd., Australia.

Nanoimprint lithography is gaining rapid acceptance in fields as diverse as microelectronics and microfluidics due to its high resolution and low cost. Both these properties are critically important for the fabrication of photonic devices, where cost is often the major inhibiting deplyment factor for high volume applications (eg Fibre to the Home). Using the micromolding capabilities of the technology, we report here on the use of nanoimprint to fabricate low cost planar waveguides in a polysiloxane polymer system capable of passing the stringent Telcordia environmental and reliability criteria. Low loss buried channel waveguides with core cross sections of 3x3 microns and a 3% refractive index contrast were fabricated on bare silicon wafers with a simple and fast three step process using a 100mm diameter polymethyldisiloxane stamp. The waveguides were patterned using an innovative "minimum fluid displacement" method which eliminated the residual films often seen either side of rib like features such as the waveguide cores, and which also produced very good dimensional control of the core itself regardless of the uncured spun core layer thickness. Thus this process also offers good manufacturing process tolerances. Stamp fabrication processes, the nanoimprint method itself, and the results of characterization of the resulting waveguides are presented showing the method to be a very promising route to fabricating low cost waveguide devices. Further, the technology holds the promise of patterning complete passive devices with waveguide gratings for example to yield low cost wavelength division multiplexing devices with no increase in production complexity or cost. Potentially the process can be scaled to a roll to roll scale to generate very low cost devices.

10:15 AM D4-S1.5
Growth and Characterisation of High Purity Twin-Free GaAs Nanowires. (#448) Hannah Jane Joyce¹, Qiang Gao¹, H. Hoe Tan¹, Chennupati Jagadish¹, Xin Zhang², Jin Zou²; ¹Electronic Materials Engineering Department, Research School of Physical Sciences and Engineering, The Australian National University, Australian Capital Territory, Australia ; ²The University of Queensland, Brisbane, Australia.

Semiconductor nanowires hold great potential as nanoscale building blocks for future electronic and optoelectronic devices. The direct band gap and high carrier mobility of the GaAs material system makes GaAs nanowires especially promising for nanowire based optoelectronic devices, such as lasers and photodetectors. GaAs nanowires may be grown in a scalable and flexible fashion, by metalorganic chemical vapour deposition (MOCVD) using Au nanoparticles as catalysts. Several challenges face the growth of high quality GaAs nanowires, in particular nanowire kinking, unintentional radial growth, intrinsic doping, and crystallographic defects, notably twins [1]. Device applications demand straight well aligned nanowires of uniform diameter, high crystallographic quality, excellent optical properties and controlled doping. Here we examine the growth conditions necessary to achieve GaAs nanowires of optimum quality. Nanowire properties were determined by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and photoluminescence (PL) measurements. First we examine the effect of group V flow rate, that is, the supply of As precursor species during MOCVD growth. Significantly we find that using a high group V flow reduces the incidence of crystallographic twin defects. This is possibly because As species reduce surface and interfacial tensions in the Au nanoparticle–nanowire system. High group V flows have a further advantage: reducing impurity incorporation, as revealed by PL studies. As group V flow rate is increased further, however, nanowire growth takes place in kinked and irregular directions. This places an upper limit on the group V flow rate that can be used. As an alternative, we explore growth rate as a means to control nanowire properties. Growth rate is increased by increasing flow rates of both group III and group V precursors, scaling these rates together. We find that increasing growth rate has three major advantages. First, this markedly reduces the density of crystallographic twin defects. Second, this reduces impurity incorporation. Finally, nanowires grown at a fast growth rate exhibit very uniform minimally tapered morphologies. This reduced tapering is especially desirable for devices such as nanowire lasers, where a uniform nanowire diameter should enhance the nanowire's performance as a resonant cavity. In summary, we find that excellent crystallographic and optical properties can be achieved if nanowires are grown at a fast growth rate, meaning high group III and group V precursor flow rates. References: [1] H. J. Joyce, Q. Gao, H. H. Tan, C. Jagadish, Y. Kim, X. Zhang, Y. Guo, and J. Zou, "Twin-Free Uniform Epitaxial GaAs Nanowires Grown by a Two-Temperature Process," Nano Lett., vol. 7, pp. 921-926, 2007.

MORNING BREAK 10:30 AM - 11:00 AM

11:00 AM D4-S2.1
The Roles of Surface Adsorption and Substrate Interactions on Surface Enhanced Raman. (#1163) Dimitri A Alexson, Stefan C Badescu, Orest J. Glembocki, S M Prokes, Ronald W Rendell; Naval Research Laboratory, Washington, DC, USA.

Surface enhanced Raman scattering (SERS) provides a detection method for picoliter or less quantities of molecules. However, wide deployment utilizing this promising technique continues to elude the chemical and biological sensor industry. Basic research is needed to more fully understand the relationship between the chemical being sensed, the probing light and the SERS substrate. A deeper understanding of the molecule-substrate complex will then enable the application of SERS as a highly sensitive and universal method for detection and identification of chemical and biological agents. The origins of the SERS mechanism have been widely studied and are generally accepted as understood. The emphasis has traditionally been placed on the optical properties of a few special metals and their support of surface plasmons at visible wavelengths. Consideration of the nature of the molecules being sensed is often dismissed and its effect on the SERS enhancement factor has generally been regarded as negligible. However, there is still a need to provide a satisfactorily complete model which addresses the often observed phenomena in which various adsorbed molecules exhibit weak or even no SERS response at all. The relative intensities of vibrational modes observed in SERS can depend strongly on the type of surface adsorption, such as chemisorption or physisorption, or as chemical bond type (covalent/noncovalent) and number of covalent bonds to the surface. Thus, in this experimental study the role of surface adsorption in SERS is investigated. A simple group of molecules was chosen to facilitate comparison with theoretical models. These molecules are based around the benzene ring and include benzene thiol and dithiols (SH end groups), benzene dimethyl thiol (SH and methyl groups), nitrobenzene and toluene. Experimental results with consideration towards surface bond strengths and reduction in degrees of freedom due to single and multiple surface bonds is presented and compared with model calculations. Their effect on the relative intensities and positions of observed vibrational modes observed in the SERS spectra are discussed. The relative stability and enhancement factor of SERS in the presence of nanostructures exhibiting strong and weak local electric fields will also be presented and discussed. We used both nanosphere arrays for weak SERS enhancement fields and nanowires which exhibit strong plasmonic coupling at the crossings for the high SERS fields in our work. Another aspect of SERS is the pervasive presence of the continuum background. The background continuum is not observed from either the metal nanostructures or the chemical species themselves alone, but always when the two are brought together. This simple observation emphasizes the need to understand the nature of the chemical and its relationship to the substrate. From our experimental and theoretical work, we can show that the presence of the continuum background can be ascribed to electronic interactions between the SERS nanoparticle and the adsorbing chemical species, which provide a vehicle for the excitation of molecules whose HOMO-LUMO gaps are significantly greater than the SERS excitation laser. Experimental and theoretical results will be presented exploring the relationship between bonding type and strength and SERS repeatability with respect to the nature of the background continuum. The impact of the chemical nature of the molecule-substrate complex on SERS will be also be discussed.

