Polarization maintain fiber couplers with novel transmission characteristics

we report theoretical and experimental investigations into a polarization maintain fiber (PMF) coupler with novel transmission characteristics. The experimental results show that for circular and elliptically polarized input light, the novel coupler will act as an in-line polarizer and as a conventional fused-taper PMF coupler, the output polarization extinction ratio (PER) of the transmission arm is 31dB at a wavelength of 845nm. For linearly polarized input light, the coupler will merely act as a conventional 3dB PMF coupler. This novel device can be widely used in optical sensor systems, such as fiber optical gyroscopes, fiber optical hydrophones, and fiber optical current sensors, etc.