Measurement of the fundamental modulation response of a semiconductor laser to millimeter wave frequencies by active-layer photomixing

The room-temperature modulation response of a GaAs/GaAlAs semiconductor laser (relaxation resonance frequency, vR=6.5 GHz) is measured to 37 GHz using the active-layer photomixing technique. The measured response function agrees with the theoretical ideal, and there is no indication of device parasitic effects. An ultrahigh-finesse Fabry–Perot interferometer is used to detect the optical modulation, which appears as sidebands in the laser field spectrum. With a moderately faster laser diode (i.e., vR~10 GHz), the modulation response should be measurable beyond 100 GHz