Tunable erbium fiber laser using a novel overlay bandpass filter

A unidirectional erbium fiber laser incorporating a novel LiNbO(3) overlay fiber-optic bandpass filter is demonstrated. By applying index-matching oils of different refractive indices to the surface of the overlay filter, we could tune the operating wavelength of the laser from 1531 to 1556 nm while maintaining a bandwidth of less than 0.2 nm (resolution limited). Output powers as high as 3 mW for 36 mW of pump power have been recorded.