Periodically stressing a birefringent fiber once per beat length can cause coherent coupling to occur between polarization modes. Such a birefringent-fiber polarization coupler is described here. More than 30 dB of power transfer between polarizations has been achieved. The device has been used as the output coupler of an in-line Mach–Zehnder interferometer, and better than 25-dB on/off extinction has been measured. The device is wavelength selective and can be used as a multiplexer or as a notch filter. A notch of 9-nm full width at half-maximum has been achieved with a 60-period comb structure.
© 1983 Optical Society of America
R. C. Youngquist, J. L. Brooks, and H. J. Shaw, "Birefringent-fiber polarization coupler," Opt. Lett. 8, 656-658 (1983)