Microwave signal generation using a standing-wave surface-acoustic-wave Bragg device

Guided-wave acousto-optic (AO) devices using surface-acoustic-waves (SAWS) and optical waveguides have many applications. One possible employment is in a Bragg standing-wave surface-acoustic-wave (SW-SAW) device. The SW-SAW Doppler shifts the optical beam both up and down by the acoustic frequency. Thus, upon detection, the beat frequency of the two coherent Doppler shifted beams effectively generates a carrier for the optical signal at twice the acoustic frequency. The generation of carriers by heterodyning two copropagating optical beams has been dubbed Double Beam Modulation (DBM). Previously carriers in the hundreds of MHz have been demonstrated with this technique using both bulk and guided-wave acousto-optic devices.[l] The use of a guided-wave acousto-optic device has been extended into the GHz range.