11:15 AM D4-S2.2
Comparison of Microfluidic Cavities Based On Chalcogenide and Silicon Photonic Crystals. (#958) Cameron Lesley Smith¹, Uwe Bog¹, Snjezana Tomljenovic-Hanic¹, Christian Grillet¹, Christelle Monat¹, Christian Karnutsch¹, Ross McPhedran¹, Benjamin Eggleton¹, Liam O'Faolain², Marcel Spurny², Tom White², Thomas Krauss²; ¹CUDOS, The University of Sydney, New South Wales, Australia ; ²School of Physics and Astronomy, University of St. Andrews, United Kingdom.

We demonstrate and compare microfluidic double-heterostructure cavities in photonic crystal slab waveguides based on silicon and chalcogenide glasses. The cavities are formed via highly localised fluid infiltration of select holes in the photonic crystal. This approach not only offers reconfigurability but is also freely post-processible. The comparison is made considering the different wetting properties, slab indices and lattice parameters between the two materials. Research based on photonic crystal slab (PCS) cavities is a rapidly growing field. Strong light confinement and extension of light-matter interaction endow PCS cavities to be attractive options for a diversity of optical devices like low-threshold lasers, optical switches, channel drop filters and optical sensors. Cavities are often achieved by realising a local "defect" into a PCS during its fabrication, for example a double-heterostructure [1]. A major drawback for such PCS cavities lies in the necessity of high fabrication accuracy. Recent work has shown that PCS cavities may be formed after this process by infiltrating select holes with a suitable fluid [2]. In this paper we present microfluidic double-heterostructure cavities in PCS waveguides based on both silicon and chalcogenide glasses. We use highly selective fluid infiltration instead of a complex nanometre-scale alteration of the PCS's geometry, resulting in a local change of the effective index by approximately 1% in the PCS. The infiltration process is possible after fabrication and the resulting cavity is highly reconfigurable due to the inherent mobility of fluid. The cavity may be tuned by choosing fluids of different refractive indices or by adjusting the width of the infiltrated PCS region. Theoretical considerations have shown that very high Q-factors approaching 106 in silicon and 105 in chalcogenide glasses may be obtained in such geometries [3]. We experimentally characterise the microfluidic double-heterostructure PCS cavities in both silicon and chalcogenide glasses via evanescent coupling from a tapered optical fibre. Comparisons are made between the results of the cavities formed in the two different materials, taking into account their different wetting properties, slab indices and lattice parameters. [1] B Song et al, Nat. Mater. 4, 207 (2005) [2] C Smith et al, App. Phys. Lett., 91, 121103 (2007) [3] S Tomljenovic-Hanic et al, Opt. Express, 14, 25 (2006)

11:30 AM D4-S2.3
Polarization-Induced Giant Enhancement of Light Transmission through a Pyramidal Probe. (#96) Seong Soo Choi, Sun Moon University, Republic of Korea.

There have been tremendous interests about the gigantic enhancement of optical transmission intensity through the nanostructured metal aperture due to possible applications such as local optical communications, next generation optical storage devices, and nano-bio sensor technology. The conventional nearfield optical probes, such as metal-coated fiber probe and even microfabricated pyramidal probe, have shortcomings of very low transmission intensity ranging from 10-3 to 10-6 . The development of the nearfield nano-probe with greater output intensity would be necessary. Previously, the enhancement of optical intensity through metal-coated pyramidal probe surrounded by square-type periodic groove has been reported.[1,2]. In this report, the gigantic optical transmission upto thousand times fold increase for the nanostructured periodic grooves surrounding the Al metallic circular aperture on the apex of the pyramidal probe has been observed. This huge enhancement has been attributed to P-polarization of the incident beam resulted in backward emission from the subwavlengthsize aperture. References: [1] S.S. Choi, D.W. Kim, M.S. Joo, M.J. Park, et al, EOS Topical Meeting on Molecular Plasmonic Devices, April 27-29, 2006. Engelburg, Switzerland. [2] S.S. Choi, D.W. Kim, M.J. Park, et al, 3rd International Conference on Surface Plasmon Photonics, June 17-22, Dijon, France..

LUNCH 12:30 PM - 2:00 PM

2:00 PM *D4-S3.1 (invited)
Membrane Photonic Crystals Based on III-V Semiconductors: Potential for All Optical Switching, Light Matter Interaction and Slow Light. (#1233) Alfredo De Rossi¹, Sylvain Combrié¹, Quynh Vy Tran¹, Chad Husko²; ¹Thales Research and Technology, France ; ²Thales Research and Technology and Columbia University, France.

