An optically excited microwave ring resonator on a gallium arsenide substrate

An optically excited ring resonator has been fabricated on a GaAs substrate. An optical signal, supplied by a laser diode modulated at microwave frequencies, was focused into a voltage-biased resonator coupling gap to generate carriers from photoconductivity. Results from measurements of the optically generated microwave signal out of the ring resonator revealed resonant peaks at 3.48 GHz, 6.94 GHz, and 10.3 GHz with Q values of 53.5, 75.4, and 103.0, respectively. The output power of the optically driven ring resonator was measured to be -43 dBm at 3.48 GHz, -52 dBm at 6.94 GHz, and -65 dBm at 10.3 GHz. The decrease in output power of the resonator with increasing frequency closely follows the decrease in output power of the modulated laser diode with increasing frequency.<>