We report a multiple quantum well ridge guide laser tuned by the quantum confined Stark effect. In contrast to carrier-induced effect tuned lasers, the frequency modulation response of our laser is highly uniform(±0.7 dB)over the frequency range from 10 kHz to 100 MHz, and within±2.5 dBfrom 5 kHz to 500 MHz, with the upper frequency parasitic capacitance limited. We predict that the response could be extended to over 20 GHz by using a low parasitic contacting structure. ©1997 American Institute of Physics.