Single- and dual-wavelength ultra-narrow linewidth fiber lasers based on a guided-mode resonance reflector

摘要

A stable, single- and dual-wavelength, single-longitudinal-mode operation ring erbium-doped fiber laser with ultra-narrow linewidth and high optical signal to noise ratio is proposed and demonstrated experimentally. Different from using traditional fiber Bragg gratings as narrow band filters, a guided-mode resonance reflector with high quality value, fabricated on a silicon-on-insulator wafer, acts as an external reflector to realize optical feedback and wavelength selectivity in the fiber laser. Using unpumped erbium-doped fiber as a saturable absorber, different areas of the guided-mode resonance reflector as mode restricting elements, we obtain a single-wavelength laser with optical signal to noise ratio over 67 dB and ultra-narrow linewidth of 525 Hz, and a dual-wavelength laser with optical signal to noise ratios higher than 61 dB and linewidths less than 800 Hz for both lasing wavelengths. Meanwhile, all the central wavelength variations and power fluctuations of the laser are less than 0.024 nm and 0.106 dB, respectively, showing favorable stability.