Switchable Multi-Wavelength Nd:Lu2SiO5 Laser Based on a Wedge Birefringent Filter for the 4F3/2 → 4I13/2 Transition

We report, for the first time, a continuous-wave (CW) switchable multi-wavelength Nd:Lu2SiO5 (Nd:LSO) laser using two wedge birefringent filters (WBFs) operating on the 4F3/2 → 4I13/2 transition. The threshold equivalence condition was calculated via the two intracavity WBFs to achieve the simultaneous multiple-wavelength operation. Three dual-wavelength pairs (1332/1344 nm, 1344/1359 nm, and 1359/1363 nm), two triple-wavelength combinations (1332/1344/1359 nm and 1344/1359/1363 nm), and a four-wavelength set (1332/1344/1359/1363 nm) were further experimentally demonstrated. These wavelength combinations are mutually switchable via tuning of the WBF. Under an incident pump power of 20 W at 808 nm, the total output powers for the dual-wavelength pairs (1332/1344 nm, 1344/1359 nm, and 1359/1363 nm) were measured to be 1.55 W, 2.17 W, and 3.40 W, respectively. The triple-wavelength outputs at 1332/1344/1359 nm and 1344/1359/1363 nm delivered 1.57 W and 1.91 W, respectively. The four-wavelength emission at 1332/1344/1359/1363 nm reached 913 mW.