Few-layer TiSe as a saturable absorber for nanosecond pulse generation in 2.95 μm bulk laser.

1T-phase titanium diselenide (1T-TiSe), a model two-dimensional (2D) transition metal dichalcogenide, has attracted much attention due to its intriguing electrical and optical properties. In this work, a 1T-TiSe-based high-quality large-area saturable absorber (SA) (1T-TiSe-SA) was successfully fabricated with the liquid-phase exfoliation method. With the as-prepared 1T-TiSe-SA, a stable, passively Q-switched laser operating at 2.95 μm was first realized. Under an absorbed pump power of 3.35 W, the maximum average output power was 130 mW with a slope efficiency of 5%. A pulse width of 160.5 ns was obtained, which is the shortest among 3.0 μm passively Q-switched lasers ever achieved with 2D materials as SAs, to the best of our knowledge. The results indicate that 1T-TiSe is a promising alternative as a nonlinear optical modulator for short-pulse laser generation near the 3.0 μm mid-infrared region.