A single-frequency 1064-nm Yb3+ -doped fiber laser tandem-pumped at 1018 nm

In this study, a single-frequency 1064-nm Yb fiber laser tandem-pumped at 1018 nm is demonstrated for the first time. The single-frequency operation of 1064 nm laser is achieved by means of a unidirectional ring cavity together with an unpumped active fiber served as a saturable absorber (SA). A maximum single longitudinal mode (SLM) output power of 231 mW was obtained under the 1018-nm pump power of 1.4 W. The signal-to-noise ratio, spectral linewidth, and relative intensity noise were 72 dB, 1.4 kHz, and –141 dB/Hz, respectively. The spectral linewidth of 1064-nm single-frequency output under 1018-nm pumping was narrowed significantly in comparison with that under 976-nm pumping. Additionally, the laser performance under single- and multi-longitudinal-mode (MLM) 1018-nm pump light was investigated. The result revealed that the SLM pump helped improve the behavior of noise.