Off-axis pumped broad 1.5–1.6 μm wavelength-tunable Er:Yb:YAl3(BO3)4 vortex laser

Broad 1.5–1.6 μm wavelength-tunable solid-state vortex laser has important application in advancing the high-capacity and low-loss optical communication. However, high-order and broad wavelength-tunable 1.5–1.6 μm vortex laser is difficult to be realized in the existing Er 3+ -doped laser materials up to now. In this work, 1.5–1.6 μm vortex laser with high-order Laguerre–Gaussian (LG) mode and broadband tunability was firstly demonstrated in an Er 3+ /Yb 3+ co-doped material end-pumped by a 976 nm diode laser. Based on an off-axis pumping scheme combined with an astigmatic mode conversion, 1602 nm vortex lasers with LG 0, m ( m = ±1, ±2, ±3, ±4) modes were successfully realized in an Er:Yb:YAl 3 (BO 3 ) 4 crystal. The effect of output coupler transmission on the wavelength tunability of the vortex lasers with different LG 0, m modes was also investigated, when a SiO 2 birefringent filter was inserted as a tunable element. The maximum continuously tunable bandwidths for the TEM 0,0 , LG 0,±1 , and LG 0,±2 modes were 90 nm (1518–1608 nm), 46 nm (1516–1562 nm), and 15 nm (1542–1557 nm), respectively. The highest output powers for the LG 0,±1 and LG 0,±2 modes were about 173 mW at 1543 nm and 72 mW at 1551 nm, respectively. The mode order and tunable bandwidth realized in this work are larger than those reported previously in the 1.5–1.6 μm vortex lasers, which are favorable for effectively improving the channel capacity and spectral efficiency of optical communication system.