Light propagation in a low index core (e.g. SiO2) is realized by a Photonic Band Gap (PBG) cladding waveguide structure with large dielectric index contrast layers (Si/Si3N4). The waveguide is fabricated with a CMOS compatible process. The measured loss for the asymmetric PBG cladding waveguide is about 0.5dB/cm for both polarizations at a wavelength of 1550nm. Potential applications include optical amplification when the SiO2 core is doped with optical active materials (e.g. Er).

We propose the design of a new taper to improve light coupling between a photonic-crystal-based W1 waveguide and a ridge waveguide of similar width. The taper design is directly deduced from band structure calculations and allows an adiabatic mode conversion. The comparison between light propagation from the ridge waveguide through the W1 waveguide and through the taper, respectively, shows good improvement of the coupling efficiency.

Thin films composed of MgF2 and TiO2 were grown by glancing flux incidence, where the physical vapor flux arrives at the substrate between 80° and 90° with respect to substrate normal. The resulting films are composed of slanted columns inclined toward the incoming flux. The films were modeled using the Bruggemann effective medium approximation (EMA) and were found to be biaxial with one of the principal indices of refraction along the direction of the posts. The indices of refraction for MgF2 and TiO2 films were found to be in the range of 1.06 to 1.2 and 1.36 to 1.62, respectively, at a wavelength of 600 nm. The indices of refraction were found to decrease as the deposition angle increased. The film density was also found to be independent of the film thickness for films ranging in thickness from 500 nm to 3400 nm.

Photonic crystals are periodic dielectric structures that have a photonic band gap to control the propagation of light in a certain wavelength range. This property offers a means to manipulate photons in the same way as electrons can be controlled in an atomic lattice. Porous silicon is an ideal candidate fo r the fabrication of photonic crystals because of the availability of a variety of silicon micromachining techniques. One-dimensional photonic crystals with customized parameters can be economically fabricated using porous silicon multilayer structures with periodically modulated porosity. Despite the structural non-homogeneities, porous silicon fabricated on a p-type Si substrate has optical properties similar to a dielectric material with a single effective refractive index. The exact value of the refractive index for each layer depends on its porosity. An engineered porosity can be obtained by changing the etching currents during the anodization process. This results in a modulation of the refractive index. A stack of alternating layers with high and low porosity produces a distributed Bragg reflector (DBR). Various designs incorporating multilayer porous silicon structures with an optical Fabry-Perot resonator and coupled microcavities are under development and can serve as an optical filter. Prototypes of such free-standing structures with 21–200 stacked layers to be used as DBRs, Fabry-Perot resonators or coupled microcavities are being fabricated. These structures are coated with polystyrenesulfonate on their backsides to increase mechanical strength and at the same time maintain flexibility. In this work, reflectance spectra of these porous silicon multilayers with and without polymer on the backside were measured. Simulations of the multilayer one-dimensional photonic crystals were performed to predic t the reflectance spectrum and optimize their structures before the fabrication and to compare to experimental data.

We have developed a nano-micro structure fabrication method in rutile TiO2 single crystal by use of swift heavy-ion irradiation. The area where ions heavier than Cl ion accelerated with MeV-order high energy were irradiated was well etched by hydrofluoric acid, by comparison etching was not observed in the pristine TiO2 single crystal. Noticed that the irradiated area could be etched to a depth at which the electronic stopping power of the ion decayed to a value of 6.2keV/nm. We also found that the value of the electronic stopping power was increased, eventually decreased against depth in TiO2 single crystal with, e.g. 84.5MeV Ca ion. Using such a beam, inside of TiO2 single crystal was selectively etched with 20% hydrofluoric acid, while the top surface of TiO2 single crystal subjected to irradiation was not etched. Roughness of the new surface created in the single crystal was within 7nm with the atomic forth microscopy measurement.

We model the operation of a micro-optical interferometer for surface plasmon polaritons (SPPs) that comprises an SPP beam-splitter formed by equivalent scatterers lined up and equally spaced. The numerical calculations are carried out by using a vector dipolar model for multiple SPP scattering. The SPP beam-splitter is simulated for different angles of the incident SPP beam, radii of the particles, and inter-particle distances in order to find a suitable configuration for realization of a 3dB SPP beam-splitter. The results obtained are in good agreement with experimental data available in the literature. The feasibility of fabricating an interferometer is thereby corroborated and the calculated intensity maps are found rather similar to those experimentally reported.

We present a study of various photonic crystal taper structures each characterized by the taper angle and roughness for coupling light into 2-dimensional photonic crystal waveguides from large ridge waveguides. The photonic crystal waveguide is made of a triangular lattice of holes in a dielectric. The objective is to find a taper structure that offers the best coupling efficiency over a range of widths of the ridge waveguide while leaving a small footprint. We show that such a structure indeed exists and can be further optimized as the width of the ridge waveguide gets even larger leading to more than 90% increase in coupling efficiency in some cases.

Porous silicon is an efficient photo- and electro-luminescence material and represents a promising candidate for opto-electronic applications. In the last years, porous silicon multilayers with a high enough refractive index contrast have been obtained. In this work, we study the light transmission in Fibonacci multilayers made of porous silicon. The theoretical reflectance spectra are compared with experimental data, observing a good agreement, even though they are extremely fragile when the number of quasiperiodic layers increases. The photoluminescence spectra show evidences of the quasiperiodic structure and in particular, the observed enhancement in comparison with that of single porous silicon layer could be due to the quasiperiodicity.

