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Volume 6989 Photonic Crystal Materials and Devices VIII

Richard M. De La Rue, Ceferino López, Michele Midrio, Pierre Viktorovitch April 2008

Conference Location: Strasbourg, France Conference Date: Tuesday 8 April 2008

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Front Matter

Select this Article OPEN ACCESS		Front Matter: Volume 6989 Proceedings of SPIE Proc. SPIE 6989, 698901 (2008); http://dx.doi.org/10.1117/12.801847 Online Publication Date: May 14, 2008 Full Text: \| Download PDF
	+ -	Show Abstract This PDF file contains the front matter associated with SPIE Proceedings Volume 6989, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

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3D Photonic Crystals and Volume 2D Photonic Crystals

Select this Article		Light transmission and scattering in engineered colloidal hetero-crystals Boyang Ding, Maria Bardosova, Ian Povey, Martyn E. Pemble, and Sergei G. Romanov Proc. SPIE 6989, 698903 (2008); http://dx.doi.org/10.1117/12.780876 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Heterogeneous 3-dimensional photonic crystals have been prepared by sandwiching self-assembled opal films and forced-assembled Langmuir-Blodgett colloidal crystal films. Strong transformation of the transmission spectra of the light traversing such hetero-crystals has been observed and interpreted in terms of the mismatch between eigenmodes of these photonic crystals and subsequent strong scattering at the interface between these crystals. Direct measurements of the spectra of forward scattered light have confirmed the peculiar character of the light scattering at the photonic crystal interface.

Select this Article		Novel method for fabrication of volume 2D photonic crystals Ryszard Buczynski, Ireneusz Kujawa, Adam Filipkowski, Dariusz Pysz, Florian Hudelist, Andrew Waddie, Ryszard Stepien, and Mo Taghizadeh Proc. SPIE 6989, 698904 (2008); http://dx.doi.org/10.1117/12.783611 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Photonic crystals are wavelength-scale periodic structures built from dielectrics with different refractive indexes As standard 2D photonic crystals are fabricated by lithographic methods, but in this case only planar structure can be obtained. We have adapted stack and draw technique that is usually used for photonic crystal fiber fabrication to develop volume 2D photonic crystals. Technology allows fabrication of high contrast structures with air holes as well as low contrast solid-all structures where air holes are replaced with glass micro rods of refractive index. Use of soft glasses with a high difference in refractive index allows development of a structure where partial photonic band gap exists. The proposed method offers possibility of fabrication volume 2D photonic crystal with a diameter in the order of 1 mm and height of a few mm. Large area photonic crystals are very attractive as new optical material named 'photonic glass' with built-in photonic bandgap functionality. Preliminary fabrication test were performed for two pairs of soft glasses NC21/F2 and SK222/Zr3. The considered glasses are thermally matched and are synthesized in-house except of F2 glass (standard Schott glass). Obtained structures are regular with some defects on the borders between intermediate performs. Some glass diffusion is observed between Zr3 and SK222 glasses. With this technique a 2D photonic crystal with a hexagonal lattice was fabricated with a pair of soft glasses SK222 and Zr3. Microrod diameter is 749nm and lattice constant 1110 nm. Photonic crystal consists of 166421 elements (425 elements on diagonal) and its total surface is about field ~0,178mm2.

Select this Article		Study of local dispersion in photonic crystal waveguide interfaces and hetero-structures Babak Dastmalchi, Reza Kheradmand, Mohammad R. A. Monazam, Abouzar Hamidipour, Abbas Mohtashami, Kurt Hingerl, and Javad Zarbakhsh Proc. SPIE 6989, 698905 (2008); http://dx.doi.org/10.1117/12.780871 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We have recently introduced a novel method to calculate local dispersion relation based on the Finite-Difference Time-domain and filter diagonalization method, which is suitable for local study of dispersion in optical waveguide, especially for the cases of non-periodic, curvilinear, and finite waveguides. In this paper, this approach is applied to study the photonic crystal waveguides at interfaces and double hetero-structure waveguides. We also studied the stretching effect, which is increasing the lateral distance between neighboring rods along guiding direction on band gap. Hybrid modes at interface are results of superposition of existing modes in adjacent waveguides. The results present a clear picture of localization mechanism of cavity modes and the transmission in the double-hetero-structures.

Select this Article		Two-dimensional and 3D multi-component photonic crystals: theory and experiment M. F. Limonov, A. V. Baryshev, A. B. Khanikaev, M. Inoue, M. V. Rybin, A. K. Samusev, K. B. Samusev, A. V. Sel’kin, and G. Yushin Proc. SPIE 6989, 698906 (2008); http://dx.doi.org/10.1117/12.780224 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We report on an analytical study of the photonic band structure of 2D and 3D multi-component photonic crystals. It is found that both types of crystal demonstrate a quasiperiodic resonant behavior of (hkl) photonic stop-bands as a function of the reciprocal lattice vector, providing a selective ON/OFF switching of nonresonant (hkl) stop-bands. Our predictions are compared with the results of conventional numerical studies using the photonic Korringa-Kohn-Rostocker method. Experimental transmission spectra of a-SiO2 synthetic opals show the OFF-switching of the {111} stop-bands at the filler permittivity of ~1.82, the {200} bands at ~1.63, the {220} bands at ~1.93, and the {311} bands at ~1.75. The (222) photonic stop-band, which is due to the second order diffraction from the (111) planes, cannot be switched OFF in a wide range of filler permittivity values, thus indicating a resonant behavior. The experimental data demonstrate an excellent agreement with the theoretical predictions.

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Quasi Photonic Crystals

Select this Article		Gap solitons in nonlinear spatiotemporal photonic crystals and gratings Fabio Biancalana, Andreas Amann, and Eoin P. O'Reilly Proc. SPIE 6989, 698909 (2008); http://dx.doi.org/10.1117/12.767235 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We have generalized the concept of nonlinear periodic structures to dielectric systems that show arbitrary spatial and temporal variations of the refractive index. Nonlinear pulse propagation through these spatiotemporal photonic crystals can be described, for shallow nonstationary gratings, by coupled mode equations which are a generalization of the traditional equations used for stationary Bragg gratings. Novel gap soliton solutions are found analytically. They represent a generalization of the gap solitons in static photonic crystals and resonance solitons found in dynamic gratings.

