Self-Q-switched mid-infrared laser operation with a novel Er, Pr: GYAP crystal

We demonstrate a self-Q-switched polarized mid-infrared laser based on a novel Er,Pr:GYAP crystal. The structure, thermal, spectroscopy and laser performance are systematically studied. The crystal exhibits high quality with a narrow X-ray rocking curve (FWHM of 0.014°). A broad absorption band around 971 nm and multiple strong emission peaks at 2.5–3.0 μm are observed. The emission and absorption cross-sections of Er,Pr:GYAP crystal in the range of 2500–3000 nm are calculated. The level lifetimes of Er3+:4I11/2 and 4I13/2 are 0.61 and 0.82 ms. A diode-end-pumped Er,Pr:GYAP laser is developed in both continuous-wave (CW) and self-Q-switched regimes. The CW output reaches an average power of 508 mW, while two sets of self-Q-switched lasers deliver 356 and 450 mW. The self-Q-switched operations produce pulses with durations of 192.6 ns at 213.5 kHz and 397.4 ns at 106.9 kHz, corresponding to laser wavelengths of 2712.8 and 2797.3 nm, respectively. The saturation power and the modulation depth of Er, Pr:GYAP crystal at 2712 nm are calculated to be 0.34 W and 1.02%. The output beam is near-diffraction-limited, with Mx2/My2 factors of 1.61/1.46. The output laser exhibits linear polarization parallel to the c-axis of Er,Pr:GYAP crystal. These results confirm Er,Pr:GYAP as a highly promising candidate for compact, polarized, self-Q-switched lasers around 3 μm.