More Than 20 W, High Signal-to-Noise Ratio Single-Frequency All-Polarization-Maintaining Hybrid Brillouin/Ytterbium Fiber Laser

A high-power all-polarization-maintaining (PM) hybrid Brillouin/ytterbium fiber laser (BYFL) at 1064 nm is demonstrated by adopting large-mode-area fiber with core/cladding diameter of 20/400 µm as the hybrid gain medium. Single-frequency laser output with a record output power of 23 W and an excellent optical signal-to-noise ratio of 72 dB is achieved. The BYFL also presents linear-polarized operation with a polarization extinction ratio of over 16.5 dB, excellent output beam profile and long-term stability. Meanwhile, the relative intensity noise of the Brillouin pump laser is significantly reduced with a maximum factor of 36 dB by the BYFL at the high frequency range, while the corresponding frequency noise is reduced by 15–30 dB across the whole examined frequency range. In addition, the estimated laser linewidth was compressed by 7.8 times from 260 kHz to 33 kHz. To the best of our knowledge, this is the highest output power that emitted from any kind of single-frequency fiber lasers and Brillouin lasers. It is believed that the combination of the hybrid gains and larger mode area fiber provides a promising scheme for realizing further power scaling of a single-frequency laser with all-fiber configuration.