Select this Article		Periodically oscillating Anderson localization in random photonic superlattices with resonant units Mher Ghulinyan Proc. SPIE 6989, 69890A (2008); http://dx.doi.org/10.1117/12.779968 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract In strongly disordered systems, where Anderson localization is present, the mean transmittance (<T>) decays exponentially on average with increasing sample size. However, <T> often shows large fluctuations originating from extremely rare occurrences of necklaces of resonantly coupled states, possessing almost unity transmission. We show in this study that in one-dimensional (1D) random photonic systems with resonant layers these fluctuations appear to be very regular and have a period defined by the localization length ξ of the system. We demonstrate that necklace states are the origin of these well-defined oscillations. We predict that in such a random system efficient transmission channels form regularly each time the increasing sample length fits so-called optimal-order necklaces and demonstrate the phenomenon through numerical experiments. Our results provide new insight into the physics of Anderson localization in random systems with resonant units.

Select this Article		Light transport in planar dielectric optical waveguides based on the aperiodic Thue-Morse sequence Marianne Hiltunen, Jurgen Michel, and Luca Dal Negro Proc. SPIE 6989, 69890B (2008); http://dx.doi.org/10.1117/12.781073 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We present the design of a novel, CMOS compatible, waveguide structure capable of multifrequency transmission bands with strongly enhanced band-edge states. The concept of the structure is based on the aperiodic Thue-Morse fractal ordering of dielectric scattering subunits combined with a traditional channel-waveguide scheme. The design of the waveguide has been carefully optimized in order to ensure its manufacturability within standard CMOS processing. Due to the lack of translational symmetry, the proposed Thue-Morse waveguide is characterized by multiple photonic pseudoband-gaps and quasi-localized field states exhibiting large field enhancement effects.

Select this Article		Band gap characterization and slow light effects in periodic and quasiperiodic one dimensional photonic crystal J. Zaghdoudi, R. Kuszelewicz, M. Kanzari, and B. Rezig Proc. SPIE 6989, 69890D (2008); http://dx.doi.org/10.1117/12.780728 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Slow light offers many opportunities for photonic devices by increasing the effective interaction length of imposed refractive index changes. The slow wave effect in photonic crystals is based on their unique dispersive properties and thus entirely dielectric in nature. In this work we demonstrate an interesting opportunity to decrease drastically the group velocity of light in one-dimensional photonic crystals constructed form materials with large dielectric constant without dispersion). We use numerical analysis to study the photonic properties of periodic (Bragg mirror) and quasiperiodic one dimensional photonic crystals realized to engineer slow light effects. Various geometries of the photonic pattern have been characterized and their photonic band-gap structure analyzed. Indeed, one dimensional quasi periodic photonic multilayer structure based on Fibonacci, Thue-Morse, and Cantor sequences were studied. Quasiperiodic structures have a rich and highly fragmented reflectivity spectrum with many sharp resonant peaks that could be exploited in a microcavity system. A comparison of group velocity through periodic and quasiperiodic photonic crystals was discussed in the context of slow light propagation. The velocity control of pulses in materials is one of the promising applications of photonic crystals. The material systems used for the numerical analysis are TiO₂/SiO₂ and Te/SiO₂ which have a refractive index contrast of approximately 1.59 and 3.17 respectively. The proposed structures were modelled using the Transfer Matrix Method.

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Probing Photonic Crystals

Select this Article		Asymmetry reversal and waveguide modes in photonic crystal slabs E. F. C. Driessen, P. O. M. Heemskerk, D. Stolwijk, E. W. J. M. van der Drift, and M. J. A. de Dood Proc. SPIE 6989, 69890G (2008); http://dx.doi.org/10.1117/12.780455 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract The measured reflection spectra of two-dimensional photonic crystal slabs consist of an asymmetric peak on top of an oscillating background. For p-polarized light, the asymmetry of the peak flips for angles of incidence beyond Brewster's angle. We explain the observed line shapes with a Fano model that includes loss and use a waveguide model to predict the resonance frequencies of the photonic crystal slab. Finite-difference time domain calculations support the model and show that the resonance due to a higher order mode disappears when the substrate refractive index is increased beyond ns = 2.04. This is readily explained by the cut-off condition of the modes given by the waveguide model.

Select this Article		Optimization of a negative index photonic crystal slab at optical wavelength Nathalie Fabre, Xavier Mélique, Olivier Vanbésien, and Didier Lippens Proc. SPIE 6989, 69890I (2008); http://dx.doi.org/10.1117/12.780983 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract There has been an increasing interest in using photonic crystals as negative refraction index slabs for integrated nanophotonics. According to the superlensing criteria, a refractive index equal to -1 is needed to operate at an arbitrary wavelength [1-2]. The field distribution is the result of multiple propagation phenomena such as reflection, diffraction, self collimation and negative refraction. We report on the optimization of focusing properties of a triangular air hole lattice etched in a III-V semiconductor matrix and present the demonstration of negative refraction by FDTD 3D calculations. Under isotropy and finite length conditions, light transmission in the second band was investigated for an incident wave tilted by 0°, 2°, 7° and 15° (E Field parallel to the air holes). The advantage of our method lies in the existence of Fabry-Prot effect resulting of interferences between the front and the rear interface of the slab. From the comparison of each transmission spectrum, the filling factor was adjusted to obtain simultaneously n = -1 and a maximum of signal to operate at a wavelength of 1.55 micrometers. At least, the validity of this method to produce an intensity maximum behind the slab was checked by mapping the field with FDTD 3D simulations.

