RESUMO
GaNAsSb/GaAs p-i-n photo notdetectors with an intrinsic GaNAsSb photoabsorption layer grown at 350 degrees C, 400 degrees C, 440 degrees C and 480 degrees C, have been prepared using radio-frequency nitrogen plasma-assisted molecular beam epitaxy in conjunction with a valved antimony cracker source. The i-GaNAsSb photoabsorption layer contains 3.3% of nitrogen and 8% of antimony, resulting in DC photo-response up to wavelengths of 1350 nm. The device with i-GaNAsSb layer grown at 350 degrees C exhibits extremely high photoresponsivity of 12A/W at 1.3 microm. These photodetectors show characteristics which strongly suggest the presence of carrier avalanche process at reverse bias less than 5V.
Assuntos
Arsenicais/química , Cristalização/métodos , Gálio/química , Nitrogênio/química , Fotometria/instrumentação , Semicondutores , Transdutores , Temperatura Alta , Nitrogênio/efeitos da radiação , Fotometria/métodos , Ondas de RádioRESUMO
We propose and experimentally demonstrate two optical architectures that process the receive mode of a p x p element phased-array antenna. The architectures are based on free-space propagation and switching of the channelized optical carriers of microwave signals. With the first architecture a direct transposition of the received signals in the optical domain is assumed. The second architecture is based on the optical generation and distribution of a microwave local oscillator matched in frequency and direction. Preliminary experimental results at microwave frequencies of approximately 3 GHz are presented.
RESUMO
We present a new optoelectronic architecture, based on parallel canceled delay lines, that performs programmable filtering of microwave signals. The new architecture can process optically carried microwave signals over frequency bandwidths as large as 20 GHz, with a time-frequency product up to 10(3). The operating principle of this structure is detailed, followed by the preliminary experimental demonstration at 1.2 GHz of a 40-dB rejection filter.