Membrane photonic crystals are thin layers of semiconductor suspended in a low index medium (e.g. air) with a two dimensional periodic pattern of holes. These structures are alternative to microrings [1] and have been demonstrated to be ideal to provide strong optical confinement based on the principle of Bragg reflection. High-Q factor microresonators (~2 M) with unparalleled modal volume (~0.1 fl) have been demonstrated [2], which makes these structures very attractive for fundamental investigation of light matter interaction as well as for a variety of applications (novel lasers sources, sensors, all optical switching and photonic circuits). The potential for nonlinear optics of PhC has been investigated theoretically [3] and important results have been achieved (low-energy optical bistability, all-optical switching and dynamical control of the cavity lifetime) [4]. As for Si-based micro-ring [5], the nonlinear process involved is two-photon absorption (TPA) followed by carrier-induced refractive index change, with response time of about 100 ps. These achievements rely on very high quality processing of Silicon on Oxide (SOI) substrates. Processing of PhCs based on III-V semiconductors allows not only the inclusion of active structures (Quantum dots or Quantum Wells) into high quality cavities [6], but also the enhancement the fast kerr nonlinearity below the half band gap, in order to suppress nonlinear absorption [7]. Kerr based switching is also pursued with Chalcogenide materials and the demonstration of high-Q PhC resonators has been reported recently [8]. We have developed a PhC technology on GaAs-based membranes. A figure that benchmarks the quality of processing of PhC structures is the Q-factor of microcavities. This reveals that our technology is almost comparable to that of Si-based PhCs, as we demonstrated microresonators with very high Q-factors (~700000) [9]. However, disorder induced losses, in particular backscattering, and thermal effects, are serious practical issues needing to be better understood and fixed. We have reported ultra low power bistability in PhC microcavities [10] and we are investigating fast thermal dynamic. We have developed a new approach for understanding disorder-induced losses [11]. In this presentation, these issues will be discussed in relationship with applications for all optical switching. References [1] J. E. Heebner et al., Opt. Lett. v. 29, p. 769 (2004); [2] Y. Takahashi et al., Opt. Expr. vl. 15, p. 17206 (2007); [3] M. Soljacic et al., Nature Mat. v. 3, p. 211 (2004); [4] T. Tanabe et al., Nature Photonics v. 1, p. 49 (2007) ; [5] V.R.Almeida, Nature v. 431, 1081 (2004); S. Preble, et al, Nature Photonics v. 1, 293 (2007) [6] O. Painter et al., Science vol. 284, 1819 (1999) ; T. Yoshie et al., Nature vl. 432, 200 (2004) ; A. Badolato et al. , Science, v. 308, p.1158 (2005) ; H. Park et al. Science v. 305, p. 1444 (2004) ; [7] H. Oda et al., Appl. Phys. Lett, vl. 90, p. 231102 (2007) ; [8] Y. Ruan et al., Appl. Phys. Lett. vl. 90, p.071102 (2007); [9] E. Weidner et al ., Appl. Phys. Lett. vl. 89, p. 221104 (2006); S. Combrie' et al., subm. to Opt. Lett. ; [10] E. Weidner et al ., Appl. Phys. Lett. vl. 90, p. 101118 (2007); [11] S. Combrie', Appl. Phys. Lett., v. 90, p. 231104 (2007);

2:30 PM D4-S3.2
Realisation of Three-Dimensional Woodpile Photonic Crystals Working in the Visible Wavelength Range. (#483) Jiafang Li, Baohua Jia, Min Gu; Centre for Micro-Photonics and Centre for Ultrahigh-bandwidth Devices for Optical Systems (CUDOS), Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia.

Photonic crystals (PhCs) are periodical micro-structures which have been intensively studied as a promising candidate for integrated optical devices. As a direct laser-writing method, two-photon polymerisation (2PP) has been employed successfully in the fabrication of arbitrary functional two-dimensional (2D) or three-dimensional (3D) nano-structures. In 2PP, a photosensitive resin is polymerised by irradiation with tightly focused femtosecond laser pulses (~ 100 fs) and the size of the polymerised volume can be controlled by the variation of the laser power and irradiation time. The limitation of fabricated structures (~100 nm) is determined by the optical limit of the fabrication system, and by the polymerisation properties of the resin as well, which makes it difficult to fabricate 3D PhCs working in visible wavelengths. Compared with those pre-treatments, here, we show that the limitation could also be improved by a post-process. Through a post-thermal treatment, the features of fabricated structures can be further reduced by more than 50%. Meanwhile, the surface roughness of polymerised structures is also improved. By combining the threshold fabrication technique with this post-thermal treatment, 3D woodpile PhCs with stop gaps in the visible wavelength range have been successfully realised, which provides a constructive platform for applications of 3D woodpile PhCs in visible wavelengths. Moreover, compared with the conventional 2PP fabrication technique, this method provides a useful option for producing smaller templates for the fabrication of high refractive index inverse 3D woodpile PhCs.

2:45 PM D4-S3.3
Photo-Induced Double-Heterostructure Cavities in Chalcogenide Glass Photonic Crystals. (#1045) Michael Whalen Lee¹, Christian Grillet¹, Snjezana Tomljenovic-Hanic¹, Cameron L C Smith¹, Darren Freeman², Steve Madden², Barry Luther-Davies², Benjamin J Eggleton¹; ¹The University of Sydney, New South Wales, Australia ; ²Laser Physics Centre, Research School of Physical Sciences and Engineering, The Australian National University, Australian Capital Territory, Australia.

Abstract: We present a first demonstration of a double-heterostructure type photonic crystal (PC) cavity formed by modifying the refractive index of the PC locally using the photosensitivity of the chalcogenide glass. High-Q cavities in 2-dimensional planar photonic crystals are of interest for applications such as nonlinear all-optical switching, microfluidic sensing and quantum information processing [1]. To date, some of the highest experimentally demonstrated Q-factors in a PC cavity have been obtained in double-heterostructure type cavities [2]. These cavities confine light by the 'mode gap' effect, which is caused by modifying a short section of a 'W1' waveguide in a way that locally increases the effective index of the waveguide. Typically this has been achieved by geometric modification of the PC lattice, e.g. increasing the lattice period of a short section of the waveguide, however, other methods have been demonstrated, such as fluid infiltration of the air holes of the PC [3]. In this work we present a first demonstration of a double-heterostructure type cavity formed by local refractive index modification of a photosensitive chalcogenide glass PC, as proposed by Tomljenovic-Hanic et al [4]. We were able to measure the cavity formation in situ by using a tapered optical fibre coupled evanescently to the PC and can present results which show the growth and evolution of the cavity resonance during the photosensitive process. This technique has the advantage that there is some control over the final cavity properties since the cavity is monitored during its creation. The photonic crystal samples used for this work were 'W1' waveguides, i.e. a single row of holes missing from a hexagonal lattice of air holes in a thin membrane of chalcogenide glass. The glass composition used in this work was AMTIR-1 (Ge33As12Se55) and the fabrication was performed by focused ion beam (FIB) milling. When the photosensitivity of this material was characterized, the refractive index was found to decrease when exposed to light at 633nm. The desired refractive index profile to form a double-heterostructure cavity is for a small region of the waveguide and photonic crystal to have a higher refractive index than the rest of the structure. In order to create this index profile a photomask was used to block the exposure light from the cavity region, leaving an approximately ~3?m wide unexposed stripe. The formation of the cavity was monitored in situ using an evanescent coupling technique and these measurements clearly demonstrate the formation of a cavity. In conclusion we present an encouraging first demonstration of a PC cavity which was created using photosensitivity. References 1. S. Noda, "Recent Progresses and Future Prospects of Two- and Three-Dimensional Photonic Crystals," J. Lightwave Technol. 24, 4554-4567 (2006) 2. T. Asano, B. -S. Song, and S. Noda, "Analysis of the experimental Q factors (~ 1 million) of photonic crystal nanocavities," Opt. Express 14, (2006) 3. C. L. C. Smith, D. K. C. Wu, M. W. Lee, C. Monat, S. Tomljenovic-Hanic, C. Grillet, B. J. Eggleton, D. Freeman, Y. Ruan, S. Madden, B. Luther-Davies, H. Giessen, and Y.-H Lee, "Microfluidic photonic crystal double heterostructures", Appl. Phys. Lett. 91, (2007) 4. S. Tomljenovic-Hanic, M. J. Steel, C. Martijn de Sterke, and D. J. Moss, "High-Q cavities in photosensitive photonic crystals," Opt. Lett. 32, (2007)

