Optically excited microwave ring resonators in gallium arsenide

Microstrip ring resonators with fundamental frequencies near 3.5 GHz have been fabricated in semi-insulating GaAs using an electroplating technique for conductor deposition. Test signals were coupled into the resonators by focusing modulated light into a photoconductive microstripline gap. Loaded Q-factors measured for one of the rings with optical excitation ranged from 54 at the fundamental frequency to 103 at the third harmonic.