Measurements of high-speed MSM photodetectors

GaAs MSM photodetectors with AlAs/GaAs DBR structures designed for an operating wavelength of 840 nm were characterized in the frequency and time domains. The frequency response of the MSMs, using a lightwave set-up and HP8408 network analyzer, was measured. The photodetector response to the optical pulse of a fast laser diode excitation was evaluated. 3-dB bandwidth in excess of 4 GHz was obtained. Frequency and pulse responses dependence on photodetector bias was characterized.