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The ability of biometric systems to enhance personal, business, and national security is clear. They can be used to grant authorized users access to privileged information and protected devices, while [...]

West Virginia University is the only U.S. college offering a degree in biometrics. More than 10 percent of the incoming freshman class of 4,500 students this fall have enrolled in [...]

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.

The problem of face identication in the Mid-Wave InfraRed (MWIR) spectrum is studied in order to understand the performance of intra-spectral (MWIR to MWIR) and cross-spectral (visible to MWIR) matching. The contributions of this work are two-fold. First, a database of 50 subjects is assembled and used to illustrate the challenges associated with the problem. Second, a set of experiments is performed in order to demonstrate the possibility of MWIR intra-spectral and cross-spectral matching. Experiments show that images captured in the MWIR band can be eciently matched to MWIR images using existing techniques (originally not designed to address such a problem). These results are comparable to the baseline results, i.e., when comparing visible to visible face images. Experiments also show that cross-spectral matching (the heterogeneous problem, where gallery and probe sets have face images acquired in dierent spectral bands) is a very challenging problem. In order to perform cross-spectral matching, we use multiple texture descriptors and demonstrate that fusing these descriptors improves recognition performance. Experiments on a small database, suggests that the problem of cross-spectral matching requires further investigation.

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.

Iris recognition has expanded from controlled settings to uncontrolled settings (on the move, from a distance) where blur is more likely to be present in the images. More research is needed to quantify the impact of blur on iris recognition. In this paper we study the effect of out-of-focus blur on iris recognition performance from images captured with out-of-focus blur produced at acquisition. A key aspect to this study is that we are able to create a range of blur based on changing focus of the camera during acquisition. We quantify the produced out-of-focus blur based on the Laplacian of Gaussian operator and compare it to the gold standard of the modulation transfer function (MTF) of a calibrated black/white chart. The sharpness measure uses an unsegmented iris images from a video sequence with changing focus and offers a good approximation of the standard MTF. We examined the effect of the 9 blur levels on iris recognition performance. Our results have shown that for moderately blurry images (sharpness at least 50%) the drop in performance does not exceed 5% from the baseline (100% sharpness).

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.

Techniques for distribution of optical signals, both free space and guided, within electronic systems has been extensively investigated over more than a decade. Particularly at the lower levels of packaging (intra-chip and chip-to-chip), miniaturized optical elements including diffractive optics and micro-refractive optics have received considerable attention. In the case of optical distribution of data, there is the need for a source of optical power and a need for a means of modulating the optical beam to achieve data communications. As the number of optical data interconnections increases, the technical challenges of providing an efficient realization of the optical data interconnections also increases. Among the system signals which might be transmitted optically, clock distribution represents a substantially simplified problem from the perspective of the optical sources required. In particular, a single optical source, modulated to provide the clock signal, replaces the multitude of optical sources/modulators which would be needed for extensive optical data interconnections. Using this single optical clock source, the technical problem reduces largely to splitting of the optical clock beam into a multiplicity of optical clock beams and distribution of the individual clocks to the several portions of the system requiring synchronized clocks. The distribution problem allows exploitation of a wide variety of passive, miniaturized optical elements (with diffractive optics playing a substantial role). This article reviews many of the approaches which have been explored for optical clock distribution, ranging from optical clock distribution within lower levels of the system packaging hierarchy through optical clock distribution among separate boards of a complex system. Although optical clock distribution has not yet seen significant practical application, it is evident that the technical foundation for such clock distribution is well established. As clock rates increase to 1 GHz and higher, the practical advantages of optical clock distribution will also increase, limited primarily by the cost of the optical components used and the manufacturability of an overall electronic system in which optical clock distribution has been selectively inserted.

We describe the design and lasing characteristics of a miniaturized, chip-scale Nd:YAG slab laser. The Nd:YAG laser slab utilizes a retroreflecting corner to achieve a 17-cm optical path length with slab geometry of 10×12×2 mm. The laser is constructed, tested, and shown to successfully lase at 1064 nm under edge pumping with an AlGaAs diode laser at 808 nm. The slab laser is operated in a pulsed-pump excitation mode and shown to support a TEM10 single output mode. The fluence achievable from the edge pumping of this initial cavity geometry results in a 6.0&percent; experimentally measured lasing efficiency.