2051 nm Narrow Linewidth All-Fibre DFB Laser for Holmium-Doped Fibre-Amplifier Applications

We report the design and performance of a single frequency all-fibre 2051 nm distributed feedback (DFB) laser source employing fibre Bragg gratings (FBGs). Output powers up to 36 mW CW and optical signal-to-noise ratios of > 65 dB/0.05 nm are obtained. Heterodyne measurements yield laser linewidths of ∼130 kHz FWHM. The single frequency source is amplified with a polarization-maintaining Ho-doped fibre amplifier (HDFA) to an output power of 1 W CW.