Picosecond GaAs-Based Photoconductive Optoelectronic Detectors

Abstract

Picosecond photoconductive-switch performance was demonstrated with a novel material deposited by molecular beam epitaxy at low substrate temperatures using Ga and As4 beam fluxes. For a photoconductive-gap switch fabricated on a coplanar transmission line, the speed is 1.6 ps (full width at half maximum) and the voltage response is 10 to 100 times greater than that of conventional photoconduc­tive switches. Since LT GaAs is compatible with GaAs device and IC technologies, this photoconduc­tive switch may find extensive use in high-speed device and circuit testing.

Optoelectronic measurement of the transfer function and time response of a 70 GHz sampling oscilloscope

“…Ultrafast electrical test pulses are generated in a photoconductive switch that is fabricated from lowtemperature grown GaAs [9] and incorporated into a coplanar waveguide (CPW). The centre stripe of the waveguide is 30 µm broad and separated by 20 µm from the 500 µm broad ground stripes.…”

“…Ultrafast sampling oscilloscopes are usually characterized with an optoelectronic measurement set-up [7,8] that uses photoconductive switches for the generation of picosecond electrical pulses [9]. If such a broadband calibration pulse is applied to the input connector of the oscilloscope, the complex transfer function of the oscilloscope can be determined given that the time trace of the calibration pulse is well known.…”