Ultrahigh-speed operation of laser diode by cross-gain modulation using external cavity

An optically controlled laser diode with an intensity- and phase-controllable external cavity was studied in order to achieve an increased bandwidth. The external cavity functions as the feedback section for the laser diode, using time-delayed laser light. A 3-dB bandwidth of over 70 GHz was numerically predicted, using rate equations that include cross-gain modulation and multiple optical feedback from the external cavity. A 3-dB bandwidth of more than 40 GHz was experimentally achieved with a fabricated device.