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Although human iris pattern is widely accepted as a stable biometric feature, recent research has found some evidences on the aging effect of iris system. In order to investigate changes in iris recognition performance due to the elapsed time between probe and gallery iris images, we examine the effect of elapsed time on iris recognition utilizing 7,628 iris images from 46 subjects with an average of ten visits acquired over two years from a legacy database at Clarkson University. Taken into consideration the impact of quality factors such as local contrast, illumination, blur and noise on iris recognition performance, regression models are built with and without quality metrics to evaluate the degradation of iris recognition performance based on time lapse factors. Our experimental results demonstrate the decrease of iris recognition performance along with increased elapsed time based on two iris recognition system (the modified Masek algorithm and a commercial software VeriEye SDK). These results also reveal the significance of quality factors in iris recognition regression indicating the variability in match scores. According to the regression analysis, our study in this paper helps provide the quantified decrease on match scores with increased elapsed time, which indicates the possibility to implement the prediction scheme for iris recognition performance based on learning of impact on time lapse factors.

Two-dimensional, nano-scale photonic crystals (PhCs) in silicon and biocompatible polymer materials, such as: Polydimethylsiloxane (PDMS) and epoxy, are potential core structures in ultra-sensitive biosensors enhancing fluorescence emission in the near IR and visible range. A triangular PhC lattice (r/a = 0.33) of silicon pillars suspended in toluene was designed to enhance emission in the near-IR range. We present here a 27-fold enhancement of PbS-Quantum-Dot emission at 1100 nm. Moving to more biocompatible materials, we also present frequency-domain modeling results demonstrating partial photonic bandgaps for triangular PhC lattices in PDMS and epoxy. The existence of these bandgaps suggests that PhCs in polymer materials could potentially enhance visible-range fluorescence emission and become co-integrated with other on-chip components, such as microfluidic channels and optical waveguides, to produce cost-effective biosensors.

The combination of optics and microfluidics into optofluidic systems has provided a means of creating portable integrated platforms for performing fluorescence emission analyses in fieldable systems. We present here the design of a photonic crystal transducer for highly sensitive and selective fluorescence-based biomolecule detection using a reduced-size lattice nanocavity tuned for resonance at emission wavelengths. This novel approach to biosensing is based upon photonic crystal defect structures that are engineered to act as waveguides, optical resonant cavities, and nanofluidic flow channels. This paper will discuss modeling, design, and nanofabrication of optofluidic photonic crystal (PhC) transducers in silicon and GaN materials. First-order results of PhC optical property characterization will be provided. Preliminary simulations indicate that fluorescence emission intensity inside of a PhC resonant defect nanocavity is enhanced to a level 26 times greater than emission outside of a defect due to resonant optical confinement and the Purcell effect.

Periodic poling of GaN (alteration of the crystallographic direction along the c-axis) has potential for applications in photonics, sensing, and non-linear optics. One approach to periodic poling of GaN, involves Molecular Beam Epitaxy (MBE) growth of heavily Mg doped GaN which results in inversion of the surface polarity from Ga-polar to N-polar GaN. Fabrication and dry etching of the inversion layer followed by re-growth, and a subsequent highly anisotropic wet etch of re-grown N-polar regions can result in periodically poled GaN with features on either the micro or nanoscale. This paper outlines the design of GaN based photonic crystal biosensors based on periodic poling. Initial results of growth, fabrication, and theoretical modeling will be discussed.

Discusses compatibility problems presented by the integration of gallium arsenide (GaAs) optoelectronic devices and silicon microelectronic devices that could degrade silicon complementary metal oxide semiconductor (CMOS) performance. GaAs-on-silicon growth; Compatibility study; Device mobility and threshold voltage; Gate oxide reliability.

While the advantages of optical over electrical interconnects for conventional 2-D VLSI and wafer-scale-integrated (WSI) circuits have not been clearly demonstrated, for 3-D interconnection structures such as those necessary for stacked wafer and similar architectures, the trade-off between using optical or electrical methods for vertical links is not straightforward. Current work on fabricating a through-wafer optical interconnect within a hybrid-WSI environment is motivated by the need to obtain experimental data on the overall performance of an optical interconnect so that this trade-off can be clarified in the case of hybrid-WSI and in the general case at least more well defined. This paper details the design and fabrication of SiO_2 Fresnel phase plate lens arrays for use in the experimental 1.3-μm wavelength through-wafer optical interconnects to be constructed. These 0.8-N.A. lenses have submicron minimum linewidths and are VLSI process compatible. Preliminary results are presented indicating that, with the use of these lens arrays, vertical optical interconnect densities comparable with that of on chip bonding pads (≈250-μm pitch) are obtainable within these architectures.