All fibre, 1.5 mu m widely tunable single frequency and narrow linewidth semiconductor ring laser with fibre Fabry Perot filter

An all fibre, widely tunable, single frequency, semiconductor ring laser was constructed with a narrow linewidth of 35 kHz. Tuning over 50 nm was electronically obtained using a fibre Fabry-Perot filter as a selected wavelength element. Single-frequency operation was demonstrated with sidemode suppression higher than 35 dB.