Chalcogenide optical fiber couplers made by FBT method

We report on developing and characterization of chalcogenide FBT single mode fiber coupler for Mid-IR fiber optics applications. Single mode 6.3 μm core/123 μm cladding chalcogenide fibers of IHPS RAS with homemade polishing and standard PC/AFC connectors were utilized. Two fiber coupler geometries with angles α1 = 70° and α2 = 40° between the fibers were investigated and nature of excess loss has been studied. Excess loss and coupling ratios on time for both geometries were determined. Excess losses were measured to be 7 dB and 5 dB for α1 and α2 geometries respectively. For α1 geometry 70:30 and for α2 geometry 55:45 coupling ratios were achieved. For α2 geometry coupling ratio at wavelength 2.64 μm was 63:37.