This PDF file contains the front matter associated with SPIE Proceedings Volume 9127, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

We demonstrate a novel and very simple method allowing very easy flexible fabrication of 2D and 3D submicrometric structures. By using a photosensitive polymer (SU8) possessing an ultralow one-photon absorption (LOPA) coefficient at the excition laser wavelength (532 nm) and a high numerical aperture (NA = 1.3, oil immersion) objective lens, various submicrometric structures with feature size as small as 150 nm have been successfully fabricated. We have further investigated the energy accumulation effect in LOPA direct laser writing when the structure lattice constant approaches the diffraction limit. In this case, a proximity correction, i.e., a compensation of the doses between different voxels, was applied, allowing to create uniform and submicrometric structures with a lattice constant as small as 400 nm. As compared to commonly used two-photon absorption microscopy, the LOPA method allows to simplify the experimental setup and also to minimize the photo-damaging or bleaching effect. The idea of using LOPA also opens a new and inexpensive way to optically address 3D structures, namely 3D fluorescence imaging and 3D data storage.

Three-dimensionally (3D) ordered macroporous materials combine interesting structural and optical properties. Accessible and economic fabrication is essential to fully explore the unique possibilities these materials present. A common method to fabricate 3D ordered macroporous materials is by self-assembling colloids, resulting in so-called opals. A templating strategy is then often used to introduce additional functionality inside the porous structure, giving rise to inverse opals. In this work, we developed an easy and versatile method to fabricate highly uniform polymer inverse opals without overlayers. Briefly, our approach consists of sandwiching a resin melt between two opal templates, forcing all material inside or between the macroporous structures. The opal voids are fully filled and the superfluous melt material is extruded before curing the resin. Finally, the opal templates are removed by chemical etching. The resulting structures are freestanding 3D macroporous films with large-area uniformity, displaying strong photonic properties due to their structural order. Additionally, many applications require specific optical functionalities. The versatility of our templating method is uniquely suited for this purpose as it allows doping of the melt before infiltration. Therefore, we can incorporate a large variety of optical functions in the inverse opals using a single approach We believe this method will help the systematic investigation and improvement of existing effects in these structures, while providing a platform for the discovery and demonstration of novel effects. As this method combines 3D ordered macroporous materials with linear and nonlinear optical materials, it is even possible to tune optical interactions, which could be technologically relevant for OLEDs, solar cells, lasers, electro-optical modulators and optical switches.

We present designs for sharp bends in polymer waveguides using colloidal photonic crystal (PhC) structures. Both silica (SiO2) sphere based colloidal PhC and core-shell colloidal PhC structures having a titania (TiO2) core inside silica (SiO2) shells are simulated. The simulation results show that core-shell Face Centered Cubic (FCC) colloidal crystals have a sufficient refractive index contrast to open up a bandgap in the desired direction when integrated into polymer waveguides and can achieve reflection <70% for the appropriate plane. Different crystal planes of the FCC structure are investigated for their reflection and compared with the calculated bandstructure. Different techniques for fabrication of PhC on rectangular seed layers namely slow sedimentation; spin coating and modified doctor blading are discussed and investigated. FCC and Random FCC silica structures are characterized optically to show realisation of (001) FCC.

The properties of titania (TiO₂ ) are explored within the context of rolled-up nanotechnology, with particular attention to possible photonics applications. We show how the morphology of titania microtubes, as well as the TiO₂ phase and refractive index, can be controlled by properly tuning the microfabrication parameters. High refractive index TiO₂ tubes are proven to work as microresonators. The possibility of combining the rolling technique with an adequate prepatterning of the titania membrane could pave the way for the fabrication of a rolled-up diamond-like photonic crystal operating at visible frequencies, as substantiated by theory.

