Abstract

Efficient high bandwidth photodetectors are of great interest for use in optical communication, as well as in ultrafast measurement techniques. The shortest electrical pulses have been generated from photoconductors, although the quantum efficiency of the sub 10 ps devices has been too low for use in analog or digital transmission experiments. Bandwidths as large as 110 GHz¹ were obtained in GaAs Schottky barrier photodiodes. The shortest measured impulse response was reported by Wang et al.² who measured a photoresponse pulsewidth of 8.8 ps (of which 5.4 ps was attributed to the photodetector). In the long wavelength InGaAs/InP material system, p-i-n diodes have been reported with bandwidths in excess of 58 GHz^3,4. Recently, Crawford et al.⁵ reported the lowest measured impulse response of InGaAs/InP p-i-n photodiodes of 16 ps. In this case, the photodiode response was limited by the measurement system. We have since incorporated a graded double heterostructure into our device structures to minimize carrier diffusion and trapping effects. In this paper, we will present measurements on these photodiodes which have the shortest measured impulse response of any p-i-n or Schottky photodiode yet reported.

© 1991 Optical Society of America