3:00 PM D4-S3.4
Fabrication and Optical Properties of Periodical Structures Based on a Water-Developable and Tunable La_0.7Sr_0.3MnO₃ Resist. (#494) Ming-Chung Wu, Sharon Chen, Chih-Min Chuang, Yi Chou, Yang-Fang Chen, Wei-Fang Su; National Taiwan University, Taiwan.

Recently, considerable interests have been focused on the light modulation using periodic structure such as photonic crystal. Yablonovitch and John first described photonic crystals in 1987. The structures can exhibit photonic band gaps, similar to the electronic band gaps of materials. Therefore, one can control the propagation of light by restricting its allowable directions at certain frequencies or localizing light in specific areas. The technology is expected to have numerous applications in optical communication. Many methods have been developed to fabricate the photonic crystal, such as multilayer lithography, multibeam holographic lithography, self-assembly, step and flash imprint lithography, electrochemical deposition, etc. Among all, electron beam lithography has become the most common method to fabricate 2D photonic crystal and nanoscale patterns because of its ability to construct high precision structure. The formation of photonic band gap, which can be used to guide the propagation of light as well as to enhance spontaneous emission, is due to the periodically varying refractive indices. Thus, an electron beam patternable metal oxide with high refractive index will be useful for this process. The nanostructure fabrication of metal oxide material generally starts with selective etching or template growth on the pre-patterned resist and then lift-off. While these approaches lack the ability to control the construction of the nanostructure accurately, using electron beam to generate exact nanopatterned metal oxides like ZnO, TiO2 etc can be much easier. The methods and materials mentioned above all generate negative patterns. A zwitter resist refers to a resist that can exhibit both positive and negative properties depending on the applied electron beam dosage. This type of resist possesses both positive and negative patterning capabilities and will benefit the direct writing technology of electron beam. In addition, the solvents used in common resist developing process are often volatile and toxic and thus contribute to health hazard and environmental pollution. Solvents even add up the cost of lithography processing. Many researches are directed to build multifunctional resists with precise nanostructure and at the same time reduce the process hazards and pollution. In this experiment, the electron beam resist was prepared by dissolving 8.58 wt% of lanthanum nitrate (La(NO3)3.6H2O, Acros, 98 %), strontium nitrates (Sr(NO3)2, Fluka, 98 %), manganese nitrates (Mn(NO3)2.4H2O, Fluka, 97 %) and 1.75 wt% polyvinyl alcohol (PVA, Acros, 88 %, 22000 g/mol) in water with a molar ratio of La : Sr : Mn = 0.7 : 0.3 : 1.0. The precursor solution was stirred for 48 hours at 50oC. After the precursor solution was filtered by syringe filters (0.22um), the precursor solution was spin coated at 3000 rpm for 90 seconds to give a nominal thickness of about 200 nm. The resist film appears to be very smooth with a root-mean-square of 1.02 nm. The thickness of the water-developable La0.7Sr0.3MnO3 resist coated on the substrate (indium tin oxide conductive glass or silicon wafer) was measured directly by an alpha-stepper (Veeco, Tektak3). High-resolution nanolithography was performed by using a Hitachi ELS-7500EX machine to write the specific patterns across a 150 x 150um field with a 2.5 nm beam step size. The electron beam writter was operated at 50 kV with a probe current of 1.0 nA. A sample containing a 3 x 3 array field was irradiated with a starting dose time of 1us, then with additional dose increment of 0.01, 0.1 and 1us per field. The deionized water was used to develop La0.7Sr0.3MnO3 resist at 25oC for 30 seconds. The refractive indexes of the La0.7Sr0.3MnO3 thin films sintered at different conditions were evaluated using a spectral microreflectometer (Mission Peaks Optics, MP100-M) equipped with an optical microscope. The patterned La0.7Sr0.3MnO3 samples were measured by atomic force microscopy (AFM, Digital Instruments, Dimension-3100 Multimode) for surface morphology and roughness, and the microstructures of the samples were studied by both field-emission scanning electron microscope (FE-SEM, Elionix, ERA-8800FE, Japan) and confocal microscopy. The confocal microscopic images of the patterned La0.7Sr0.3MnO3 samples were measured by confocal fluorescence microscopy. The Argon ion laser (wavelength 488 nm) was used to excite the patterned La0.7Sr0.3MnO3 samples through a 100x Nikon plane objective (NA~0.9). A single photon counting photo multiplier tube (PMT) detector was used to detect the intensity of the reflective laser light. The reflectance of the patterned La0.7Sr0.3MnO3 samples were studied using the transmittance mode of the same spectral microreflectometer. Unpolarized light was focused on the composite film on the glass substrate at a spot size < 30 um to measure the interference between the incident and reflected light with wavelengths ranging from ultraviolet to near infrared (250~1000 nm). In this study, we have fabricated unique periodic structure with different optical properties in visible range using water-developable La0.7Sr0.3MnO3 electron beam resist. The La0.7Sr0.3MnO3 resist can be developed under a nontoxic and environmentally friendly manner using pure water. Additionally, the resist is capable to exhibit both positive and negative resist behaviors depending on the electron beam dosage. Thus, this special characteristics are used to fabricate and tune the periodic structure of thin films to control their optical reflectance in the wavelength of 300 nm to 800 nm with one fixed design electron beam pattern (i.e. without changing the geometries and lattice constants of the periodic structures) by simply changing the electron beam dosage.

AFTERNOON BREAK 3:30 PM - 4:00 PM

4:00 PM *D4-S4.1 (invited)
Heteroepitaxial Magneto-Optical Photonic Crystals. (#871) Alexander M Grishin, Department of Condensed Matter Physics, Royal Institute of Technology, Kista, Sweden.