Since the first proposal of the idea of optical cloaking, huge research effort has been spent to implement hiding objects. We propose a broad band all-dielectric partial (unidirectional) cloaking device that hides arbitrary shaped objects. The cloaking structure is designed utilizing graded index (GRIN) photonic crystals. Refractive index distribution of the structure is chosen as a hyperbolic secant profile. In order to generate desired index profiles, both low and high dielectric backgrounds are chosen. The main principle of the cloaking in the study is separating the beam into two main parts while propagating through the composite device. Each part of the separated beam is strongly focused at the center of the stacked GRIN devices. Then these beams diverge and converge repeatedly without deteriorating the planar input field profile. This mechanism dramatically reduces the intensity at the center of the device. Therefore, existence of an object at the cloaked region almost does not affect wave front of the exiting beam due to this special light manipulation mechanism. In this manner, an observer cannot detect the hidden object. GRIN medium is a special type of inhomogeneous environment and light propagation is greatly affected by the presence of GRIN. Any partial cloaking solution as long as being practical and broadband in nature can be preferred. In this case, material selection and easy transferring the design to other electromagnetic spectrum regions become crucial. Therefore, the proposed idea in this work collects these desirable features.

We analyze laser-induced periodic structures developing in a semiconductor under both femtosecond pulse acting and external electric field action. These structures are appeared due to optical bistability appearance, which is caused by nonlinear dependence of semiconductor absorption coefficient from charged particles concentration. Dependence of the semiconductor absorption is induced as by the Fermi energy level renormalization so by the Burstein-Moss effect. The electron mobility, electron diffusion, and laser-induced electric field are taken into account for laser pulse propagation analyzing in semiconductor. We found out that an external electric field causes complicated motion of high absorption domain in a semiconductor. In certain cases, it causes drops developing of charged particles. External electric field acting can result in helical structures appearing of high concentration of generated charged particles. Moreover, under the action of the external electric field one can expect developing of chaotic spatio-temporal structure of charged particles which will induce chaotic changing of time-dependent optical radiation distribution. In turn, such spatio-temporal structures generate electro-magnetic waves with complicated pulse shape and spatial profile. It may be important at generation of the THz radiation because it changes the radiation generation direction.

Photonic systems with the capability to respond to different stimuli are more and more desirable for achieving multifunctionality and higher levels of performance. They demand materials with responsivity that may eventually be used for integrating sensing and actuating functions, a feature highly pursued in technological applications. A notable property which is being gradually incorporated in this kind of multifunctional materials is the shape memory effect (SME). In this work, a material system consisting of a two-dimensional photonic crystal (PC) imprinted in the surface of a shape memory polymer (SMP) is reported. It integrates several interesting features such as elasticity, thermoresponsivity and shape memory. The referred PC is composed of a hexagonal lattice of nanobowls, transferred to the SMP surface using replica molding. Good quality and large extensions of PC were achieved. Differential scanning calorimetry studies confirmed a melting transition responsible for the SME in these materials. From the structural point of view, their surfaces were characterized by atomic force and scanning electron microscopies. From the optical point of view, the characterization of the first order Bragg diffraction angle was carried out. A full programmable character of the structures, derived from the SME, was demonstrated. The reported material system presents some interesting additional features. In particular, the SMP selected for replicating the PC belongs to the family of polydiolcitrates, which are known to be biocompat- ible and biodegradable elastomers. The PC described herein is thus attractive for the development of disposable devices or for temporal usage in biomedicine or biophotonics.

We optimize a photonic crystal slab for the generation of second harmonic. The optimization consists in two steps. In the first step a regular photonic crystal, consisting in a triangular lattice of circular holes in a dielectric slab, is optimized by allowing for holes of three alternating radii, with the objective of obtaining a high-frequency bandgap doubly resonant with the fundamental one. The second step consists in modeling a L3 defect cavity in such a photonic crystal where, by further varying the radii and positions of a few neighboring holes, doubly resonant modes at the fundamental and second harmonic frequencies are obtained, with maximal Q-factors and field overlap. The structure emerging from this optimization procedure has Q-factors of 3400 for the fundamental mode and of 430 for the doubly resonant one. Due to the localized nature of those modes and hence their large field overlap, efficient second-harmonic generation is expected in a material with a X⁽²⁾ non-linearity.