Select this Article		Arrays of selectively grown GaN micro-pyramids: photonic and optical-frequency phonon properties D. Coquillat, M. Le Vassor d'Yerville, P. Arcade, M. Kazan, C. Liu, I. M. Watson, P. R. Edwards, R. W. Martin, H. M. H. Chong, and R. M. De La Rue Proc. SPIE 6989, 69890J (2008); http://dx.doi.org/10.1117/12.785775 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract An array of GaN micro-pyramids containing a near-surface In_xGa_1-xN/GaN single quantum well has been fabricated using selective area epitaxial overgrowth above a patterned silica mask. The pyramid array has been studied by means of angle-resolved reflection measurements in the near- and mid- infrared optical ranges. We have found that the periodic array of flat-topped pyramids shows marked resonances in the near-infrared optical range due to resonant Bloch modes within the extraction cone and that the angular dispersion of these modes exhibits strong photonic crystal characteristics. The experimental results are in good agreement with the photonic band structure calculated using a scattering matrix formalism. The mid-infrared optical anisotropy properties of the micro-pyramids were investigated to probe the infrared active phonons of the pyramid array. The A₁(LO) phonon of the In_xGa_1-xN/GaN single quantum well was identified and the InN mole fraction was estimated from the mode behaviour.

Select this Article		Approaching quantitative optical diffraction analysis of crystal lattices in opal films W. Khunsin, C. M. Sotomayor Torres, and S. G. Romanov Proc. SPIE 6989, 69890K (2008); http://dx.doi.org/10.1117/12.780872 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Crystal ordering of opal-based self-assembled photonic crystals fabricated by vertical drawing deposition technique has been examined by the angle-resolved transmission spectroscopy. Assuming that minima in transmission spectra register the diffraction resonances occurring at different planes of the crystal lattice, the angle dispersions of these resonances reflect the ordering of the crystal lattice. Since such dispersions obtained as a function of the angle of light incidence cannot provide quantitative estimate of the crystal ordering without comparison to the adopted standard, we suggested to analyse the diffraction resonances as a function of the lattice rotation. This method allows to quantify the lattice ordering by the accuracy of the repetition of similar diffraction features upon the azimuth angle.

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Light Emission I

Select this Article		Analysis of the emission characteristics of photonic crystal LEDs Ch. Wiesmann, K. Bergenek, N. Linder, and U. T. Schwarz Proc. SPIE 6989, 69890L (2008); http://dx.doi.org/10.1117/12.780572 \| Cited 1 time Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Photonic crystals are known to enhance the extraction efficiency of LEDs and simultaneously shaping the emission pattern. In order to determine the radiation pattern we developed a model based on coupled mode theory that takes into account the lattice pattern, etch depth and the mode distribution. From a basic geometrical consideration a fundamental limit for the directionality is predicted. The calculations fit well to experimental data obtained from green InGaN LEDs incorporating a hexagonal PhC revealing a maximum directionality of 31% within 30°. Additional FDTD simulations were performed for determining quantitatively the extraction efficiency of PhC LEDs compared to LEDs with a roughened surface. Despite its lower overall extraction efficiency, the PhC LED outperforms a standard LED with surface roughening within an acceptance angle of 34° due to the higher directionality of the extracted light.

Select this Article		Control of mode volume and radiation dynamics of a slow-light-mode in a quasi-3D photonic crystal configuration Badhise Ben Bakir, Salim Boutami, Christian Seassal, Xavier Letartre, Jean-Louis Leclercq, Pierre Viktorovitch, Marc Zussy, Lea Di Cioccio, and Jean Marc Fedeli Proc. SPIE 6989, 69890M (2008); http://dx.doi.org/10.1117/12.781254 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We propose a new approach to realise surface addressable active photonic crystal devices. High Q-factor and low optical volume can be achieved combining lateral control of the mode size by a local modulation of the planar photonic crystal parameters, and vertical confinement assisted by a Bragg reflector. The low Q-factor of a 1D PC band edge mode can be increased up to 40000, while the optical mode volume is limited at the wavelength scale. Experimental results on laser operation achieved using this strategy in the case of an InP-based PC membrane bonded onto a Si/SiO2 Bragg reflector will be presented.

Select this Article		Tuning of spontaneous emission in photonic crystals by resonant energy transfer and magnetic fields W. Libaers, K. Baert, R. A. L. Vallée, B. Kolaric, and K. Clays Proc. SPIE 6989, 69890N (2008); http://dx.doi.org/10.1117/12.780261 Full Text: \| Download PDF
	+ -	Show Abstract The fluorescence of emitters embedded in a photonic crystal is known to be inhibited by the presence of a photonic pseudo-gap acting in their emission range. Here we present a comparative study of the influence of the pseudo-gap on the fluorescence emission of either organic dyes or nanocrystals embedded within a photonic crystal. Our results clearly show that the optical properties of the emitters are primarily controlled by the presence of a pseudo-gap which causes inhibition of the emission in both cases, regardless of the differences in chemical composition. These findings are mainly attributed to a decrease of the number of available photonic modes for radiative decay of the emitter in a photonic crystal compared to the effective homogeneous medium. Furthermore, we show that a photonic crystal can be used to control the fluorescence energy transfer (FRET) between donor-acceptor (D-A) pairs of dyes. Finally, we show that the application of an external magnetic field can finely tune the emission characteristics of emitters with a permanent magnetic moment.

Select this Article		1.5 μm photoluminescence of Er³⁺ in opal based photonic crystals G. Emelchenko, E. Steinman, V. Masalov, A. Tereshchenko, A. Bazhenov, and A. Grishin Proc. SPIE 6989, 69890P (2008); http://dx.doi.org/10.1117/12.778981 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract The study of the emission properties of opal-erbium oxide nanocomposites in the wide range of erbium concentrations was carried out. Erbium oxide concentration was varied from 0.25 to 16%wt. Maximal output of the photoluminescence (PL) took place at 1%wt of erbium oxide concentration. It was shown that the annealing temperatures from 600 to 900°C were too low to exhibit sufficient emission properties of the erbium-opal composites. The presence of the erbium silicates Er₂SiO₅ and Er₂Si₂O₇ in the opal-erbium nanocomposites was revealed by X-ray phase analysis. Amorphous silica in opal matrix was not crystallized at the annealing during a few hours at 1000 - 1200°C. The case of the tens hours of annealing the crystoballite phase occurred. No angle dependence of the PL intensity was observed as a result of degradation of the photonic band gap (PBG) at the annealing of the opal-erbium oxide nanocomposites. Further modification of the material processing to achieve a strong photonic band gap reflection peak near 1550 nm with high PL intensity in the opal-Er₂O₃ composite is running.

