We demonstrate both numerically and experimentally that rare-earth-doped twin-core fiber couplers can function as a narrow-bandpass wavelength filter or as a demultiplexer. The experimental bandwidth obtained is 6.5 nm. In addition, the filtered signal experiences a gain of 20 dB instead of attenuation.
© 1993 Optical Society of America
B. Wu and P. L. Chu, "Narrow-bandpass filter with gain by use of twin-core rare-earth-doped fiber," Opt. Lett. 18, 1913-1915 (1993)