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With the development of the laser and its enormous bandwidth capabilities, the simultaneous development of the photosensing devices has proceeded. A photodiode is one of these devices and shows great promise due to its inherent sensitivity, ruggedness, and the ability to obtain large internal gain. Because of this, many photodiodes have been built with responses into the microwave region. These devices have extremely small active areas and low quantum efficiencies, as with a point contact photodiode. This paper discusses the problems of building a large area high frequency photodiode and how they were overcome. The theoretical considerations for using a free-running inhomogeneously broadened laser to obtain a millifrequency signal to test the photodiodes are discussed in some detail. These results have been used to obtain the frequency response of the photodiodes.

The broad purpose of the research activity reported herein is to extend the useful frequency spectrum into the range from microwave frequencies to optical frequencies and to improve existing devices and techniques in the microwave spectrum. At present this objective is being pursued by studies of electron beam devices, quantum electronic devices, plasmas, and solid-state devices. (Author)