Select this Article		Photonic crystal laser based on activated glass Olga N. Kozina and Leonid A. Melnikov Proc. SPIE 6989, 69890Q (2008); http://dx.doi.org/10.1117/12.780853 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We present the results of calculations of the generation condition of laser with 1D and 2D PC structures. The spectral and spatial characteristics of finite length 1D and 2D PC with air-glass-doped layers was examined. For these calculations we used the transfer matrix formalism. The lazing optimum condition is determined.

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Light Emission II

Select this Article		Non-linear effects in luminescence of ZnO inverted opals W. Khunsin, P. Lovera, G. Redmond, C. M. Sotomayor Torres, M. Scharrer, L. Aagesen, R. P. H. Chang, and S. G. Romanov Proc. SPIE 6989, 69890R (2008); http://dx.doi.org/10.1117/12.780877 \| Cited 1 time Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Photoluminescence spectra of the ZnO carcass of inverted opal have been examined in the conditions of the strong lightto-structure interaction achieved by matching the photonic bandgaps of these photonic crystals to different parts of the ZnO emission spectrum. Developing the bands of enhanced spontaneous emission associated with both the emission of ZnO defects and the emission due to interband electron transitions has been observed. Interpretation has been given taking into account the coupling of emission to eigenmodes of 3-dimensional photonic crystal and the nature of the electron states involved in the radiative relaxation.

Select this Article		Control of pattern formation in a single feedback system by photonic bandgap structures N. Marsal, G. Montemezzani, M. Sciamanna, D. Wolfersberger, and D. N. Neshev Proc. SPIE 6989, 69890S (2008); http://dx.doi.org/10.1117/12.780969 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We present the observation of the manipulation of modulational instability in a nonlinear dissipative system by a periodic photonic lattice. We use a setup based on a photorefractive BaTiO₃ crystal in a single feedback mirror configuration leading to the formation of hexagonal patterns. Additionally, we impose an optical lattice to induce one or two-dimensional photonic band-gap structures with variable parameters. We show that by varying the lattice periodicity, thus adjusting the transverse spatial frequencies associated to the bandgap, we can induce patterns of particular symmetry or suppress the modulational instability when the position of the lattice bandgap coincides with the instability gain.

Select this Article		Thermal emission properties of 2D and 3D silicon photonic crystals Benjamin Gesemann, Stefan L. Schweizer, and Ralf B. Wehrspohn Proc. SPIE 6989, 69890T (2008); http://dx.doi.org/10.1117/12.781028 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We present measurements of the thermal emission properties of 2D and 3D silicon photonic crystals using either localized integrated emission sources or resistively heating the entire photonic crystals with and without substrate. The in-plane as well as out-of-plane emission properties were recorded and compared to numerical simulation.

Select this Article		Impact of dry-etching induced damage in InP-based photonic crystals Audrey Berrier, Yaocheng Shi, Jörg Siegert, Saulius Marcinkevicius, Sailing He, and Srinivasan Anand Proc. SPIE 6989, 69890U (2008); http://dx.doi.org/10.1117/12.781231 \| Cited 2 times Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this work variations of the carrier lifetime in a GaInAsP/InP quantum well in two-dimensional PhC structures etched by Ar/Cl₂ chemically assisted ion beam etching as a function of the processing parameters is investigated. It is shown that the deposition conditions of the SiO₂ mask material and its coverage as well as other process steps such as annealing affect the carrier lifetimes. However the impact of patterning the semiconductor on the carrier lifetime is dominant, showing over an order of magnitude reduction. For given PhC lattice parameters, the sidewall damage is shown to be directly related to the measured carrier lifetimes. A simple qualitative model based on sputtering theory and assuming a conical hole-shape development during etching is used to explain the experimental results.

Select this Article		Photonic crystal slab mirrors for an ultimate vertical and lateral confinement of light in vertical Fabry Perot cavities S. Boutami, B. Ben Bakir, X. Letartre, J. L. Leclercq, and P. Viktorovitch Proc. SPIE 6989, 69890V (2008); http://dx.doi.org/10.1117/12.781233 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Vertical Fabry Perot cavities (VFPCs) have enabled the realization of devices of great interest, like filters, photodetectors, VCSELs. In traditional VFPCs, the optical feedback is provided by two distributed Bragg Mirrors (DBRs). However, DBRs present two major drawbacks: they are generally rather thick mirrors, and they do not allow for a very high control on the lateral losses of the VFPC. We propose the use of a novel type of mirror, the photonic crystal slab mirror (PCM) which is able to overcome these limitations. In fact, we demonstrate that PCMs are ultra-thin single-layer mirrors that exhibit a very high reflectivity, and that allow also for a very tight control of the lateral velocity of photons, by a convenient engineering of the PCM Bloch modes. This concept will lead to the realization of ultra-compact and highly resonant VFPCs, interesting for VCSELs, non-linear optics-based devices, imaging, highly sensitive detectors, or 3D optical communication routing.

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Light Emission III

Select this Article		Vertical microcavities based on photonic crystal mirrors for III-V/Si integrated microlasers Lydie Ferrier, Salim Boutami, Fabien Mandorlo, Xavier Letartre, Pedro Rojo Romeo, Pierre Viktorovitch, Philippe Gilet, Badhise Ben Bakir, Philippe Grosse, Jean-Marc Fedeli, and Alexei Chelnokov Proc. SPIE 6989, 69890W (2008); http://dx.doi.org/10.1117/12.781328 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract The on-coming photonic layer of CMOS integrated circuits needs efficient light sources to treat and transmit the flow of data. We develop new configurations of III-V/Si vertical cavity lasers coupled to silicon optical waveguides using mirror/coupler based on photonic crystals. These devices can be fabricated using fully CMOS-compatible technological steps. Using this approach, the optical gain is provided by the III-V material, while all the remaining part of the optical cavity is in silicon. The output coupling to the sub-m waveguides of the CMOS optical layer can then be inherently optimised since the laser mirror/coupler and the Si output waveguides will be realised together during the same fabrication step. It has been demonstrated that photonic crystals membrane can act as very efficient reflectors (PCM-mirrors) for vertical microresonators. In this communication, the design of a vertical cavity microlaser based on these PCM-mirrors will be presented. We will show that high Q-factors (>10000) along with strong vertical and lateral confinements can be achieved. As a first demonstration, experimental results on silicon PhC-mirrors and associated vertical cavities will be discussed, showing Q factors larger than 2000. Finally, theoretical results on the coupling between such cavities and a silicon micro-waveguide will be presented.

