Ca4REO(BO3)3 crystals for green and blue microchip laser generation: from crystal growth to laser and nonlinear optical properties

Abstract

We have taken advantage of congruent melting behavior of the nonlinear rare-earth oxoborate Ca4REO(BO3)3 family to perfect a process of collective fabrication of self-frequency doubling microchip laser based on Nd:GdCOB (Ca4Gd1−xNdxO(BO3)3) crystals. The process goes from Czochralski boule to 1 × 3 mm2 chips perfectly oriented (better than 0.1°) to the phase matching direction (θ=90°, φ=46°) in the XY principal plane, with dielectric mirrors directly deposited on both faces of the chips. 20 mW of self-frequency doubling output power at 530 nm was performed under 800 mW of diode laser as incident pump power at 812 nm. In addition, new compositions from the solid solution Ca4Gd1−xYxO(BO3)3 (Gd1−xYxCOB) (x=0.13, 0.16, 0.44) have been grown by the Czochralski pulling method, in order to achieve noncritical phase matching (NCPM) second harmonic generation of 4F3/2 → 4I9/2 Nd3+ doped laser hosts. Three types of laser wavelengths have been chosen: Nd:YAP (YAlO3) at 930 nm, Nd:YAG (Y3Al5O12) at 946 nm, and Nd:ASL (NdySr1−x Lax−yMgx Al12−xO19) at 900 nm. Angular acceptance measurements of these three types of compositions present very large values, compared to pure GdCOB or YCOB oriented in critical phase matching configurations.