We report processing and characterization of epitaxial magneto-optical (MO) garnet films and heteroepitaxial all-garnet MO photonic crystals based on completely substituted bismuth iron garnet Bi3Fe5O12 (BIG) which shows the record value of Faraday rotation (FR) as high as &theta = -8.4 deg/&mum @633nm and a peak value of -28 deg/&mum @537nm. We use pulsed laser deposition and rf-magnetron sputtering techniques to grow heteroepitaxial 1D photonic crystals which compose of &lambda/4 garnet layers alternating highly gyrotropic BIG and MO-passive highly transparent rare earth gallium garnets: Gd3Ga5O12, Sm3Ga5O12, and novel La3Ga5O12. At the resonance wavelengths 750 (980) nm, Bi3Fe5O12/Sm3Ga5O12 photonic crystals demonstrate specific FR &theta = - 20.5 (- 7.3) deg/&mum and MO-quality factor Q = 2|&theta|/absorption = 66 (43.6) deg that are the highest MO-photonic crystal performance achieved so far. Respectively, this is 470 (810) % and 31 (190) % enhancement compared to a single layer BIG. Using atomic layer deposition we fabricate Bi3Fe5O12/Gd3Ga5O12 superlattices with a strong perpendicular magnetic anisotropy. They enable latching type (non-volatile) MO-switching. 2.5 &mum thick Bi3Fe5O12/Gd3Ga5O12(3:2) film at 678 nm shows FR = 2.8 deg, transmittance 82%, 92% squareness of magnetization loop, saturation and coercive fields as low as 56 and 25 Oe, respectively. Nanostructured garnets were used to build MO-visualizer, current driven MO-display and have been integrated with glass substrates. We provide an assessment of magneto-optical photonic crystals for optical data recognition, processing and storage, color filtering, bandwidth control as well as their integrability with gain materials and lasing crystals.

4:30 PM D4-S4.2
Fabrication of Nickel Centers in Diamond for Quantum Optical applications. (#275) Igor Aharonovich, Alastair Stacey, Chunyuan Zhou, Jean-Francois Roch, Steven Prawer; School of Physics, The University of Melbourne, Parkville, Victoria, Australia.

Practical triggered single photon sources are of interest due to their potential usage as building blocks in quantum optics and particularly in quantum cryptography applications. Recent advances in diamond materials science and fabrication have raised the possibility for the use of diamond in quantum information processing and integrated optical devices. One of the unique features of diamond is the occurrence of stable, very bright, optical centers which can act as single photon sources. The Nitrogen-Vacancy complex is one example of such an optical center and has been subject to intense research since its highly attractive quantum properties (including room temperature decoherence times of nearly 0.5ms) have been identified. Nevertheless, the properties of the bulk diamond matrix are such that other impurities are also expected to give rise to optical centers whose properties might exceed those of nitrogen vacancies, particularly for applications in quantum key distribution. A good example of such center is the nickel nitrogen (NE8) defect in diamond which displays very narrow lines in the photoluminescence spectrum. However, the control over the efficient formation of these centers in diamond has not yet been achieved. In this work we present results for the controlled formation of various nickel based optical centers in diamond with a controlled spatial resolution. Three main routes were employed to form the centers. The first is the incorporation of nickel during the growth of chemical vapor deposition (CVD) diamonds. In the second we employ direct ion implantation of nickel into already deposited individual diamond nanocrystals. Thirdly, we implant nickel into high pressure high temperature (HPHT) single crystal diamond. The first result which was achieved is a controlled formation of high quality individual CVD nanodiamond crystals. It was found that under certain conditions the diamonds are well faceted and the optical characterization does not reveal any impurity incorporated during the growth. In order to study the influence of the crystal size on efficient creation of nickel centers, different sizes as well as different morphologies of individual diamond crystals were synthesized. Secondly, a photoluminescence study of the nanodiamond crystals after incorporation/implantation of nickel shows a forest of sharp peaks at the IR region of the photoluminescence spectrum (700-900nm). Furthermore, it was found that most of the centers can be pumped by lasers very far from the zero phonon line resonance. . The photon statistics of the centers, particularly whether the centers are emitting single photons, was studied both by excitation with continuous and pulsed laser sources. The second order correlation function of the excitation emission of an individual diamond crystal with a single nickel defect revealed a dip at t=0 delay, indicative of a single photon emission.

4:45 PM D4-S4.3
A Prototype Radiation Detector Based on Multi-Walled Carbon Nanotubes. (#537) Antonio Ambrosio¹, Michelangelo Ambrosio¹, Giuseppina Ambrosone², Viviana Carillo¹, Ubaldo Coscia², Valentina Grossi³, Pasqualino Maddalena², Maurizio Passacantando³, Eugenio Perillo², Adelaide Raulo², Sandro Santucci³; ¹CNR-INFM CRS-COHERENTIA and I.N.F.N., Italy ; ²I.N.F.N. and Dipartimento di Scienze Fisiche, Università di Napoli Federico II, Italy ; ³Dipartimento di Fisica, I.N.F.N. and CNR-INFM, Università dell'Aquila, Italy.

The detector we realized is constituted of Multi-Walled Carbon Nano Tubes (MWCNTs) growth in between two comb-like electrodes made of platinum, deposited by sputtering on a sapphire substrate. Platinum microstrips are 100 microns interspaced. Employing sapphire substrate in this prototype guarantees the absence of any electrical or optical contribution to the photo-signal from other then the nanotubes layer. Carbon Nanotubes are grown between the platinum microstrips by means of Chemical Vapour Deposition (CVD) into an ammonia rich chamber at the temperature of 500 Celsius degrees. The growth of CNTs is chemically assisted by Nickel nano-drops working as catalyst for the process. The diffusion of nickel on platinum guarantees the absence of catalyst particles directly on the electrodes and the growth of CNTs only on the substrate in between the strips. In the experimental configuration employed, a drain voltage is applied to one of the electrodes while the photo-signal due to light illumination is collected through the other electrode. These signals can be then easily observed by means of an oscilloscope close on its load resistance of 50 ohm without any further amplification. For this preliminary analysis the drain voltage has been kept lower than 25 V in order to prevent the system from eventual damages due to the electrical field in between the 100 microns interdigitated electrodes and to keep the sample characteristics as stable as possible. In our investigation we used pulsed laser beams originated by means of a Nd:YAG laser, > 10 ns pulse duration, 10 Hz repetition rate. We then used optical harmonic separators and dielectric mirrors mounted outside the laser in order to have, time by time, three different beams of adjustable energy and at three different wavelengths, 1064 nm, 532 nm and 355 nm (respectively fundamental, second and third harmonic of the neodymium laser). By integrated the signals acquired using the oscilloscope over the time interval monitored and dividing by the 50 ohm load resistance, we estimated the amount of photo-charge generated in the device by laser illumination. Improvement of sensitivity towards UV wavelengths has been observed reflecting the shape of the absorbance spectrum of the material obtained by means of an UV/NIR spectrometer. What we found is reasonable because, despite the trend of commercial photo-detectors, our prototype shows higher sensitivity corresponding to higher values of photon energy, i.e. lower wavelengths.