Select this Article		A comparative study of directive emission from photonic quasicrystals Alessandro Micco, Vincenzo Galdi, Vincenzo Pierro, Alessandro Della Villa, Filippo Capolino, Stefan Enoch, and Gérard Tayeb Proc. SPIE 6989, 69890X (2008); http://dx.doi.org/10.1117/12.781686 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, we present a comparative study of the emission properties of line sources embedded in two-dimensional finite-size aperiodically-ordered "photonic-quasicrystal" slabs made of dielectric cylinders arranged according to representative categories of aperiodic tilings. Our study, based on a rigorous full-wave numerical method, indicates the possibility of achieving directive low-sidelobe emission at several frequencies. In this connection, parametric studies are presented, and similarities and differences with the periodic case are highlighted.

Select this Article		Static and dynamic properties of vertical-cavity surface-emitting semiconductor lasers with incorporated two-dimensional photonic crystals Pavel S. Ivanov, Yifei Zhu, Martin J. Cryan, Peter J. Heard, Ying-Lung D. Ho, and Judy M. Rorison Proc. SPIE 6989, 69890Y (2008); http://dx.doi.org/10.1117/12.783838 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract In oxide-confined Vertical-Cavity Surface-Emitting Lasers (VCSELs) the single-mode radiation is desirable for many applications. The single longitudinal mode is typical in VCSELs, however transverse optical modes can be controlled either with a small oxide aperture size [2] or small micropillar-like etched top distributed Bragg reflectors (DBRs) [3]. However, the power radiated from single-mode VCSELs is low and it results in low transmission distance in optical telecommunication networks. The power can be increased due to the fabrication of wider oxide aperture and wider top DBR, but than a VCSEL becomes multimode. Since the last decade photonic crystals had been introduced to control transverse optical modes of VCSELs [4-8]. The PC is created by periodic modulation of the refractive index in one, two or three space directions. In the VCSELs, the PC is positioned in top DBR and fabricated due to etching air-filled holes in the DBR. It was demonstrated that the PC reduces the transverse optical mode number, spectral linewidth [4-8] and increases the modulation bandwidth of VCSELs [9]. In this paper we present results of the investigated VCSELs with incorporated photonic crystals fabricated using the focused ion beam (FIB) machine. Power versus current, spectral and modulation characteristics of VCSELs with PC are investigated and compared to similar VCSELs with etched mesa.

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Metallic Photonic Crystals

Select this Article		Plasmonic excitations in ordered assemblies of metallic nanoshells N. Stefanou, C. Tserkezis, and G. Gantzounis Proc. SPIE 6989, 698910 (2008); http://dx.doi.org/10.1117/12.778589 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Periodic nanostructures for plasmonic engineering, comprising one or two types of silica core - metallic shell spherical particles, are studied by means of full electrodynamic calculations using the layer-multiple-scattering method. The complex photonic band structure of such three-dimensional crystals is analyzed in conjunction with relevant transmission spectra of corresponding finite slabs and the physical origin of the different optical modes is elucidated, providing a consistent interpretation of the underlying physics. In the case of binary structures, collective plasmonic modes originating from the two building components coexist, leading to broadband absorption and a rich structure of resonances and hybridization gaps over an extended frequency range.

Select this Article		Tunable Fabry-Perot THz filter with sub-wavelength grating mirrors Thorsten Goebel, Daniel Schoenherr, Cezary Sydlo, Axel Roggenbuck, Anselm Deninger, Peter Meissner, and Hans-Ludwig Hartnagel Proc. SPIE 6989, 698911 (2008); http://dx.doi.org/10.1117/12.781127 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We utilize the reflectivity of one-dimensional metal gratings with sub-wavelength slits to realize mirrors for THz frequencies. Two of them are combined to a Fabry-Perot filter, which features the corresponding transmission bands. By appropriate choice of dimensions, the extraordinary transmission resonance of the sub-wavelength gratings can be superimposed with the Fabry-Perot peak. By varying the resonator length between the grating mirrors, the overlap of both transmission peaks can be controlled. This enables the tuning of the filter bandwidth. The theoretical analysis shows that continuous tuning of the filter bandwidth up to 30% is possible for a two mirror stage. For the performance of comparative measurements, an all-fiber continuous-wave THz system is used. The experimental results are in fairly well agreement with the theoretically predicted tuning properties.

Select this Article		Coupled surface states in one- and two-dimensional frequency dependent photonic crystals Michael Bergmair and Kurt Hingerl Proc. SPIE 6989, 698912 (2008); http://dx.doi.org/10.1117/12.781260 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract One-dimensional photonic crystals with a frequency dependent material such as a metal or a polaritonic substance have very interesting properties. Their band structure can be calculated by a Kronig-Penney like equation where one uses next to the Bloch condition the continuity of the field and its derivative. The bulk absorption behaviour can be observed in the band structure as well but the size of the band gap is decreased proportional to the thickness of the frequency dependent layers. These absorption band gaps are complete for both polarisations and all angles of incidence except for modes propagating parallel to the surface. In this work these surface solutions are compared with ordinary surface plasmons and polaritons propagating on a simple metal/polaritonic to air interface. The band structure calculation of a two-dimensional frequency dependent photonic crystal is much more complicated. For a metallic photonic crystal flat bands occur in the band structure for a certain polarisation which are the surface plasmon (Mie) resonances. We show resulting the field enhancement by calculating the local density of states. Furthermore we investigate the band gap for the second polarisation and design a W1 wave-guide to demonstrate the localisation of the electromagnetic field.

