Publications

A design method is presented for contiguous-channel multiplexing filters with many channels covering a wide bandwidth. The circuit topology extends previous work on cochlea-like channelizers by introducing multiple resonator-channel filter sections. The new design provides increased stopband rejection, lower insertion loss, and improved passband shape compared with the earlier version...

Matlab is one of the most commonly used languages for scientific computing with approximately one million users worldwide. Many of the programs written in matlab can benefit from the increased performance offered by multicore processors and parallel computing clusters. The Lincoln pMatlab library (http://www.ll.mit.edu/pMatlab) allows high performance parallel programs to...

The fabrication of reliable InP-based Geigermode avalanche photodiode arrays is described. Arrays of up to 256 x 64 elements have been produced and mated to silicon read-out circuits forming single-photon infrared focal plane imagers for 1.06 and 1.5 mum applications.

Recent years have seen increased interest within the speaker recognition community in high-level features including, for example, lexical choice, idiomatic expressions or syntactic structures. The promise of speaker recognition in forensic applications drives development toward systems robust to channel differences by selecting features inherently robust to channel difference. Within the...

We report an array of Shack-Hartmann wavefront sensors using high-fill-factor Geiger-mode avalanche detector quad cells hybridized to all-digital CMOS counting circuits. The absence of readout noise facilitates fast wavefront sensing at low light levels.

Integrating unmanned aircraft into civil airspace requires the development and certification of systems for sensing and avoiding other aircraft. Because such systems are typically very complex and a high-level of safety must be maintained, rigorous analysis is required before they can be certified for operational use. As part of the...

We report the first high-current photodiode based on the slab-coupled optical waveguide concept. The device has a large mode (5.8 x 7.6 um) and ultra-low optical confinement ([] ~ 0.05%), allowing a 2-mm absorption length. The maximum photocurrent obtained was 250 mA (R = 0.8-A/W) at 1.55 um.

Ever-increasing computing power and connectivity bandwidth, together with falling storage costs, are resulting in an overwhelming amount of data of various types being produced, exchanged, and stored. Consequently, information search and retrieval has emerged as a key application area. Text-based search is the most active area, with applications that range...

Several applications of the Mode S data link are currently being implemented and equipage requirements have been issued in countries around the world. Elementary surveillance (ELS) and enhanced surveillance (EHS) applications have been mandated in Europe with full equipage of all aircraft in the airspace required by 2009. Exemptions to...

We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VpiL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation...