Electromechanically Induced GHz Rate Optical Frequency Modulation in Silicon

We present a monolithic silicon acousto-optic frequency modulator (AOFM) operating at 1.09 GHz. Direct spectroscopy of the modulated laser power shows asymmetric sidebands, which indicate coincident amplitude modulation and frequency modulation (FM). Employing mechanical levers to enhance the displacement of the optical resonator resulted in greater than 67X improvement in the optomechanical FM factor over earlier reported numbers for silicon nanobeams.