Demonstration of a stable and uniform single-wavelength erbium-doped fiber laser based on microfiber knot resonator

<p> We propose and demonstrate an application of microfiber knot resonator (MKR) in the generation of a stable and uniform single-wavelength erbium-doped fiber laser (EDFL). An MKR was fabricated using a microfiber a few micrometers in diameter. By embedding the MKR to the ring cavity of the EDFL, a laser with a wavelength of 1558.818&nbsp;nm and a 3-dB linewidth of 0.0149&nbsp;nm is demonstrated. The side mode suppression ratio of the laser is about 30&nbsp;dB, and the maximum power fluctuation is about 0.85&nbsp;dB. The results demonstrate that the MKR can be employed as a high-performance comb filter to realize a stable and uniform fiber laser.</p