Publications

We investigate a dim-target-detection approach for pixellated focal-plane-arrays based on differential correlation detection. The change in the temporal correlation of the output signals between an illuminated pixel and a dark reference pixel is measured in real time over some number of samples and may enable more sensitive detection of dim targets whose signal amplitudes are on the order of the noise levels of the sensor. If successful, target detection may be possible with target signal-to-noise-ratios of less than 1 under practical conditions where dark drift may occur. © 2011 SPIE.

We demonstrate the operation of low-power reflective S-SEEDs with 6-ps switching times at a 2-Volt bias. Efficient refractive micro-optics are used to optically interconnect multiple S-SEED gates. The technology platform is expected to enable dense photonic logic circuits for high-speed telecommunications-related applications. © 2009 IEEE.

Functional brain imaging is of great interest for understanding correlations between specific cognitive processes and underlying neural activity. This understanding can provide the foundation for developing enhanced human-machine interfaces, decision aides, and enhanced cognition at the physiological level. The functional near infrared spectroscopy (fNIRS) based event-related optical signal (EROS) technique can provide direct, high-fidelity measures of temporal and spatial characteristics of neural networks underlying cognitive behavior. However, current EROS systems are hampered by poor signal-to-noise-ratio (SNR) and depth of measure, limiting areas of the brain and associated cognitive processes that can be investigated. We propose to investigate a flexible, tunable, multi-spectral fNIRS EROS system which will provide up to 10x greater SNR as well as improved spatial and temporal resolution through significant improvements in electronics, optoelectronics and optics, as well as contribute to the physiological foundation of higher-order cognitive processes and provide the technical foundation for miniaturized portable neuroimaging systems.

Abstract not provided.

We describe recent advances in the development of 1550-nm symmetric self-electrooptic effect devices (S-SEEDs). S-SEEDs are semiconductor optoelectronic devices used to implement ultrafast all-optical logic functions: for optical fiber communication applications. In this paper, basic S-SEED operation is described, followed by a detailed explanation of the optimization techniques used to improve DC and high-speed performance in these long wavelength devices. Both epitaxial strain and quantum well design are shown to be important for S-SEEDs grown in the InAlGaAs quaternary material system. The device fabrication approach is outlined, and DC electrical and optical performance is discussed. Finally, we describe the high-speed optoelectronic measurements used to determine S-SEED switching characteristics. The devices described herein are the first known S-SEEDs to operate at telecommunications- compatible wavelengths and demonstrate record switching speeds with rail-to-rail switching rates faster than 6 picoseconds. © The Electrochemical Society.

This report summarizes a 3-month program that explored the potential areas of impact for electronic/photonic integration technologies, as applied to next-generation data processing systems operating within 100+ Gb/s optical networks. The study included a technology review that targeted three key functions of data processing systems, namely receive/demultiplexing/clock recovery, data processing, and transmit/multiplexing. Various technical approaches were described and evaluated. In addition, we initiated the development of high-speed photodetectors and hybrid integration processes, two key elements of an ultrafast data processor. Relevant experimental results are described herein.

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Sandia National Laboratories has developed a means of manufacturing high precision aspheric lenslet arrays turned on-center. An innovative chucking and indexing mechanism was designed and implemented which allows the part to be indexed in two orthogonal directions parallel to the spindle face. This system was designed to meet a need for center to center positioning of 2μm and form error of λ/10. The part utilizes scribed orthogonal sets of grooves that locate the part on the chuck. The averaging of the grooves increases the repeatability of the system. The part is moved an integral number of grooves across the chuck by means of a vacuum chuck on a tool post that is mated to the part and holds the part while the chuck repositions to receive the part. The current setup is designed to create as many as 169 lenslets distributed over a 3mm square area while holding a true position tolerance of 1μm for all lenslets.

Abstract not provided.