5:00 PM D4-S4.4
Multi-band and Broad-band Infrared Detectors Based on Low-Dimensional Quantum Structures. (#193) Sumith V Bandara, Sarath Gunapala, David Ting, John Liu, Cory J Hill, Jason M Mumolo; Jet Propulsion Laboratory, Pasadena, California, USA.

The III-V semiconductor alloy based Quantum Well Infrared Photodetector (QWIP) and Quantum Dot Infrared Photodetectors (QDIP) are excellent candidates for the development of large format, multi spectral focal plane arrays (FPAs) due to its mature fabrication technologies and inherent properties such as wavelength tailorability. Flexibility in many design parameters of these detectors allow tuning and tailoring the spectral shape according to application requirements, specifically for spectral imaging instruments. These technologies also permit vertical or in-plane integration of detector stacks sensitive in different IR bands. Each stack absorbs photons within the specified wavelength band, allowing other photons to transmit through permitting multiband detection. The key design parameters, including quantum well width, barrier height/ thickness, carrier doping density, and the number of periods of the absorption quantum well layers, can be optimized to deliver customized large format imaging arrays meeting unique requirements. Some of our recent work include a simultaneously readable, pixel co-located mid- and long-wave infrared dual-band FPA, a near and mid infrared FPA, a 2x2 super pixel four-band FPA , a broad-band FPA with graded wavelength response across the array, and a polarization sensitive FPA.

5:15 PM D4-S4.5
Exotic Optical Antenna Effects in Semiconducting Nanowires. (#1228) Peter C. Eklund, Jian Wu, Qiujie Lu, Humberto R. Gutierrez; Department of Physics and Materials Science and Engineering, The Pennsylvania State University, USA.

We have observed a series of novel antenna effects in the response of individual single crystal GaP nanowires (NW) to optical radiation. Our results will be seen to strengthen the platform from which electro-optic nanowire devices can be launched. Even though the diameters of these nanofilaments are too large (d>30 nm) to produce new physical properties stemming from the quantum confinement of electrons and phonons, they are not too large to escape the interesting consequences of photon confinement. To study these confinement effects, we have used polarized Raman and Rayleigh back scattering from individual NWs in a microscope-based spectrometer. Some surprises were found: (1) long GaP NWs behave as a perfect optical dipole antenna for diameters d<40 nm. (2) the symmetry of the Raman scattering from optical phonons predicted for the macroscopic sample suffers an apparent breakdown, (3) as the nanowire becomes shorter the scattering efficiency exhibits increasingly non-linear optical behavior, and (4) the tips of the nanowire are found to be scattering "hot spots".

D4-S5.2
Synthesis of TiO₂ / Polymer Composite Photochromic Materials by Sol-Gel Process. (#784) Dae-Girl Lee, Hyo-Jin Oh, Hyo-Sang Choi, Yong-Sung Choi, Yeong-Min Kim, Gyung-Soo Jeon, Sun-Jae Kim; Sejong University, Republic of Korea.

Photochromic materials are widely used as smart windows and reflective mirrors because of simply changing the colors by light irradiation without specific electrical equipment. The conventional photochromic thin films using polymers or transition metal oxides are merely depend on light reflection not absorption. However, in this study, we presented new preparation method for light absorption photochromic materials by sol-gel process. In order to prepare photochromic materials, 5 ml of 4.67 M TiOCl2 aqueous solution was mixed with 12 ml of N-N Dimethylformamide(DMF). After that, the solution was stirred for 24 hours at room temperature to control hydrolysis reaction. Finally gelated TiDMF was obtained after heat treatment for 24 hours at 70 Celsius. Prepared gel was exposed 3 hours in UV light and analysed the color changes as function of time and wavelength of light using colorimeter. The crystal structures and micro images of dried gel were analysed after pulverization using XRD and SEM, respectively. As the result, when UV light was irradiated under 400nm wavelength, the transparent gel was changed into dark blue color. Also, the color changed gel was turned transparent again after appropriate time.

D4-S5.3
Dry Etching of Amorphous As₂S₃ Films in CHF₃ Plasma. (#340) Duk-Yong Choi, Steve Madden, Anrei Rode, Rongping Wang, Barry Luther-Davies; Laser Physics Centre, Research School of Physical Sciences and Engineering, The Australian National University, Australian Capital Territory, Australia.

A chalcogenide glass (ChG) is one containing the chalcogen elements (S, Se or Te) as a substantial constituent and these are covalently bonded to network formers, Ge, As, Sb, or Si. ChG films are widely used in data storage media and non-volatile random access memories, but they also are regarded as good candidates for integrated nonlinear optic devices using nanowire waveguides due to their high linear and nonlinear refractive indices and low linear and nonlinear loss. However to create nanowires with sufficiently low optical losses, surface roughness has to be carefully controlled to prevent excessive scattering at the waveguide surfaces. In this study we report the dry etching characteristics (the etch rate, the selectivity, the edge profile, and the etched surface roughness) of amorphous As2S3 film in CHF3 plasma and developed a suitable patterning condition for compact waveguides devices. The chemical reaction with fluorine radicals is the main removal mechanism in As2S3 film etching. Photo-resist mask erosion was suppressed due to enhanced polymer deposition so that high etch selectivity and small etch bias of patterns was accomplished. CHF3 gas flow rate affects significantly the etched profile and surface roughness as well as the etch rate of As2S3. The isotropic profile becomes vertical with the flow rate due to the polymer sidewall passivation. Passivation also helps to make a smooth etched sidewall because it prevents the phase separated As2S3 films from differential chemical attack by F-atoms; otherwise grainy etched surface would come. However, excessive polymer deposition on the film surface at high flow rate results in positive-sloped sidewall and the micro-masks which result in rough etched surface. All the observed etching behaviours can be explained by the variation of the relative densities of fluorine atom, polymer precursors, and ions in the plasma, which are dependent upon the applied process parameters.

