Garrett J. Schneider

Dispersion-based optical routing in photonic crystals

We present and experimentally validate self-collimation in planar photonic crystals as a new means of achieving structureless confinement of light in optical devices. We demonstrate the ability to arbitrarily route light by exploiting the dispersive characteristics of the photonic crystal. Propagation loss as low as 2.17 dB/mm is observed, and proposed applications of these devices are presented.

Self-collimation in photonic crystal structures: a new paradigm for applications and device development

In this paper, we report on the development of the self-collimation phenomenon in photonic crystal structures for integrated optics applications. In addition, detailed numerical analysis, design procedures, fabrication and characterization techniques are included. Applications presented in this paper include: channelless waveguiding, orthogonal bending of light, tunable beam splitter, all-optical analog-to-digital converter, reconfigurable optical switch, chemical/gas sensor and a three-dimensional optical interconnect bus.

Photonic Crystal Structures and Applications: Perspective, Overview, and Development

In this paper, we present an overview of milestone achievements in the research and development of photonic crystal structures and their perspective applications. We highlight challenges in the analysis techniques, device design, efficient coupling techniques, and fabrication and characterization techniques for both planar and three-dimensional structures. We discuss extensively progress to date to overcome various aspects in the available modeling and simulation tools as well as the necessary fabrication procedures to produce functional photonic crystal structures and devices. Hence, the goal of the work presented in this paper is to present key building blocks, which will in turn facilitate the full utilization of the unique spatial and temporal properties of photonic crystal structures

Wavelength scale terahertz two-dimensional photonic crystal waveguides

A terahertz-scale two-dimensional photonic-crystal waveguide based on a silicon-on-insulator was fabricated, and the optical transmission spectrum was measured. Terahertz beam propagation characteristics were observed using a thermal imaging camera, with incident light in the 10.1-10.7 microm range. The measured transmission spectrum was in good agreement with a three-dimensional finite-difference time-domain calculation.

Nonlinear optical spectroscopy in one-dimensional photonic crystals

We have conducted a spectroscopic investigation of the enhancement of nonlinear optical effects around a defect in a one-dimensional photonic crystal. Degenerate four-wave mixing studies were performed on a dielectric stack that contained a polymer thin-film defect layer doped with a nonlinear organic dye. This sample exhibited a large nonlinear response at a resonant defect frequency. Nonlinear spectroscopy was performed around the defect resonance and at frequencies well away from resonance. We have shown that the four-wave mixing signal exhibits extremely high-quality resonance, consistent with the expected cubic dependence on the calculated intensity within the defect layer.

Radiometric Millimeter-wave detection via optical upconversion and carrier suppression

We report a novel technique for radiometric detection of radiation in the millimeter-wave regime based on optical modulation. Millimeter-wave energy modulated onto an optical carrier is detected using a low-bandwidth photodetector with optical filtering to suppress the carrier. Using this technique, we have achieved noise-equivalent powers as low as 20 pW/spl radic/Hz for a 44-GHz narrow-band signal using chopping techniques. Such detection was implemented using commercially available components and without RF or optical amplification. Further improvements in sensitivity are expected as the setup is optimized for operation in the frequency band of interest.

Subwavelength imaging by a flat cylindrical lens using optimized negative refraction

We experimentally demonstrate subwavelength imaging by a “flat cylindrical” lens using negative refraction. A two-dimensional photonic crystal whose dispersion at the second band provides group velocity opposite to the phase velocity for electromagnetic waves is employed to realize the flat lens, and the working frequency is chosen so that the effective refractive index is approximately equal to −1.0. Experiment demonstrated the imaging of a point source in both amplitude and phase in the millimeter-wave regime. By measuring the field distributions in the object plane and image plane, we observed amplification of evanescent waves and subwavelength size image. The image of two incoherent sources with subwavelength distance showed two resolvable spots, which served to further verify subwavelength resolution.

Defect modes in coaxial photonic crystals

One-dimensional (1D) photonic crystals have been constructed by connecting segments of coaxial cable of differing characteristic impedance. Impurities have been introduced into these crystals by inserting cable segments to break the crystal symmetry. This system provides a simple way to study 1D photonic band structure effects with complete control over impurities in the lattice. We have studied the effects of the size, number, and location of defects in the lattice. We have also measured directly the concentration of energy in the steady-state electromagnetic fields within doped crystals, and observed the influence of the defects on the phase (dispersion). A modified dielectric stack model was developed to describe this system, with the results in excellent agreement with our measurements. Our findings compare favorably to previously published measurements of transmission and phase change in three-dimensional photonic crystals.

Three-dimensional lithographical fabrication of microchannels

With the rapid development of microfluidic systems, there is high demand for fabrication methods for the fluidic components that can be used to realize complex three-dimensional (3-D) geometries, high integration levels, full compatibility with sensing and controlling circuits, and possess batch fabrication capability. In this paper, we propose and demonstrate such a method based on a novel 3-D lithography technique. The method employs commercially available photoresist and standard lithography facilities. Single-level microchannels with micron-size cross sections up to 1.2 mm in length, as well as multilevel channels with unique 3-D structures, have been fabricated using the proposed method. This method allows direct postintegration of microchannels with previously fabricated integrated circuits without etching, bonding or additional material deposition except resist spin coating. Using this method, the fabrication of microchannels can be greatly simplified, and many unique 3-D topologies beyond the ability of current techniques can be obtained.

Fabrication of three-dimensional photonic crystalsusing silicon micromachining

We propose a method for the fabrication of three-dimensional photonic-crystal structures using conventional planar silicon micromachining. The method utilizes a single planar etch mask coupled with time-multiplexed, sidewall-passivating, deep anisotropic reactive-ion etching, to create an array of spherical voids with three-dimensional symmetry. Preliminary results are presented that demonstrate the feasibility of the approach.