A broadly tunable wavelength-selectable WDM source using a fiber Sagnac loop filter

We describe a new discretely wavelength-selectable 1.5-μm source based on the use of a fiber Sagnac loop filter leading to the possibility of an efficient all-fiber source. The filter has an /spl sim/1.6-dB insertion loss, 14-dB peak-to-valley transmission ratios, and can be tuned to a very precise match with the International Telecommunications Union-wavelength-division-multiplexing grid. We demonstrate 25-channel outputs with precise 50-GHz channel spacings and very large (65 dB) output signal to background noise ratios.