Investigation on the thermal characteristic of MgO:PPSLT crystal by transmission spectrum of a swept cavity

Abstract

A method of evaluating the thermal focal length of nonlinear crystal via transmission spectrum of a swept cavity (TSSC) is presented. By recording the resonant point offset of the TSSC, the thermal focal length can be successfully measured. Furtherly, by distinguishing the absorption of ultraviolet (UV) laser and UV laser induced infrared absorption (ULIIRA), it is clear that the ULIIRA is the important factor which induces the thermal lens effect compared to the absorption of UV laser for MgO-doped periodically poled stoichiometric lithium tantalate (MgO:PPSLT) crystal and it becomes serious with the increase of the generated UV laser. The ULIIRA coefficient measurement and thermal focal length evalution of MgO:PPSLT crystal can supply an useful reference for researchers to generate high quality UV laser and squeezed or entangled state of optical field by using MgO:PPSLT crystal. The presented method can also be used to precisely evaluate the thermal focal length of other nonlinear crystals.

High power continuous laser at 461 nm based on a compact and high-efficiency frequency-doubling linear cavity

“…1. Periodically-poled crystals operating at quasi-phase matching condition have been dismissed, despite a promising high conversion efficiency (𝑑 eff ), because of their major limitations at high power induced by the photo-refractive beam distortion, the blue-induced infrared absorption [12], and thermal effects [13]. β-barium borate (BBO) [14] and bismuth triborate (BIBO) [15] crystals were discarded because of their large walk off angle (see Tab.…”

“…Parameters ppsLT [13] ppKTP [18] BiBO [15] BBO [14] The LBO crystal is tightly fixed on the cavity axis; it has a length of 15 mm and a cross section of 3×3 mm 2 . The crystal is cut for normal incidence 𝜃 = 90 𝑜 , 𝜙 = 21 𝑜 at the phase matching at 48 𝑜 𝐶 and has a two layer antireflection coating working at 922 nm (reflectivity R<0.1%) and 461 nm (R<0.3%).…”