Effect of lattice mismatch on the laser-induced damage thresholds of (BiTm)3(GaFe)5O12 thin films

Abstract

Laser-induced damage of magneto-optical (MO) materials in optical isolators remains the crucial factor that limits the application for high-power lasers. In order to explore the application potentiality of Tm3+ and Bi3+ ions-substituted YIG thin films using in high-power laser systems and find parameters that affecting laser-induced damage thresholds (LIDT) of this films. Here, (BiTm)3(GaFe)5O12 single crystal thin films with different growth rate were prepared through liquid-phase epitaxy method. The optical, magneto-optical, LIDT and surface morphologies before and after laser irradiation of the prepared thin films were investigated. Experimental results pointed out that the surface defects generated by lattice mismatch between films and substrates, residual melt in surface defects and difference in intrinsic optical absorption coefficient (α) were the key factors affecting LIDT of (BiTm)3(GaFe)5O12 thin films. Moreover, the maximum Verdet constant (−2.595 × 10−4°/(Oe μm)), the lowest α (66 cm−1@1064 nm) and the highest LIDT (4.28 J/cm2) were obtained of the film with growth rate of 0.84 μm/min, this indicates that the prepared (BiTm)3(GaFe)5O12 thin films are attractive candidate to substitute conventional bulk single crystal MO materials in high-power laser systems.