Narrow-band channel-dropping filter based on side-polished fiber with long interaction length

Abstract

We demonstrate an all-fiber channel-dropping filter comprising a 2 x 2 side-polished fiber coupler with long coupling length and a narrow-band fiber Bragg grating. The side-polished fibers are fabricated on a silicon wafer acting as a polishing substrate while the alignment V-grooves are simultaneously prepared. Two polished fibers with an intracore Bragg grating between them are combined as a grating-frustrated coupler, and a low-loss channel-dropping filter was achieved with the spectral bandwidth less than 2 nm (25 dB), dropping efficiency greater than 98% and channel isolation greater than 25 dB. The filter can be manufactured through a fast and reliable fabrication process.