Non-critical phase-matched second-harmonic-generation and third-harmonic-generation of 1053 nm lasers in Gd_xY_1-xCOB crystal

To achieve the non-critical phase-matching (NCPM) frequency conversions of an Nd:glass laser (1053 nm), a series of GdxY1-xCOB (x = 0.186, 0.156, 0.132, and 0.127) crystals have been grown by the Czochralski pulling method. Using an optical parametric oscillator laser, the room temperature NCPM second-harmonic-generation (SHG) and third-harmonic-generation (THG) wavelengths along the y-axis were determined for different GdxY1-xCOB crystals. By controlling the temperature of the Gd0.132Y0.868COB crystal, the NCPM SHG and THG of the 1053 nm laser were realized at 28 °C and 55 °C, respectively. Correspondingly, the angular acceptance, temperature acceptance, and optical conversion efficiencies were researched with a 1053 nm Nd:YLF laser as the fundamental light source. The gray-track generated during large energy THG is expected to be removed effectively by elevating the crystal temperature.