The design, fabrication, and the experimental realization of high-Q slot photonic crystal cavities on SOI infiltrated by a liquid are reported. Loaded Q-factor of 23,000 is measured at telecom wavelengths. The intrinsic quality factor inferred from the transmission spectrum is higher than 200,000 whereas the maximum of intensity of the cavity is as high as 20% of the light transmitted in the waveguide in the bandpass wavelength range. This result makes the demonstrated filled slot photonic crystal cavities very promising for the integration of various active materials for light amplification, nonlinear optics, or sensing.

In open nanophotonic structures, the natural modes are so-called quasi-normal modes satisfying an outgoing wave boundary condition. We present a new scheme based on a modal expansion technique, a scattering matrix approach and Bloch modes of periodic structures for determining these quasi-normal modes. As opposed to spatial discretization methods like the finite-difference time-domain method and the finite element method, the present approach satisfies automatically the outgoing wave boundary condition in the propagation direction which represents a significant advantage of our new method. The scheme uses no external excitation and determines the quasi-normal modes as unity eigenvalues of the cavity roundtrip matrix. We demonstrate the method and the quasi-normal modes for two types of two-dimensional photonic crystal structures, and discuss the quasi-normal mode field distributions and Q-factors in relation to the transmission spectra of these structures.

We prepared thin film opal crystals and studied their angle-resolved transmission spectra in linear and circular polarized light as a function of the incidence angle and the azimuth rotation angle. We also explored the polarization conversion in linear and circular polarized light. Based on the spectra analysis we ascribed the polarization conversion in opal photonic crystal to properties of the Bloch modes of 3-dimensional photonic crystal.

Recently, we developed a new family of 3D photonic hollow resonators which theoretically allow tight confinement of light in a fluid (gaz or liquid): the photon cages. These new resonators could be ideal for sensing applications since they not only localize the electromagnetic energy in a small mode volume but also enforce maximal overlap between this localized field and the environment (i.e. a potential volume of nano-particles). In this work, we will present numerical and experimental studies of the interaction of a photon cage optical mode with nano-emitters. For this, PbS quantum dot emitters in a PDMS host matrix have been introduced in photon cages designed to have optimal confinement properties when containing a PDMS-based active medium. Photoluminescence measurements have been performed and the presence of quantum dot emitters in the photon cages has been demonstrated.

Ordered and disordered monolayers of spheres were assembled on dielectric and metallized substrate using the Langmuir-Blodgett style technique. The coexistence of Mie and diffraction resonances was investigated. Experiments showed the weak dependence of diffraction resonances on the distance between spheres, but their gradual destruction with increasing disorder. In turn, Mie resonances appear along the increased light localization in the monolayer, but experience strong blue shift and gradual reduction of the magnitude along the increased isolation in the lattice. Calculation proved that hybridization of Mie resonances rapidly vanishes along the increase of the spacing between spheres and the hopping of excitations between spheres can be expected only in tightly packed arrays.

Efficient photovoltaic conversion of solar energy requires optimization of both light absorption and carrier collection. This manuscript reviews theoretical studies of thin-film silicon solar cells with various kinds of ordered and disordered photonic structures. Light trapping capabilities of these systems are analyzed by means of rigorous coupled-wave analysis and compared with the so-called Lambertian limit as given by a fully randomizing light scatterer. The best photonic structures are found to require proper combinations of order and disorder, and can be fabricated starting from pre-patterned rough substrates. Carrier collection is studied by means of analytic models and by full electro-optical simulations. The results indicate that thin-film silicon solar cells can outperform bulk ones with comparable material quality, provided surface recombination is kept below a critical level, which is compatible with present-day surface passivation technologies.

