Publications

Abstract not provided.

Abstract not provided.

A new type of GaAs laser is based on the electron-hole plasma in a current filament and is not limited in size by p-n junctions. High energy, electrically controlled, compact, short-pulse lasers are useful for: active optical sensors (LADAR, range imaging, imaging through clouds, dust, smoke, or turbid water), direct optical ignition of fuels and explosives, optical recording, and micro-machining. The authors present a new class of semiconductor laser that can potentially produce much more short pulse energy than conventional (injection-pumped) semiconductor lasers (CSL) because this new laser is not limited in volume or aspect ratio by the depth of a p-n junction. They have tested current filament semiconductor lasers (CFSL) that have produced 75nJ of 890nm radiation in 1.5ns (50W peak), approximately ten times more energy than ISL. These lasers are created from current filaments in semi-insulating GaAs and, in contrast to CSL, are not based on current injection. Instead, low-field avalanche carrier generation produces a high-density, charge-neutral plasma channel with the required carrier density distribution for lasing. They have observed filaments as long as 3.4cm and several hundred microns in diameter in the high gain GaAs photoconductive switches. Their smallest dimension can be more than 100 times the carrier diffusion length in GaAs. This paper will report spectral narrowing, lasing thresholds, beam divergence, temporal narrowing, and energies which imply lasing for several configurations of CFSL. It will also discuss active volume scaling based on recent high current tests.