Bandwidth measurements of ultrahigh-frequency optical detectors using the interferometric FM sideband technique

A frequency modulated semiconductor laser and an interferometer are used as a source of very high frequency amplitude modulation to measure the response of optical detectors. This new technique does not require a laser with a flat, or even known, frequency response, and measures the detector response at frequencies well above the modulation frequency applied to the laser. The response of several InGaAs p-i-n detectors has been measured to 22 GHz using 1.3- and 1.55-μm semiconductor lasers modulated at only 500 MHz. These measurements were not limited by the measurement method, which may be capable of measuring bandwidths substantially in excess of 20 GHz.