Porous layers and membranes representing 2D and 3D dielectric structures were fabricated on different III-V compounds (GaAs, InP, GaP) by electrochemical etching techniques. Nonlithographically fabricated ordered nanopore arrays in InP are reported for the first time. We show that the reflectance from nanostructured InP is lower than that from bulk InP in the spectral interval 1.5-2.2 eV. The artificial anisotropy induced by nanotexturization was studied in porous GaP membranes and the refractive indices for ordinary and extraordinary beams were evaluated.

As demonstrated for the example of a diamond and zinc blende structure of dielectric spheres, small inclusions of a low absorbing metal with the volume fraction fm can have a dramatic effect on a complete photonic band gap (CPBG) between the 2nd-3rd bands. For example, in the case of silica coated silver spheres, the CPBG opens for fm ≍ 1.1% and exceeds 5% for fm ≍ 2.5%. Consequently, any dielectric material can be used to fabricate a photonic crystal with a sizeable and robust CPBG in three dimensions. Absorption in the CPBG of 5% remains very small (≤ 2.6% for λ ≥ 750 nm). The structure enjoys almost perfect scaling, enabling one to scale the CPBG from microwaves down to ultraviolet wavelengths.

We present a photonic crystal narrow pass-band optical filter, which is made of two pieces of photonic crystals with different photonic band gaps. Our numerical investigations show that this kind of structure is feasible for narrow pass-band optical filtering. The pass-band may be less than 0.1nm in the infrared communication frequency band. In ideal cases, the optical transmission in the pass band is very close to 1. This means a very low insert energy loss.

The transfer matrix method (TMM) software (Translight, A. Reynolds [1]) was used to evaluate the photonic band gap (PBG) properties of the periodic arrangement of high permittivity ferroelectric composite (40 wt% Ba0.45Sr0.55TiO3 /60 wt% MgO composite, εR= 80, tanδ = 0.0041 at 10 GHz) in air (or Styrofoam, εR~ 1) matrix compared to a lower permittivity material (Al2O3, εR= 11.54, tanδ = 0.00003 at 10 GHz) in air. The periodic structures investigated included a one-dimensional (1D) stack and a three-dimensional (3D) face centered cubic (FCC) opal structure. The transmission spectrum was calculated for the normalized frequency for all incident angles for each structure. The results show that the bandgaps frequency increased and the bandgap width increased with increased permittivity. The effects of orientation of defects in the opal crystal were investigated. It was found by introducing defects propagation bands were introduced. It was concluded that a full PBG is possible with the high permittivity material.

We present three-dimensional analysis of two-dimensional guided resonances in photonic crystalslab structures. This analysis leads to a new understanding of the complex spectral properties of such systems. Specifically, we calculate the dispersion diagrams, the modal patterns, and transmission and reflection spectra of these resonances. From these calculations, a key observation emerges involving the presence of two temporal pathways for transmission and eflection processes. Using this insight, we introduce a general physical model that explains the essential features of complex spectral properties. Finally, we show that the quality factors of these resonances are strongly influenced by the symmetry of the modes, and the strength ofthe index modulation.

A double-layer photonic crystal (PhC) possessing incomplete photonic band gap (PBG) has been prepared by successive formation of one opaline film on top of another and subsequent impregnation with CdTe colloidal nanocrystals as the light source. Transmission, reflection and photoluminescence (PL) spectra of this nanocomposite have been measured from 1.8 to 2.5 eV at different angles of the light incidence and detection. The suppression of emission intensity has been found at both stop bands of the PhC heterostructure. Depending on the excitation power, either suppression or enhancement of the emission rate at the stop band has been observed.

We describe a technique for obtaining effective second order non-linearity λ2in non centro-symmetric Photonic Crystal made from centro-symmetric materials (e.g. glass, Ge or Si). The effect is based on the electric quadrupole transition, strong electromagnetic mode deformation and different contributions to the volume polarization from different parts of the photonic crystal1.

The phase characteristics of transmitted optical pulses in three-dimensional photonic crystals were investigated in the frequency and time domain by using the spectrally resolved cross-correlation technique. The temporal evolution of femtosecond pulses passing through polystyrene colloidal crystals exhibits a large phase distortion near the stop bands. The phase discontinuity around the band gap was observed in the frequency-domain. The phase of the transmitted pulses is found to change by π across the band gap. The dispersion curve estimated from the phase shift shows good correspondence with those calculated from a photonic band calculation. The group velocity significantly slows down near the stop bands. A large change of the group velocity dispersion is also observed near the band edges. These results are in good agreement with the band theory.

We propose a new three-dimensional photonic crystal structure or drilled alternating-layer photonic crystal (DALPC), which can be fabricated by a combination of the deposition of alternating layers of dielectric films and one-time dry etching. Our band calculation predicts that the DALPC has a photonic band gap (PBG) in all directions. We fabricated a Si/SiO2 DALPC by electron beam lithography, bias sputtering, and fluoride-gas electron cyclotron resonance etching. We measured the light transmission of the DALPC sample in both the in-plane and vertical directions. We observed a transmission minimum around the 1.4-µm-wavelength for all measured directions and TE/TM polarizations, which demonstrated a potential of the DALPC as a three-dimensional PBG material.

We introduce and explore two- and three-dimensional lattices formed in Holographic-Polymer Dispersed Liquid Crystals (H-PDLC) materials, which exhibit an electrically controllable index modulation in multiple dimensions. As electro-optically active holograms, these materials exhibit fast dynamic switching phenomena (~100 microseconds), and are simple to fabricate. While many applications have been proposed for these materials, almost all are based on one-dimensional index modulations in various grating regimes. However, constraints in additional dimensions lead to a much greater sensitivity of the polymer morphology to monomer functionality, exposure irradiance, and grating pitch. In an effort to begin to understand this relationship, two-dimensional triangle lattices were created using two monomeric blends exposed over a range of powers. Final diffraction efficiency (Bragg regime), saturation voltage, and polymer morphology were examined from the resulting triangle lattices. Three- dimensional lattices are discussed and a six-beam holographic method is proposed. Photonic crystal applications are envisioned where the pseudo-bandgap can be electrically controlled.