Plasmonic nanostructures are known to influence the emission of near-by emitters. They can enhance the absorption and modify the external quantum efficiency of the coupled system. To evaluate the possibility of using plasmonics to enhance the light emission of a phosphor-converted LED device and create an efficient directional light source, regular arrays of aluminium nanoparticles covered with a red dye layer are investigated. In arrays of aluminum nanocylinders with a diameter of ca 140 nm combined with a thin (650 nm) layer of luminescent material, very narrow resonances have been observed, which lead to large enhancement factors of up to 70 and 20 for excitation with a directional blue laser source and a lambertian LED respectively, in a small spectral range for particular angles. The measured resonances agree very well with finite-difference time-domain numerical simulations. These changes in the angular emission profile of the red dye as well as the spectral shape of its emission can help to optimize the efficacy of phosphor-converted LED modules and increase the amount of useable light in a certain angular cone. Using Fourier microscopy, large modifications of the angular emission profile as well as spectral shaping are observed for these plasmonic LED devices if compared to reference samples without plasmonic nanostructures.

A tantalum tungsten (Ta-W) solid solution alloy, Ta 3% W, based 2D photonic crystal (PhC) was designed and fabricated for high-temperature energy conversion applications. Metallic PhCs are promising as high performance selective thermal emitters for solid-state thermal-to-electricity energy conversion concepts including thermophotovoltaic (TPV) energy conversion, as well as highly selective solar absorbers/emitters for solar thermal and solar TPV applications due to the ability to tune their spectral properties and achieve highly selective emission. The mechanical and thermal stability of the substrate was characterized as well as the optical properties of the fabricated PhC. The Ta 3% W alloy presents advantages compared to the non-alloys as it combines the better high-temperature thermo-mechanical properties of W with the more compliant material properties of Ta, allowing for a direct system integration path of the PhC as selective emitter/absorber into a spectrum of energy conversion systems. Furthermore, the thermo-mechanical properties can be fine-tuned by the W content. A 2D PhC was designed to have high spectral selectivity matched to the bandgap of a TPV cell using numerical simulations and fabricated using standard semiconductor processes. The emittance of the Ta 3% W PhC was obtained from near-normal reflectance measurements at room temperature before and after annealing at 1200°C for 24h in vacuum with a protective coating of 40nm HfO2, showing high selectivity in agreement with simulations. SEM images of the cross section of the PhC prepared by FIB confirm the structural stability of the PhC after anneal, i.e. the coating effectively prevented structural degradation due to surface diffusion.

Natural photonic structures found on the cuticle of insects are known to give rise to astonishing structural colours. These ordered porous structures are made of biopolymers, such as chitin, and some of them possess the property to change colour according to the surrounding atmosphere composition. This phenomenon is still not completely understood. We investigated the structure found on the cuticle of the male beetle Hoplia coerulea (Scarabaeidae). The structure, in this case, consists in a 1D periodic porous multilayer inside scales, reflecting incident light in the blue. The colour variations were quantified by reflectance spectral measurements using water, ethanol and acetone vapours. A 1D scattering matrix formalism was used for modelling light reflection on the photonic multilayer. The origin of the reported colour changes has to be tracked in variations of the effective refractive index and of the photonic structure dimensions. This remarkable phenomenon observed for a non-open but still porous multilayer could be very interesting for vapour sensing applications and smart glass windows.

