Narrow linewidth tunable and dual wavelength compact Alexandrite laser

In this work we present a novel compact Alexandrite laser with continuous wavelength tuning and dual wavelength operation. Wavelength tuning is achieved by tilting a Brewster-cut Alexandrite crystal to change the path length and birefringence in a plane-plane cavity. Fiber-coupled diode pumping provides a small footprint stable system with >1W of output power in TEM00 mode. Results are shown for two laser crystals with the broadest tuning of 746-768nm demonstrated with 15 GHz linewidth. Wavelength tuning at a rate of -0.07nmK(-1) is also demonstrated by varying the crystal temperature. Stable dual wavelength operation with 12-13nm peak-to-peak separation is shown in addition. A theoretical model for wavelength tuning based on the change in geometrical path length and refractive index is found to be in excellent agreement with the experimental results. Power scaling of the system is also investigated with a second compact cavity design. A total tuning range of 754-769nm and dual wavelength operation is demonstrated with a maximum power of 3.2W and beam quality M-2 = 1.8.