Fabrication of single-mode fiber-type polarizer

A simple and novel fabrication technique for a fiber-type polarizer has been developed, and the polarization characteristics of the polarizer have been investigated. The polarizer is formed from a single-mode fiber composed of a concentric core and a silica cladding having a B(2)O(3)-doped silica portion. The cladding is etched off asymmetrically by utilizing the etching-speed difference between pure silica and B(2)O(3)-doped silica in 49% HF. The Al film is subsequently evaporated onto the etched portion. The extinction ratios of polarizers with various buffer-layer thicknesses were measured at two wavelengths, lambda = 1.15 pm and lambda = 1.29 microm. The maximum measured extinction ratio was 37 dB at lambda = 1.29 microm for a 4-cm-long polarizer.