In this paper, we propose a new technique for protein detection by using the enhancement of intensity in quantum dots (Qdot) whose emission is guided by 3D photonic crystal (PC) structures. For easy to use, we design the emitted light from the sensor can be recovered, when the chemical antibody (aptamer) conjugated with guard DNA (g-DNA) labeled with a quencher (Black FQ) hybridizes with the target proteins. In detail, we synthesis a Qdot-aptamer complex and then immobilize these complex on the PC surfaces. Next, we perform the hybridization of the Qdot-aptamer complex with g-DNA labeled with the quencher. It induces the quenching effect of fluoresce intensity in the Qdot-aptamer. In presence of target protein (thrombin), the Qdot-aptamer complex prefers to form the thrombin-aptamer complex: this results in the release of Black FQ-g-DNA and the quenched light intensity recovers into the original high intensity with Qdot. The intensity recovery varies quantitatively according to the level of the target protein concentration. This proposed sensor shows much higher detection sensitivity than the general fluorescent detection mechanism, which is functionalized on the flat surfaces because of the light guiding effect from 3D photonic crystal structures.

Guided mode resonance biosensors are of emerging interest as they allow integration on chip with fabrication on mass scale. The guided mode resonances (GMRs), observed in the transmission or reflection spectrum, are sensitive to refractive index changes in the vicinity of the photonic crystal (PhC) surface. Standard measurement setups utilize a collecting lens, focusing the extracted light intensity onto a single-point photo detector. In order to achieve highly miniaturized devices, we consider the integration of planar emitting and detector structures, such as organic light emitting diodes (OLEDs) and organic photo detectors (OPDs), together with the PhC based biosensors, on a single chip. This approach, however, consequently leads to a broadband, multi-angular light excitation as well as to a broadband and multi-angular contribution to the OPD photon count. While GMR effects in PhC slabs with directional light sources have been widely studied, this lens-less scenario requires a deep understanding regarding the broadband and the angular influence of both incident and reflected or transmitted light. We performed finite-difference time-domain (FDTD) calculations for GMR effects in two-dimensional (2D) PhC slabs. We study the effects for broadband emission in the visible spectrum, together with an angular incident beam divergence of up to 80°. We verified the simulated results by performing angle-resolved spectral measurements with a light emitting diode (LED) in a macroscopic, lens-less setup. We further utilize this numerical setup to provide a deeper understanding of the modal behaviour of our proposed OLED and OPD-based integrated biosensor concept.

We show that periodic distributions of gain or losses on the wavelength scale allow managing spatial diffraction of light beams, with no index contrast. It has been recently predicted that such artificial periodic structures, analogous to Photonic Crystals (PhCs), would also hold the novel spatial beam propagation effects reported for PhCs such as subdiffraction propagation, self-collimation, spatial filtering or beam focusing by a lens with flat interfaces. In particular, we consider an ideal periodic 2-dimensional (2D) arrangement of lossy cylinders embedded in air. We analytically show that this loss distribution affects diffraction. Indeed, a significant focusing behind a thin flat-flat crystal slab is observed, following the estimation of anomalous spatial dispersion for specific frequency ranges. Besides, close to the edges of the first Brillouin Zone, the light intensity map of a Gaussian beam exiting the lossy structure exhibits a high transmission windows instead of the transmission stop band expected for PhCs. This results from the strong anisotropic attenuation provided by the loss periodicity. Finally, we also consider a more realistic system with combined modulations of refractive index and losses: a 2D metallic photonic crystal (MPhC). We demonstrate that MPhCs also support selfcollimation and focusing, being such effects associated to zero and negative diffraction respectively. Finally, due to the anisotropic attenuation of light, the structure is also able to spatially filter noisy beams.

We reveal new and remarkable manifestations of the Fano resonances in high-refractive-index all-dielectric photonic nanostructures. First, we revisit the conventional problem of light scattering by an infinite dielectric rod and observe the existence of cascades of Fano resonances in the optical cross-section, which we investigate both numerically and analytically. Our analytical study is based on the exact Mie solution of Maxwell’s equations for the light scattering by spatially homogeneous bodies of revolution. Next, we study the photonic bandgap structure and transmission spectra of two-dimensional square lattices of dielectric circular rods. We vary the refractive index of the rods from low to high values and observe a remarkable manifestation of a novel type of Fano resonances arising due to interplay between the resonant Mie scattering from individual rods and the Bragg scattering from the photonic lattice.

