Abstract

Research in the use of radiation damaged semiconductors^[1] as picosecond photoconducting pulse generator, and sampling gates has led to the identification of material systems where subpicosecond^[2] free carrier relaxation times along with reasonably high free carrier mobilities and material dark resistivities can be realized. However, on such small time scales these optoelectronic autocorrelation measurements are limited by the speed of response of the microstrip circuits used^[3]. A recently described measurement scheme^[4] overcomes such circuit limitations to the response speed by utilizing picosecond photoconductors as radiating and receiving dipole antennas. In such Hertzian dipole experiments no transmission line structures are used to couple the electrical pulse generator to the sampling gate; instead, the picosecond electromagnetic pulse from the pulse generator is radiated freely through a bulk dielectric medium to the receiving photoconductor, which acts as a picosecond sampling gate. This results in a high pass coupling scheme, as opposed to the low pass transfer characteristics of microstrip interconnections.

© 1985 Optical Society of America