1.5 μm coupled-cavity passively Q-switched self-Raman laser

A compact, eye-safe, passively Q-switched self-Raman laser operating at 1.5 μm was demonstrated for the first time, to our knowledge, using a coupled-cavity architecture. This configuration ensures high coupling conversion efficiency and enables sub-nanosecond pulse generation while eliminating the need for complex multi-wavelength coatings and reducing the risk of optical damage to the V:YAG saturable absorber at 1.5 μm. Burst-mode operation with a controllable number of pulses was achieved by adjusting the pumping width. At a pumping width of 11.2 μs, single-pulse Raman emission was obtained, delivering a pulse energy of 28.60 μJ and a pulse width of 0.99 ns at a pulse repetition frequency of 5 kHz, corresponding to an optical conversion efficiency (from 808 nm to 1.5 μm) of 4.14%, a peak power of 28.89 kW, and a beam quality with M² factors better than 1.15. This compact passively Q-switched self-Raman laser, featuring narrow pulse width and excellent beam quality, exhibits significant potential for applications in LiDAR, laser ranging, and illumination.