A prototype of a new design of fiber frequency shifter, based on a special four-port fused taper coupler with a null maximum coupling ratio, is reported. In this coupler the constituent fibers are so dissimilar that the maximum coupling is (ideally) zero. In the presence of a flexural acoustic wave, light is coupled between the fibers, acquiring a frequency shift in the process. Near 100% conversion with 30-dB sideband and carrier suppression is achieved, in an unoptimized device, for just 1 mW of electrical drive power.
© 1994 Optical Society of America
Original Manuscript: March 10, 1994
Published: December 1, 1994
T. A. Birks, S. G. Farwell, P. St. J. Russell, and C. N. Pannell, "Four-port fiber frequency shifter with a null taper coupler," Opt. Lett. 19, 1964-1966 (1994)