We have recently reported the fabrication of Si based subnanometer linewidth microcavities and omnidirectionnal mirrors. The structures were made of microporous silicon by electrochemical anodization. The structure high quality and the observation of omnidirectionnal stop bands have been made possible by the optimisation of the starting material, the etching conditions, and the structure design. In this paper we discuss more specifically the choice of these parameters considering the material intrinsic limitations.

We report on the growth of GaAs and GaAs/AlGaAs heterostructured hexagonal pillar arrays using selective area (SA) metalorganic vapor phase epitaxy (MOVPE) for the application of two-dimensional photonic crystals (2D-PhCs). SA-MOVPE was carried out on SiO2 masked (111)B GaAs substrates with circular or hexagonal hole openings. Extremely uniform array of hexagonal GaAs/AlGaAs pillars consisting {110} vertical facets with their diameter of order of 200 nm were obtained. Unexpectingly strong intense light emission was observed for the room temperature photoluminescence measurement, which suggests low surface nonradiative recombination and enhancement of the light extraction efficiency of the pillar arrays.

Recent progress on photonic crystal fibers (PCFs) is reviewed aiming at their application to high performance optical communications sytems. The optical properties, for example dispersion characteristics, can be set by selecting the appropriate combination of air hole diameter and air hole pitch. A noteworthy characteristic of PCFs is their strong birefringence, which suggests optical components with better polarization maintaining characteristics.

This paper describes the characteristics of dispersion controlled PCFs and polarization maintaining PCFs. It describes theoretical analyses and experimental results of fabricated PCFs that have short wavelength zero dispersion at 810 nm, polarization maintaining capability with birefringence of 1 × 10−3, polarization maintaining dispersion flattened functions, and absolute single polarization state support with polarization dependent loss of 1 dB/m at 1550 nm. A supercontinuum generation experiment with PM-PCF in the 1550 nm region is shown with symmetrical spectral broadening to over 40 nm. The potential of PCFs will be discussed with reference to the next generation optical communications systems.

Photonic microcavity promises to be one of the photonic devices that can have immediate applications such as super bright LED and low threshold laser. Most photonic crystal structures currently used on microcavity are cubic or hexagonal, whose folding symmetry is no greater than 6. In this work, we fabricated 2-D photonic microcavity with Penrose quasicrystal pattern and measured the angular resolved transmission and photoluminescence spectra of the microcacity. From the experimental result it is found that isotropic photonic band gap exists in the microcavity with the Penrose quasicrystal pattern.

We propose a novel high-index-contrast waveguide structure capable of light strong confinement and guiding in low-refractive-index materials. The principle of operation of this structure relies on the electric field (E-field) discontinuity at the interface between high-index-contrast materials. We show that by using such a structure the E-field can be strongly confined in a 50-nm-wide low-index region with normalized average intensity of 20 μm−2. This intensity is approximately 20 times higher than that can be achieved in SiO2 with conventional rectangular or photonic crystal waveguides.

A new method is presented, based on the discrete Fourier Transform, for the design of aperiodic lattices to be used in photonic bandgap engineering. Designing an aperiodic lattice by randomly choosing defects is unlikely to result in useful optical transmission characteristics. By contrast, this new method allows an aperiodic lattice to be designed directly from the desired optical characteristic. The use of this method is illustrated with a design for a structure to realise two transmission wavelengths in the stopband of a one-dimensional photonic lattice. This design has been fabricated in silicon-on-insulator and some optical characteristics are given.

We consider the long-wavelength limit for two-dimensional photonic crystals - periodic arrangement of magneto-dielectric rods with dielectric and magnetic constant εa and μa embedded in a magneto-dielectric background (εb,βb). Using the Fourier expansion method in the low-frequency limit (ω → 0 ) we develop an effective medium theory and give a rigorous proof that, in this limit, a periodic medium behaves like a homogeneous one. We derive compact analytical formulas for the effective index of refraction of a 2D photonic crystal. These formulas are very general, namely the Bravais lattice, the cross-sectional form of cylinders, their filling fractions and the dielectric and magnetic constants are all arbitrary. For non-magnetic materials, μa = μb = 1, we show how to introduce index ellipsoid and demonstrate that the E-mode is an ordinary wave and the H -mode is an extraordinary wave. For magnetic materials the both modes turn out to be extraordinary. This unusual property is unknown for natural crystals.

We present and characterize hexagonal point defects in a two dimensional photonic crystal based on macroporous silicon. These point defects are prepatterned periodically, forming a superstructure within the photonic crystal after electrochemical etching. Spatially resolved, optical investigations related to morphological properties, like defect concentration and pore radius, are compared to bandstructure calculations. The confined defect states are identified and their interaction is evaluated quantitatively.

A method for measuring locally the normalised reflectivity spectrum in waveguiding photonic structures is presented. The latter is obtained by imaging the standing wave pattern upstream of the structure with a scattering type Scanning Near-field Optical Scanning Microscope (s-SNOM) and normalised with a simple Fourier analysis. Two kinds of sample are investigated. The first one is a corrugated integrated waveguide, the second is a fiber Bragg grating. The s-SNOM technique applied to waveguiding structures is first introduced with the case of a straight waveguide.

Anisotropic nanostructuring of bulk silicon (Si) leads to a significant optical anisotropy of single porous silicon (PSi) layers. A variation of the etching current in time allows a controlled modification of the porosity along the growth direction and therefore a three-dimensional variation of the refractive index (in plane an in depth). This technique can be important for photonic applications since it is the basis of a development of a variety of novel, polarization sensitive, silicon-based optical devices: retarders, dichroic Bragg Reflectors, dichroic microcavities and Si based polarizers.