Acousto-optic tunable bandpass filter based on acoustic-flexural-wave-induced fiber birefringence

An acousto-optic tunable bandpass filter was proposed and fabricated based on acoustic-flexural-wave-induced single-mode fiber birefringence via coupling the core mode to a single-cladding vector mode. In the experiment, the resonant wavelength and insertion loss could be electrically tuned with a span of nearly 100 nm and a lowest insertion loss of −1.7 dB. The structure gains advantages of a large tuning range, fast speed, easy fabrication, low insertion loss, and zero frequency shift.