Investigation on nonlinear characteristic, weak absorption and damage of Tm doped YCOB

Thulium-doped YCa4O(BO3)(3) (Tm:YCOB) is a novel nonlinear optical crystal, which has potential applications in quasi-parametric chirped pulse amplification (QPCPA). However, the nonlinear characteristic and damage behavior of Tm:YCOB crystal was seldom investigated. Here, Raman spectra was used to analyze the functional groups that cause the nonlinear characteristics of Tm0.1Y0.9COB. The nonlinear refraction and weak absorption of Tm0.1Y0.9COB crystals were studied from the aspects of electronic effect and thermal effect. The nonlinear refractive indices of the crystal in the three directions are 5.61-6.01 x 10(-7) cm(2)/GW (@ 1064 nm), which is less than that of YCOB crystal. The weak absorption values at 1064 nm of the crystal were measured to be similar to 8 x 104 ppm/cm (X), similar to 3 x 10(4) ppm/cm (Y) and similar to 5 x 10(4) ppm/cm (Z), respectively. We studied the relationship between the differences of weak absorption values in three optical axis and the crystal structure. The damage threshold of Tm0.1Y0.9COB at 1064 nm was measured to be 5.31 GW/cm(2), which was twice that of YCOB. The reason for the damage threshold of Tm0.1Y0.9COB higher than that of YCOB was also discussed.

Automated summary

This article investigates the nonlinear characteristics and damage behavior of Tm:YCOB crystal and compares it with YCOB crystal. Raman spectra were used to analyze the functional groups causing the nonlinear characteristics of Tm0.1Y0.9COB. The study examines the nonlinear refraction and weak absorption of Tm0.1Y0.9COB crystals from the perspectives of electronic and thermal effects. The weak absorption values and differences in absorption values in three optical axes were measured and analyzed. Finally, the higher damage threshold of Tm0.1Y0.9COB compared to YCOB was discussed.