D4-S5.4
Influence of Titanium Adhesion Layer on the Light Transmittance through a Nano-Aperture. (#205) M.J. Park, V. Jha, O Suwal, D.W. Kin, S.S. Choi; NRL, Sun Moon University, Republic of Korea.

There have been tremendous interests about enhanced light transmittance through cylindrical nano-aperture due to various applications such as nearfield optical lithography, nearfield optical trapping, etc. The oxide pyramids have been fabricated through conventional microfabrication techniques including photolithographic pattern transfer, alkaline solutions Si wet etching. The thin Ti film deposition has also been carried out to provide the smooth Al surface on the top as wetting layer between the silicon oxide and the deposited aluminum thin film. In addition, the nano-periodic structure with the aperture has been fabricated using FIB system. The light transmittance between the Al deposited nano-aperture without Ti wetting layer and with Ti wetting layer have been evaluated. We have previously reported hugh enhacement of the transmitted light intensity through the Al coated nano-aperture on the pyramid.[1,2] For addition Ti wetting layer, the reduced light transmittances from the aperture have been measured. This could be attributed to less surface plasmon coupling between the surface plasmons bounded to the Al surface and the Ti surface. This can provide the evidence for surface plasmon polariton contribution to the enhancement of light transmittance through the metallic subwavelength size aperture in the visible range. References: [1] S.S. Choi, D.W. Kim, M.S. Joo, M.J. Park, et al, EOS Topical Meeting on Molecular Plasmonic Devices, April 27-29, 2006. Engelburg, Switzerland. [2] S.S. Choi, D.W. Kim, M.J. Park, et al, 3rd International Conference on Surface Plasmon Photonics, June 17-22, Dijon, France..

D4-S5.5
Characterization and Modeling of Photosensitivity Properties of SnO₂ Thin Film Sensors Fabricated by Spray Deposition Technique. (#808) Marcio Fontana, Nilo Lima Matias, Aiese Cruz Barros, Fabiano Fragoso Costa; Departamento de Engenharia Elétrica, Federal University of Bahia, Salvador, Brazil.

Tin oxide films have interesting structural and electronic properties which inspire a number of new and useful applications for electronic gas sensors, flat display devices, thin-film transistors, transparent electrodes and photovoltaic cells. A diversity of processes have been used to prepare SnO2 coatings, such as sol-gel, sputtering, chemical vapor deposition (CVD), and spray deposition technique, which was applied to this work. The experimental set-up consists of a reservoir of liquid Sn solution that feeds by gravity a jet gas nozzle. The nozzle is induced by the flow of nitrogen through a small orifice to the atmosphere. Control valves were placed to independently adjust the nitrogen and the Sn solution flow rates. The substrates were mounted horizontally over a steel hot-plate placed below the jet nozzle in order to receive an uniform spray coating. A 0.2M solution of pentahydrated stannic chloride (SnCl4.5H2O) in ethanol (C2H5OH) was used in the feed reservoir. Nitrogen flow was kept at 7 l.min-1 at 1520 Torr pressure and the solution spray rate was around 20ml.min-1. Deposition temperatures, measured by a chromel-alumel thermocouple, were controlled via the power supplied to the hot-plate, and were set in the range 523-723 K, corresponding to deposition rates of about 0.4-4.6 nm s-1, respectively. Also, some remarkable physical properties of the SnO2 film were investigated in this work. For instance, its conductivity behavior when exposed to visible light. For this purpose, a tin dioxide film was disposed in a chamber at atmosphere oxygen concentration and room temperature. Its resistance was measured when a light source was turned on and off over a fixed period of five minutes. This experiment was performed during a few months. On the first week, one has observed that the normalized resistance reduced by 54,7% of the initial value when the light was on. After 2 months, the resistance changed to 35,6% under the same conditions, and after 48 months the resistance reduced only by 0,5% of the initial value. These results showed that the SnO2 film can be used to detect light and that its photosensitivity decays over time due to the high oxidation surface and/or native oxide. Moreover, we proposed a mathematical model to characterize the tin dioxide films lifetime when submitted to O2 at atmosphere levels. An experiment using SnO2 films with the same deposition parameters mounted in a chamber under vacuum was carried out to investigate the oxidizing effect. Finally, morphological data obtained by atomic force microscopy (AFM) and results from Raman spectroscopic analyses of the samples will also be presented and discussed for the full version of this paper.

D4-S5.6
Substrate Effects in Surface-Enhanced Raman Spectroscopy Using Metal and Metal/Dielectric Nanowires Composites. (#727) Orest J. Glembocki¹, Ronald W. Rendell¹, S M Prokes¹, Dimitri A. Alexson¹, Michael A. Mastro¹, Anqi Fu²; ¹Electronic Science and Technology Division, Power Electronics Branch, Naval Research Laboratory, Washington, DC, USA ; ²University of Maryland, USA.

Surface enhanced Raman scattering (SERS) has been the subject of intense study for many years. Recently it has been shown that Ag coated Gallium oxide (dielectric) nanowires exhibit significant SERS enhancements due to hot spots formed at the crossings of the nanowires. Enhancements of 7 orders of magnitude have been achieved for DNT. Despite this work, the role of the substrate that the nanoparticles are applied to has been ignored. In this study, we show that the SERS from the nanoparticle contact with the substrate is significant and cannot be ignored. We have performed finite element modeling of Ag and Ag coated dielectric nanowires placed on dielectric substrates and isolated in air. We find that placing cylindrical nanoparticles on a substrate creates a large density of enhancement in the regions where the nanowire contacts the substrate. The SERS enhancement from these contact points is 3-4 orders of magnitude higher than from the surfaces of the isolated nanowires. These effects are so strong that for isolated nanowires on a substrate, the SERS enhancement rivals that of hot spots that are formed by the coupling from crossed nanowires or closely spaced nanowires. The simulations indicate that a similar effect will also be present in any spherical geometry. Experimental SERS mapping of various crossed and isolated Gallium oxide and Gallium nitride nanowires exposed to saturation coverages of benzene thiol shows that nanowires in contact with the substrate have SERS that is several orders of magnitude larger than from nanowires that are not in contact with the substrate. These results show that for any plasmonic effects, the substrate on which the nanoparticles are placed plays a significant role and must be taken into account.

D4-S5.7
Ni-Related Optical Centers in Diamond Produced by Ion Implantation. (#836) Julius Orwa, Steven Prawer; School of Physics, The University of Melbourne, Parkville, Victoria, Australia.

