Wavelength switching in 2 µm narrow spectral bandwidth Tm:YAP laser

A birefringent-etalon was used to achieve 2 µm narrow spectral bandwidth laser wavelength switching. The 660 mW narrow spectral bandwidth laser was achieved at the wavelength of 1987.6 nm by adjusting the inclination of the birefringent-etalon in relative to the optical axis of the resonator. The beam quality was M2 = 1.89 and M2 = 1.96 respectively in the x direction and y direction. The wavelength switching was accomplished by rotating the birefringent-etalon along its plane. Four thicknesses of birefringent-etalons were used to achieved switching wavelengths at 1988.7 nm, 1938 nm, 1964.7 nm and 1983 nm with the maximum power of 603 mW, 537 mW, 575 mW and 447 mW, respectively.