A new method for the patterning of colloidal particles on polymer templates is presented. A polyelectrolyte multilayer film is deposited onto a chemically patterned monolayer surface, which is further used as a functional template to direct the deposition of charged particles through electrostatic and secondary interactions. After modified by an opposite charged surfactant, the particles change their deposition selectivity from the polyelectrolyte surface to a neutral ethylene glycol monolayer surface. Based on the different selectivity, we have first demonstrated a new approach to direct two component colloidal arrays onto a patterned polyelectrolyte multilayer template.

We report on the optical properties of two dimensional (2D) photonic crystals (PCs) deeply etched in an InP/GaInAsP step-index waveguide. Transmission (T) measurements through simple PC slabs and through one-dimensional (1D) Fabry-Pérot (FP) cavities between PC mirrors are reported and compared to theory. A 2D finite difference time-domain (FDTD) method combined to a phenomenological out-of-plane loss model is used to assess different loss contributions. The PC optical properties are deduced from the FP peak analysis. The origin of the high T level observed inside the stopgap is investigated.

We describe fabrication of sub-micron photonic bandgap structures on Si/SiO2l optical waveguide, which could be used atλ=1.54μm.

We have developed a novel silicon platform where light from optical fiber is coupled directly into and out of silicon-based photonic crystal structures with over 30dB suppression of transmission from 1400nm to 1700nm and defect energy levels tuned to within 2nm in the bandgap. Insertion losses as low as 3.5dB have been achieved. The optical spectra of our one-dimensional silicon-based photonic crystals can be quantitatively described by a simple model of light incident on a series of dielectric interfaces. The agreement between experiment and simulation and the low insertion losses are promising for the future integration of photonic crystals into optical communications.

The effect of microstructures on the photoluminescence of Er2O3thin films has been systematically studied in this paper. The Er2O3 film was fabricated via reactive sputtering of Er metal in an Ar/O2 atmosphere. The as-deposited thin film contained both amorphous and polycrystalline structures, which showed weak photoluminescence at 1.55 µm. Annealing at an elevated temperature from 650 to 1050 °C in O2 ambient significantly incorporated oxygen into the lattice and strongly promoted crystalline grain growth, which in turn dramatically induced the transaction of photoluminescence from 1.55 µm to 1.541 µm. The ideal large crystal Er2O3 structure with fcc-Er2O3 and bcc-Er2O3 precipitates was obtained by conducting a two-step annealing (650 °C for 5 hours followed by 1020 °C for 2 hours) which resulted in a sharp photoluminescence peak at 1.541 µm. Further significant enhancement of PL at 1.541 µm was achieved via RTA at 1050 °C for 30 seconds to introduce more fcc-Er2O3 precipitates into the bcc-Er2O3 matrix.

We obtain the statistics of the intensity, transmission and conductance for scalar electromagnetic waves propagating through a disordered collection of scatterers. Our results show that the probability distribution for these quantities x, follow a universal form, YU(x) = xne−xμ. This family of functions includes the Rayleigh distribution (when α=0, μ=1) and the Dirac delta function (α →+ ∞), which are the expressions for intensity and transmission in the diffusive regime neglecting correlations. Finally, we find simple analytical expressions for the nth moment of the distributions and for to the ratio of the moments of the intensity and transmission, which generalizes the n! result valid in the previous case.

We report optical switching by a silica microsphere optical resonator coated by a conjugated polymer. Microspheres were fabricated by melting the tip of an optical fiber and coated by dipping in a 1 mg/ml toluene solution of poly(2,5-dioctyloxy-1,4-phenylenevinylene) (DOO-PPV). The resonator properties were characterized by evanescently coupling 1.55 µm light propagating along a stripline-pedestal anti-resonant reflecting optical waveguide into optical whispering gallery modes (WGMs). WGM linewidths less than 2 MHz were measured, corresponding to cavity Q > 108. WGM resonant frequency shifts as large as 3.2 GHz were observed when 405 nm pump light with a power density of ~100 mW/cm2 was incident on the microsphere. The time constant of the observed frequency shifts is approximately 0.165 seconds, leading us to attribute the frequency shift to thermo-optic effects. Such a system should be capable of thermo-optically switching at speeds on the order of 10 kHz.

We present fabrication of 3D photonic band gap woodpile crystals from photosensitive chalcogenide glass with the help of interference lithography and layer by layer construction. The alignment method is described, which is scalable to extremely small feature sizes required for photonic crystals in the visible region.

The factors affecting optical gain were studied for Er-doped BaTiO3 thin film waveguides. Er-doped BaTiO3 with dopant concentrations of 0.3 – 9 at.% was deposited by metal-organic chemical vapor deposition. The luminescence efficiency was maximized by optimizing the growth temperatureand erbium concentration as well as by post-deposition annealing. Stimulated emission was studied using the pump-probe technique over the spectral range of 1,520-1,550 nm. A maximum differential gain of 3 dB/cm wasmeasured at 1,540 nm in an 8 mm long, 8 μm wide ridge waveguide.

We review several applications of microstructured photonic crystal optical fibers that incorporate active materials infused into the air-holes. The tunable optical characteristics of the materials combined with the unique structure of the fiber enable a number of functionalities including reconfigurability and tunability for various fiber device applications. We describe a brief characterization of the modes and discuss the experimental results of the fibers.