A viable approach in the current push towards quantum information processing (QIP) is based on integrated optical/solid state systems. Such systems require, as a basic resource, a stable single photon source. A suitable source for such photons is a stable two level system that can be addressed as an individual unit and that does not suffer from decoherence. Although there are many solid state systems that can support such a quantum mechanical system, the material of choice is diamond. Of the more than 100 optical centers in diamond, the nitrogen-vacancy center has been the most intensely investigated in the past few years because of its simplicity, brightness and relatively good photostability. Despite these excellent properties, production of reliable stable NV centers can be problematic, especially since the center occurs in two charge states, [NV]? (negatively charged) and [NV]0 (neutrally charged). Some spectral diffusion has been attributed to instability of the charge state of the NV defect. It has recently been demonstrated that Ni-related centers in diamond, in particular the NE8 center, can offer optical properties, including brightness and spectral line-widths that are superior to those of the NV. The structure of these centers is uncertain although some studies have shown that the NE8, which has a zero phonon line at ~800 nm, consists of one substitutional Ni surrounded by 4 N atoms. This study explores the creation of such centers in diamond in a controlled manner by implanting Ni and N atoms into ultra high purity single crystal type IIa diamond followed by thermal annealing. In particular we show that there are other Ni-related centers in diamond, besides the NE8, that can potentially be useful as photon sources for QIP. This study focuses on two Ni-related optical centers with zero phonon lines at ~711 nm and 883 nm. We show that the optical properties of these centers depend on implanted ion fluence and annealing temperature.

D4-S5.8
Planar X-Ray Waveguide-Resonator as the Base for Nanophotonic Instruments. (#343) Vladimir Egorov, Evgeniy Egorov; Institute of Microelectronics Technology and High-Purity Materials, Russian Academy of Sciences, IMT RAS, Chernogolovka, Moscow, Russian Federation.

The formation and fabrication of electromagnetic radiation fluxes with nanosize cross-section is the fundamental scientific research problem. Many science groups and institutes, had no draw own attention on financial and material expense often, are attended to search of this problem solution. At the same time, there is the simple and cheap technique for preparation of X-ray filiform fluxes with width 7-200 nanometers. This technique is founded on the planar X-ray waveguide-resonator (PXWR) which is used for the radiation flux formation and can be considered as the base for nanophotonic instruments [1]. PXWR is the device which is functioned in frame of the waveguide-resonance mechanism for X-ray quasi-monochromatic flux propagation. This mechanism differs from the multiple total reflection flux propagation which is the background for X-ray polycapillary optics, in principle. The multiple total reflection is characterized by a considerable intensity decreasing of X-ray flux. At the same time, the flux transported through the waveguide-resonance mechanism, undergoes very small attenuation. So, the mechanism got the second name - the radiation superstream mechanism. The theoretical consideration led grounds to expect and experimental investigations showed that the waveguide-resonance propagation mechanism for X-ray quasi-monochromatic flux can be realized in planar extended slit clearance with width smaller 200 nm. It turned out that the defining criterion for the mechanism realization is the alignment between the radiation coherence length (l2/Dl) and width of the transporting slit clearance. The mechanism manifests when the coherence length value will be greater than the clearance width. Features of the waveguide-resonator propagation mechanism for X-ray flux and device practical constructions based on PXWR design are discussed. [1] V.K. Egorov, E.V. Egorov. Planar air waveguide-resonator: a new device for X-ray optics // X-ray Spectrometry. v33. 2004. pp. 360-370.

D4-S5.9
Extraordinary Transmission of Nanohole Arrays in Gold Films. (#287) Alexander Minovich¹, Haroldo Hattori², Ian McKerracher², H. Hoe Tan², Dragomir N. Neshev¹, Chennupati Jagadish², Yuri S. Kivshar¹; ¹Nonlinear Physics Centre, Research School of Physical Sciences and Engineering, The Australian National University, Australian Capital Territory, Australia ; ²Electronic Materials Engineering, Research School of Physical Sciences and Engineering, The Australian National University, Australian Capital Territory, Australia.

We study experimentally the transmission of light through a square lattice of nanoholes perforated in a gold film. We observe that the structure periodicity enhances the light transmission for specific wavelengths, and we analyze this effect theoretically by employing the finite difference time domain (FDTD) calculations. Our samples are fabricated by focused ion beam milling of 200 nm thick film deposited on a quartz substrate. Various sample geometries were fabricated and tested. For experimental characterization of the spectral transmission through the films, we use a supercontinuum radiation delivered by a photonic crystal fiber. The generated supercontinuum spans over the wavelength range 450-1400 nm which allows for single shot transmission measurements over a broad spectral range. The supercontinuum beam is mildly focused onto the film to a focal spot of 20 μm, thus ensuring a plane phase distribution. The light transmitted through the film is then projected with a lens on a CCD camera and analyzed by a spectrometer. In our work, we focus on the measurements of the transmission spectra of two distinct arrays with a hole periodicity of 2 μm: Sample A consisting of 300 nm wide square holes and Sample B consisting of 800 nm wide holes. We find, that the sample with 800 nm hole size shows weak and broad transmission peaks near 800 nm wavelength range. These peaks appear complimentary to the broad transmission peak of pure gold around 550 nm. To understand the origin of these transmission peaks, we resort to numerical calculations of the transmission spectra. We utilize the FDTD algorithm and simulate short pulse transmission through the sample. In our simulations we use a non-uniform grid with size varying from 2 nm near the surface to 20 nm in a free space and a time step cT of 1 nm. For the Sample A (300 nm holes) the calculations did not reveal any plasmon resonances in the visible part of spectrum (apart from the pure gold transmission peak) but showed transmission peaks at infra-red wavelengths, at about 1.6, 2.3 and 3.2 μm. The Sample B (800 nm holes) on the other hand shows few weak peaks at around 900 nm, demonstrating similarities with the experimental data. A comparison of calculations of spectra for a nanohole arrays and for a single, isolated hole shows that the observed enhanced transmission peaks are clearly due to a collective effect from all the nanoholes. From our simulations, we are also able to obtain the actual field distribution of the excited surface plasmon modes at resonance frequencies. These mode distributions clearly show "hot spots" or local field enhancement, which can possibly allow for strong nonlinear effects or sensing applications. In addition, we study the optimization of the plasmonic structures for enhanced extraordinary transmission through the films, and also consider quasi-periodic and chirped arrays of nanoholes, which show promises for broadband extraordinary transmission.