Broadband mid-IR chalcogenide fiber couplers

Abstract

We demonstrate a broadband As₂S₃-based fiber coupler operating up to the 5.4 μm wavelength range developed by using a fused biconical tapering technique. During the manufacturing process, real-time data monitoring of the coupling ratio was at 2.64 μm. The measurement of minimal excess loss was at less than 1 dB in the range of 5-5.4 μm. Also, fiber bend loss was numerically analyzed to determine optimal coupler geometric parameters.