Select this Article		Dynamic optical gratings in two layer system: ferroelectric and nanostructured metal film N. Kukhtarev, T. Kukhtareva, and G. Stargell Proc. SPIE 6989, 698913 (2008); http://dx.doi.org/10.1117/12.783025 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Dynamic reflection gratings, recorded by the single laser beam in ferroelectric crystals covered by nano-structured golden film generate optical and electrical pulsations. Frequency and amplitude of pulsations depend on laser intensity, the ambient pressure and temperature. Model explaining pulsations are developed based on the photogalvanic and pyroelectric mechanisms of holographic grating recording. Possible applications for the remote pressure and temperature sensing are discussed. Golden nanostructured film increase significantly sensitivity of the crystal pulsations to laser intensity, temperature and pressure. For a focused HeNe laser beam (intensity about 160mW/cm²) an interesting phenomenon (deserving special considerations) of self-phase conjugation was observed.

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NLO/Switching I

Select this Article		Second harmonic localization in nonlinear photonic crystals E. Centeno, C. Ciraci, D. Felbacq, and D. Cassagne Proc. SPIE 6989, 698915 (2008); http://dx.doi.org/10.1117/12.779700 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We demonstrate an isotropic phase matching condition achieved in nonlinear 2D PhCs that suppresses the incident angle constraint [1]. In addition, we show a backward SH localization effect by combining this unusual all-angle phase matching and left-handed PhC properties. The SH emission is confined in a small area of dimension close to the pump wavelength without the introduction of defect lattices. An analytical model is proposed in order to explain this parametric localization mechanism.

Select this Article		Nonlinear photonic structures for all-optical deflection Tal Ellenbogen, Ayelet Ganany-Padowicz, and Ady Arie Proc. SPIE 6989, 698916 (2008); http://dx.doi.org/10.1117/12.780808 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We demonstrate both experimentally and numerically continuous all-optical deflection achieved in specially designed photonic structures in quadratic nonlinear materials and discuss their special properties using Fourier space analysis. We designed and manufactured the proposed structures in a Stoichiometric Lithium Tantalate crystal. The inverted domains consist of a set of arcs arranged in the propagation direction. This arrangement results in a periodic pattern in the propagation direction and a chirped pattern in the transverse direction. A second harmonic generation experiment was performed on the crystal structures to examine the phase matching properties. Varying the pump wavelength from 1545 nm to 1536 nm at 150°C resulted in continuous angular deflection of the second harmonic wave up to ~2.5°. Continuous deflection was also obtained by varying the crystal temperature at a fixed pump wavelength. These structures can be used for various all-optical deflection applications, e.g. all-optical router using two cascaded nonlinear processes: an up-conversion process of signal and control beams, where the output channel is controlled by the frequency of the controlling beam, followed by a down conversion process, creating a beam at the signal frequency in the desired channel.

Select this Article		Quick and non-invasive method for characterisation of profiles of nano-photonics structures Szymon Lis, Rafal Dylewicz, Jarosław Myśliwiec, Andrzej Miniewicz, and Sergiusz Patela Proc. SPIE 6989, 698917 (2008); http://dx.doi.org/10.1117/12.785813 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Depth and profile information of one or two-dimensional photonic crystals can be obtained through measurements of reflective diffractive patters obtained from the structures and subsequent numerical analysis. The technique is known as a scatterometry. The method is non-invasive and fast, and competitive to the alternatives of AFM, SEM etc. In our paper we presented results of investigation 1D photonic crystal fabricated in GaN with period Λ = 400 nm, fill factor ff = 50% and depth d = 400 nm. Using computer algorithm of Rigorous Coupled Wave Analysis (RCWA) and measuring diffracted light we extracted the profile parameters of Λ = 420 nm, ff = 51%, d = 400 nm. Possibility of application of our method for analysis 2D photonic crystals is discussed also.

Select this Article		Few-cycle pulses interactions in nonlinear photonic crystals with managed dispersion Valery E. Lobanov and Anatoly P. Sukhorukov Proc. SPIE 6989, 698919 (2008); http://dx.doi.org/10.1117/12.781182 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Novel effects for few-cycle pulses propagation in quadratic media with dispersion management are considered. First, the process of extraordinary wave generation in uniaxial crystal is tightly related with the process of ordinary wave profile differentiation. Velocity mismatch limits interaction efficiency and leads to splitting of generated waves into two subpulses. Such effect can be suppressed in the medium with periodic modulation of quadratic nonlinearity or with velocity mismatch sign modulation. Second, highly interesting effects arise with the third-order dispersion. Dispersive spreading can be reduced in layered medium with alternating third-order dispersion coefficients. Quadratic photonic crystals with modulated dispersion coefficients or with managed dispersion are very promising for few-cycle pulse nonlinear optics. One- and two-wave soliton trapping and propagation dynamics are also studied in such crystals. The analytical theory is accompanied with the numerical simulation results.

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Fabrication/Devices I

Select this Article		High-transmission 1D photonic crystal/photonic wire multiple cavity structures based on silicon-on-insulator Ahmad Rifqi Md Zain, Nigel P. Johnson, and Richard M. De La Rue Proc. SPIE 6989, 69891A (2008); http://dx.doi.org/10.1117/12.780417 Online Publication Date: Apr 23, 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper describes the design, modeling, fabrication and characterization of single-row photonic crystal multiple micro-cavity structures embedded in 500 nm photonic wire waveguides. The strength of coupling between the resonators and the free spectral range (FSR) between the split resonance frequencies of the coupled-cavity combination were controlled via the use of different numbers of periodic hole structures - and through the use of different aperiodic hole taper arrangements between the two cavities in the middle mirror section of the mirrors. Both 2D and 3D finite-difference time-domain (FDTD) computations have been used to simulate the device structures. Comparisons have been made with the results of measurements and show good agreement.