Slow light in SOI Slotted Photonic Crystal Waveguides (SPCW) infiltrated by a refractive liquid are investigated. By employing an interferometric technique similar to Optical Coherent Tomography (OCT), we report a group velocity lower than c/20 over a 1 mm-long SPCW. From the OCT measurements, we also infer moderate propagation losses. In the fast light regime (n_G <10) propagation loss is about 15 dB.cm^-1. Moreover, the coupling to slow modes is efficient. These results show that infiltrated slow light SPCW are a promising route to silicon organic hybrid photonics.

Nanobeam cavity waveguides have drawn great attention of the researchers due to being a useful optical platform for several applications, e. g. optical switching and filtering.1 Almost all of the past studies investigated high quality (Q) factors without considering polarization independency. In the literature Zhang et al. proposed a device that enables high Q for both transverse electric (TE) and transverse magnetic (TM) modes for a specific frequency.2 In our study we demonstrate a three-dimensional study of polarization independent nanobeam cavity waveguide that consists of annular photonic crystals (PCs) showing similar optical properties for both TE and TM modes.3 Besides, a detailed analysis of the shift of the overlapped frequency is investigated with respect to height and width variation of the nanobeam structure. The designed waveguide is composed of 12 air holes and 4 annular PCs located in the Silicon (nSi=3.46). The radii of all air holes in the structure are 0.36a. The annular PCs at the interior section have inner dielectric radii of 0.18a and the outer ones have inner dielectric radii of 0.20a. Silica (nSilica=1.52) material is used as a substrate. The width and height of the waveguide may be tuned in order to obtain high Q factors at the desired frequency for both polarizations. In our analysis, we investigated the relation between widths, height and cavity frequency for both TE and TM cases. Obtained frequencies are fitted to cubic polynomials of the structural parameters width and height. Overlapped frequency curve is revealed by an equalization of the polynomials of TE and TM resonant frequencies. The findings elucidate the effect of the parameters on the overlap mechanism of resonant mode matching for both polarizations.

Strict process control, combined with proprietary process enhancements have enabled the production of large-scale single-crystal sapphire that demonstrates crystalline quality in excess of what has previously been possible. Extremely low defect densities, narrow rocking-curves, and very low stress gradients in the material are demonstrated through various X-ray diffraction techniques.

New procedure of designing slotted photonic crystal waveguides (SPCW) is proposed to achieve slow light with improved normalized delay-bandwidth product (NDBP) and low group velocity dispersion, which is suitable for both the W1 defect mode and the slot mode. The lateral symmetry of the waveguide in our study is broken by shifting the air holes periodically along the slot axis . The conversion of the “flat band” from band-up slow light to band-down slow light is achieved for W1 defect mode. The group index curves of W1 mode change from U-like to step-like and the group index of 47, 67 and 130 are obtained with the bandwidth over 7.2, 4.8, and 2.3nm around 1550nm, respectively. We also obtain the group index of 42, 55, and 108 for the slot mode with the bandwidth over 6.2, 5.6, and 2.2nm. Then the low dispersion slow light propagation is numerically demonstrated by the finite-difference time-domain method.

It has been studied the spectral characteristics of the porous silicon dioxide and cholesteric liquid crystal. It has been shown that doping of the EE1 cholesteric liquid crystal with Fe3O4 magnetite nanoparticles doesn’t shift significantly the position of the transmittance minimum of the material. It has been found that the deformation of chiral pitch of cholesteric liquid crystal with magnetite is observed in case of doping of porous nanocomposite host with following shifting of minimum of transmittance into short wavelength direction. It has been shown that influence of carbon monoxide on optical characteristics of the cholesteric liquid crystal with magnetite can be explained by the interaction of CARBON MONOXIDE molecules with magnetite nanodopants.