Dual-wavelength narrowband all-fiber acousto-optic tunable bandpass filter based on dispersion-compensating fiber

A dual-wavelength narrowband all-fiber acousto-optic tunable bandpass filter was proposed and fabricated based on vector mode coupling induced by the acoustic flexural wave in dispersion-compensating fiber with a ring core. In the experiment, the resonant dual wavelengths could be electrically tuned with a range of 1526nm to 1565nm and the 3 dB bandwidth was less than 1nm, which coincides with the calculation results. The structure shows the advantages of fast tuning speed, easy fabrication, and zero frequency shift, which can be applied in fast-tunable dual-wavelength lasers, WDM networks, and microwave and terahertz-wave generation.