Publications

An asynchronous readout integrated circuit (ROIC) has been developed for hybridization to a 32x32 array of single-photon sensitive avalanche photodiodes (APDs). The asynchronous ROIC is capable of simultaneous detection and readout of photon times of arrival, with no array blind time. Each pixel in the array is independently operated by...

We have developed and demonstrated a highduty- cycle asynchronous InGaAsP-based photon counting detector system with near-ideal Poisson response, roomtemperature operation, and nanosecond timing resolution for near-infrared applications. The detector is based on an array of Geiger-mode avalanche photodiodes coupled to a custom integrated circuit that provides for lossless readout via...

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.

Arrays of InP-based avalanche photodiodes (APDs) with InGaAsP absorber regions have been fabricated and characterized in the Geiger mode for photon-counting applications. Measurements of APDs with InGaAsP absorbers optimized for 1.06 um wavelength show dark count rates (DCRs)

We consider the phenomenon of afterpulsing in avalanche photodiodes (APDs) operating in gated and free-running Geiger mode. An operational model of afterpulsing and other noise characteristics of APDs predicts the noise behavior observed in the free-running mode. We also use gated-mode data to investigate possible sources of afterpulsing in these...

Accurate circuit models derived from electromagnetic simulations have been used to fabricate photomixer sources with optimized high-impedance antennas. Output powers on the order of 1 uW were measured for various designs spanning 0.6-2.7 THz. The improvement in output power ranged from 3 to 10 dB over more conventionally designed photomixers...

We report the first successful demonstration of a photomixer local oscillator (LO) integrated with a superconducting heterodyne detector. The photomixer LO generated the difference frequency of two diode lasers by optical heterodyne conversion in low-temperature-grown GaAs. The measured receiver noise temperature, 331 K at 630 GHz, compares favorably with that...

A photomixer local oscillator (LO) operating at the 630-GHz difference frequency of two laser diodes was successfully demonstrated with a heterodyne detector based on a niobium superconducting tunnel junction. The low-temperature-grown GaAs photomixer generated 0.20 uW in the input spatial mode of the receiver. Using the photmixer LO, the double-sideband...