University of Michigan

Joungho Kim

Gerard A Mourou

Joo-Hiuk Son

A photoconductive method or apparatus for measuring high frequency signals using a relatively inexpensive photoconductive material with a relatively long duration or recombination time. The photoconductive method or apparatus utilizes a photoconductive element of photoconductive material such that the duration or recombination time of the photoconductive material is longer than the pulse width of the signal to be measured. As such, the photoconductive element produces a step function response to the signal to be measured rather than a rectangular response with respect to the signal to be measured. The photoconductive element avoids the need to sacrifice measurement sensitivity by introducing defects in the photoconductive material to shorten the recombination time or duration. The measurement bandwidth of the photoconductive element is not limited by the recombination time of the photoconductive material which is mostly dominated by the carrier lifetime. The measurement bandwidth for the photoconductive element is limited by the pulse width of the optical signal driving the photoconductive element which can be very short duration thereby providing improved resolution. As such, the photoconductive element can comprise a cheaper photoconductive material which has a longer duration or recombination time but with a higher sensitivity and improved measurement resolution.

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Seoul, South Korea

Joungho Kim