Select this Article		Quality factor optimization of photonic crystal cavities through multiple multipole expansion technique and power loss integral Reihaneh Jannesary, Saeid Zamiri, Azar D. Mazaheri, Abouzar Hamidipour, Abbas Mohtashami, Kurt Hingerl, and Javad Zarbakhsh Proc. SPIE 6989, 69891B (2008); http://dx.doi.org/10.1117/12.781467 \| Cited 3 times Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Local Density of photonic States (LDOS) and Multiple Multipole Expansion technique (MME) are powerful tools in the study of spontaneous emission and calculation of photon confinement as well as efficient calculation of stationary field in planar photonic crystals. We bridge between optimization of Purcell factor and Q-factor in photonic crystal micro-cavities on one hand, and cavity power loss on the other hand. The quality factor calculated through a pulse response technique based on Finite Difference Time Domain (FDTD) simulations are compared with quality factor calculated by other approaches of LDOS and power loss. It turned out that the latter methods are more accurate and computationally less expensive. The cavity power loss is defined as the surface integration of energy density flow projected toward outside of the effective cavity volume. It is shown that size changes and shifting the neighboring rods or holes have a large impact on the mode volume and confinement. The quality factor optimization is performed for a H1- photonic crystal cavity, and mode volume investigations carried out for high Q factor arrangements. These investigations are resulted in effective structural design rules and geometrical freedom contour plots for the neighboring rods in the vicinity of the micro-cavity. These generalized design rules are suitable for further studies in other photonic micro-cavities.

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NLO/Switching II

Select this Article		Novel design of photonic crystal dense wavelength multiplexer based on nonlinear effect W. Aroua, F. AbdelMalek, S. Haxha, and H. Bouchriha Proc. SPIE 6989, 69891D (2008); http://dx.doi.org/10.1117/12.781397 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Using a two-dimensional Finite-difference time-domain method (2D FDTD), we present an extensive study of a new type of the wavelength multiplexer system. The self focusing and defocusing of the light beam are considered in this paper. The coupling between different kinds of components integrated in the same chip, in terms of coupling efficiency, is evaluated. Ultra-Dense Wavelength Division Multiplexing system (UDWDM) is of increasing demand since it provides large broad spectra that satisfy large number of users world-wide. This system can be used in the high-capacity optical fibre communication systems. The UDWDM plays a central role in optical interconnection required for high-dense integrated systems, in terms of light coupling between various optical chips.

Select this Article		All-optical diode action with Thue-Morse quasiperiodic photonic crystals Fabio Biancalana Proc. SPIE 6989, 69891F (2008); http://dx.doi.org/10.1117/12.767231 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We theoretically investigate the possibility of realizing a nonlinear all-optical diode by using the unique field-localization properties (known as Anderson-Kohmoto localization) of Thue-Morse quasiperiodic 1D photonic crystals. The interplay between the intrinsic spatial asymmetry in odd-order Thue-Morse lattices and Kerr nonlinearity gives rise to sharp resonances of perfect transmission that can be used to give a polarization-insensitive, nonreciprocal propagation with a contrast close to unity for low optical intensities. Such nonlinear diode would also represent the first all-optical device which is crucially based on Anderson-like localization.

Select this Article		Switching of electromagnetic eigenwaves in metastructures Eugene Y. Glushko Proc. SPIE 6989, 69891G (2008); http://dx.doi.org/10.1117/12.782789 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Switching effect based on controlled field redistribution inside the structure is analyzed for glass, silicon and Si/SiO₂ linear photonic crystals covered with Kerr nonlinear film. The spectrum and amplitude distribution for several types of 1D states: band, surface and pure local states are for Si/SiO₂ photonic structures are studied. The nonlinear shift of bandgap position in Si/SiO₂ linear photonic crystals covered with Kerr nonlinear film is investigated. Two schemes of all-optical signal processing are considered.

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Fabrication/Devices II

Select this Article		Efficient coupling of light between single-mode waveguides and supercollimating photonic crystals K. Vynck, E. Centeno, M. Le Vassor d'Yerville, and D. Cassagne Proc. SPIE 6989, 69891I (2008); http://dx.doi.org/10.1117/12.781135 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We study the coupling of light between strip and rib waveguides and supercollimating photonic crystals on silicon-on-insulator substrates. The dispersive properties of the supercollimating photonic crystal are used to define the design requirements on the excitation waveguide and the boundary of the photonic crystal is optimized to improve the impedance matching between the two structures. By 3D calculations, we find that rib waveguides can yield transmission effciencies up to about 96 % and reflections lower than 0.2 % at wavelengths close to 1.55 μm, while insuring single-mode propagation. This work therefore constitutes an important step toward the integration of supercollimation-based optical circuits on photonic chips.

Select this Article		Novel multiplexer/demultiplexer based on photonic crystal superprism W. Aroua, F. AbdelMalek, S. Haxha, and H. Bouchriha Proc. SPIE 6989, 69891J (2008); http://dx.doi.org/10.1117/12.781388 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We report a novel type of dispersive structure for wavelength multiplexer/demultiplxer based on a 2D photonic crystal (PC) prism. The novel device is proposed using super dispersion of a 2D PC. Simulation is carried out to determine the angular dispersion as a function of the period. The design has been optimized to improve the performance of a system with moderate refractive index contrast. It is shown that by varying the incident angle in a wavelength range from 1.3μm to 1.5μm, a superprism effect is observed. The performance of the devices is investigated in terms of sensitivity and resolution, which would help to understand the behaviour of the superprism prior to fabrication and its integration in photonic circuits.

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Fabrication/Devices III

Select this Article		Design criteria and 3D FEM modeling of air hole photonic crystal Alessandro Massaro, Vito Errico, Roberto Cingolani, Adriana Passaseo, and Massimo De Vittorio Proc. SPIE 6989, 69891O (2008); http://dx.doi.org/10.1117/12.781660 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract This work presents a detailed numerical Finite Element Method FEM modeling for passive optical components such as photonic crystals (PhCs). The accurate modeling characterizes the PhCs structures by considering the field resonance and the radiation behavior of the periodic pattern. The frequency responses at each side of the photonic crystal are evaluated by considering the 3D periodic structure enclosed in a black box with six input/output ports. This scattering matrix approach (SMA) is useful in order to evaluate in plane and vertical PhCs the resonance of the photonic crystal. Through the analysis of all the frequency responses we characterize the passband regions and the stopband regions of the PhC slab.

