Spectral Narrowing and Stabilization of Thulium Fiber Lasers using Guided Mode Resonance Filters

摘要

Guided mode resonance filters (GMRF) were used to spectrally-stabilize and line-narrow the output spectrum from Tm fiber lasers operating in the 2 μm wavelength regime. The GMRFs were placed in the output path of an amplified spontaneous emission (ASE) light source and the transmitted light was measured as a notch in the spectrum on resonance. The GMRFs were characterized to determine their peak reflectivity, resonance wavelength, and spectral linewidth of each element. These measurements showed various resonance wavelengths and linewidths varying from 0.50-1.5 nm depending on the individual GMRF parameters. Using GMRFs as feedback elements in Tm fiber laser oscillators resulted in output powers up to 10 W and slope efficiencies of 30-45% with respect to launched 790 nm pump power. In order to scale to higher powers and maintain narrow linewidths, a master oscillator power amplifier (MOPA) setup was employed with a GMRF stabilized master oscillator. In addition to the laser and amplifier characteristics, thermal and damage testing of the GMRFs is reported.