Short-term frequency instability measurement of 2μm single longitudinal-mode laser

The short-term frequency instability of the solid-state laser was measured by using the self-beat of fiber-delay method. The Tm, Ho:YLF microchip laser which was cooled by liquid nitrogen provided with single longitudinal-mode, narrow linewidth output and the power was up to milliwatt. In experiment, at the fixed fiber length of 500 m, self-beat signals of the laser under the integral time about 2 ms, 4 ms, 40 ms, 100 ms were obtained. And under different fiber lengths about 100 m, 200 m, 300 m, 400 m, 500 m, the corresponding time delay is 0.5 μs, 1μs, 1.5μs, 2μs, 2.5μs, and the self-beat signal of the laser was achieved. The short-term frequency instability of Tm, Ho:YLF microchip laser is 1.48 kHz/μs. Meanwhile the relationship between laser frequency stability and laser linewidth is discussed.