Abstract

Photodetectors play a fundamental role in optical communication and measurement systems. In communications systems, faster detectors would enhance system bandwidths, increasing information transmission capacity. In measurement systems, high-speed photodetectors would measure picosecond optical waveforms from mode-locked lasers, and optical and optoelectronic devices. Eventually, the use of fast photodetectors with high-speed sampling electronics could replace autocorrelation and cross-correlation techniques in which the pulse waveform is not directly measured but is inferred using deconvolution methods. To date, the fastest reported photodetectors have been a 4.2 ps FWHM, 110 GHz 3-dB bandwidth GaAs photodiode due to Parker et al. [1]; and, for the longer wavelength regime where InGaAs-based systems must be used, a 3.8 ps FWHM photodiode due to Wey et al. [2]. Because presently available oscilloscopes only have 3-dB bandwidths up to 50 GHz, electro-optic sampling had to be used to measure the response of these photodetectors. The speed of the actual devices was indirectly determined by a deconvolution of the system response from the measured data. To overcome this measurement problem, a high-speed Schottky photodetector has been monolithically integrated with an electronic sampler [3, 4]. Without using deconvolution, we are able to measure a temporal response of 1.8 ps FWHM, corresponding to a 3-dB bandwidth of 200 GHz.

© 1991 Optical Society of America