Advanced receiver technology for commercial threat warning systems
Advanced threat warning technology will begin to play a more significant role for Homeland defense and National security. Of particular concern are landing and take-off patterns of slow moving commercial airliners here and abroad. Recognizing this vulnerability has triggered renewed interest in high sensitivity internal gain optical detectors and 2D arrays. Avalanche photo detectors (APD’s) are the most highly sought after low-noise, high-gain photo sensors. They are being developed for highly sensitive LADAR receiver systems in autonomous munitions and for data communications (for example) and will be the “eyes” of modern commercial threat warning systems. This paper reviews several LADAR technologies and the corresponding requirements placed on APD’s. Performance of commercial and experimental APD’s will be discussed. Recent results on large format InAlAs APD arrays fabricated by the authors will also be presented.
InGaAs/InAlAs avalanche photodiode with undepleted absorber
We report an avalanche photodiode with an undepleted p-type InGaAs absorption region and a thin InAlAs multiplication layer. The motivation for utilizing an undepleted absorption layer, which is similar to that in the unitraveling carrier photodiode, is to reduce the dark current. A dark current below 1 nA at a gain of 10 and a gain–bandwidth product of 160 GHz are demonstrated.
Carnival of Shame: Doctorow and the Rosenbergs
“Literature can turn language, for the moment at least, against the sentence of death.” Considering the national and international furor provoked by the sensational early 1950's “atom spy” trial and execution of Julius and Ethel Rosenberg, one may be surprised that these dramatic and traumatic events have not inspired more literary artistry than they have. But a prominent playwright, Arthur Miller, did write The Crucible (produced in 1953) in part as a response to the rabid McCarthyism of that era, and two highly regarded novelists in a later decade composed ambitious novels drawing directly on the Rosenberg affair: E. L. Doctorow in The Book of Daniel (1971) and Robert Coover in The Public Burning (1977). In 1987, Sidney Lumet produced the little noticed film Daniel, based on Doctorow's novel, and still more recently Tony Kushner's Pulitzer Prize-winning play, Angels in America, with Ethel Rosenberg as one of the characters, has been playing on Broadway.