Select this Article		Temperature tuning of ultra-high Q/V SOI microcavities P. Velha, C. Jocteur, E. Picard, T. Charvolin, E. Hadji, J. C. Rodier, P. Lalanne, and D. Peyrade Proc. SPIE 6989, 69891P (2008); http://dx.doi.org/10.1117/12.781946 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Ultrahigh Q/V lineic silicon Fabry Perot (FP) microcavities relying on silica substrate have been fabricated. Two cavities designs are studied based respectively on cavity mode losses recycling and on mirrors with tapered sections. The experimental evolution of cavities characteristics are studied as a function of sample temperature. The authors achieve a quality factor of 58000 for a modal volume of 0.6 (λ/n)³.

Select this Article		Rod shape optimization in photonic crystal bends by the finite element method B. M. A. Rahman, Arti Agrawal, K. T. V. Grattan, and S. S. A. Obayya Proc. SPIE 6989, 69891Q (2008); http://dx.doi.org/10.1117/12.782348 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Modal solutions for Photonic Crystal with circular and square shaped rods have been obtained using the Finite Element method. We compare the field distributions and effective indices with rod shape in the Photonic Crystal. We optimize sharp 90° bends with different rod shape using a Finite Element Time Domain method.

Select this Article		Photonic crystal waveguide arrays Hamza Kurt Proc. SPIE 6989, 69891R (2008); http://dx.doi.org/10.1117/12.780961 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We carry out the study of two-dimensional photonic-crystal waveguide arrays (PCWA) composed of N waveguides coupled evanescently with each other. The coupling properties of the waveguide modes are investigated using coupledmode theory. One straightforward application of such an analysis is to channel input power from a central waveguide to side waveguides. As a result, the appropriate designs of PCWAs may permit the realization of efficient, compact and novel power dividers. For instance, we show that power dividers, switchers, and Mach-Zehnder interferometers can be feasible using N=3 channels. On the other hand, N=5 waveguides can split the input power by 1/4 at a certain length.

Select this Article		Photonic crystal-based WDM filter for integrated optical triplexer transceiver Dae-Seo Park, Jae-Hyun Kim, Beom-Hoan O, Se-Geun Park, El-Hang Lee, and Seung-Gol Lee Proc. SPIE 6989, 69891S (2008); http://dx.doi.org/10.1117/12.780779 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract We propose the new concept of an optical triplexer for an application of Gigabit Ethernet Passive Optical Network (GEPON) to Fiber-To-The-Home (FTTH) network. Based on a photonic crystal structure with local point defects, the optical triplexer is optimally designed. The proposed device is analyzed by the plane wave expansion method and its performance characteristics are evaluated by the finite-difference time-domain method. The optical triplexer proposed here is designed to have a compact size of about 4 × 3 μm² and the extinction ratios of -32.33 dB for 1310 nm, -19.84 dB for 1490 nm and -29.93 dB for 1550 nm, respectively.

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Poster Session

Select this Article		Complete photonic band gap in icosahedral quasicrystals with a body-centered six-dimensional lattice P. N. Dyachenko, V. E. Dmitrienko, Yu V. Miklyaev, and V. S. Pavelyev Proc. SPIE 6989, 69891T (2008); http://dx.doi.org/10.1117/12.780760 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract For the first time, the band structure of three-dimensional cubic photonic approximants of quasicrystals is studied theoretically. The approximants of different orders are found to have large, near-isotropic band gaps in a wide range of permittivity values. The effect of atom coordination on the size and threshold of the photonic band gap is explored. The existence of a complete band gap in the cubic photonic quasicrystal with a body-centered six-dimensional lattice is demonstrated.

Select this Article		Holographic fabrication of hierarchical nanostructures using microprism array toward optofluidic integration Seung-Kon Lee, Hyo Sung Park, Sung-Gyu Park, Jun Hyuk Moon, and Seung-Man Yang Proc. SPIE 6989, 69891U (2008); http://dx.doi.org/10.1117/12.784963 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract Holographic lithography provides a highly compatible and facile way to fabricate multi-dimensional periodic nanostructures. Periodic nanostructures have useful applications not only as biological substrates or catalytic supports but also as nanophotonic devices with various photonic properties such as photonic band-gap (PBG), localized surface plasmon resonance (LSPR) or surface enhanced Raman scattering (SERS). In combination with single refracting prism holographic lithography and conventional photolithography, we could achieve the micrometer-scale patterns of periodic nanostructures which can be integrated in microfluidic chip. With the help of conventional MEMS technologies, Arrays of pyramid shape and top-cut pyramid shape microprism can be prepared. Single laser exposure step through the microprism arrays (MPAs) can be generate multiscale patterns of 2D and 3D nanostructures. As prepared nanostructures combined with microfluidic chip is a highly efficient optofluidic platform which is applicable to the chemical and biosensors.

Select this Article		Dispersion and symmetry properties of anisotropic photonic crystals of arbitrary geometry and dimension Irina A. Khromova and Leonid A. Melnikov Proc. SPIE 6989, 69891V (2008); http://dx.doi.org/10.1117/12.780993 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract This work presents a fully vector plane wave method suitable for eigenwaves characteristics calculation for periodic dielectric media with arbitrary geometry and dimension, consisting of either isotropic or anisotropic materials. Using the method concerned, the influence of anisotropic material molecules reorientation in a photonic crystal on the symmetry properties of the dispersion surface of the latter. The work explains how the 2D anisotropic photonic crystal Brillouin zone shape depend on the anisotropic molecules orientation.

Select this Article		Periodic NLC phase grating for tuneable PBG applications R. Ghannam and A. Georgiou Proc. SPIE 6989, 69891X (2008); http://dx.doi.org/10.1117/12.780784 Online Publication Date: Apr 21, 2008 Full Text: \| Download PDF
	+ -	Show Abstract The advent of nanolithographic techniques has enabled electrically-driven liquid crystal devices to be addressed using nanoscale electrodes. Tiny periodic phase grating structures, which can now be realized, may find applications in optical communications and displays devices. Introducing optical discontinuities in the nematic liquid crystal (NLC) material will enable these structures to act as photonic band gap devices. This paper addresses the properties of band gap structures formed by NLC discontinuities using a 10micron thick homeotropically aligned NLC. It demonstrates how the position of the optical discontinuities may be altered by a symmetric voltage pattern and thus tune the photonic band gap.

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