Wavelength dependence of repetitive-pulse laser-induced damage threshold in β-BaB_2O_4

Abstract

The dependence on wavelength of repetitive-pulse (10 Hz, 8-10 ns) laser-induced damage on beta barium metaborate (BBO) has been investigated. The thresholds of dielectric breakdown in bulk crystal have been found to be 0.3 GW/cm(2) at 266 nm, 0.9 GW/cm(2) at 355 nm, 2.3 GW/cm(2) at 532 nm, and 4.5 GW/cm(2) at 1064 nm. Results indicate two-photon absorption at 266 and 355 nm, which helps to produce an avalanche effect that causes breakdown at each of the four wavelengths tested. Neither the BBO refractive indices nor the absorption spectrum change until breakdown occurs.

Module-Guided Design Scheme for Deep-Ultraviolet Nonlinear Optical Materials

“…52 For β-BBO, its large birefringence beyond the appropriate region results in a photorefractive phenomenon which reduces the output power of harmonic light. 53 Therefore, finding an optimal composition that satisfies the NLO criteria is still a serious challenge for the discoveries of materials. Tetrahedral groups such as BO 4 or PO 4 are excellent modules because they will effectively avoid layer habits, and their large energy gap is beneficial to deep UV transmission.…”

“…In general, a large birefringence between 0.07 and 0.11 is desired to allow for PM while avoiding spatial walk-off. 53,65 To date, the shortest SHG PM wavelength in phosphates is only 258 nm, observed in KDP, 66 which has a small birefringence of 0.034. Providentially, some centrosymmetric (CS) phosphates with large birefringences were reported, such as LnPO 4 , Ln = (Sc, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu).…”

Growth and characterization of large CLBO crystals

“…The Sasaki group at Osaka University of Japan reported that they obtained a large CLBO crystal with dimensions of 140 mm  110 mm  110 mm in only 21 days, using the [0 1 0] direction crystal seed [2]. For the CLBO crystal the UV laser absorption at 266 nm is very small, and there is almost no photorefractive damage, unlike the BBO crystal [3]. These advantages make CLBO crystal an excellent frequency conversion material to produce UV and deep UV lasers.…”

High-efficency stable 213-nm generation for LASIK application

“…The results show that when pump intensity is too high, the conversion efficiency at fifth harmonic generation drops. This is mainly caused by CLBO's absorption, which increases the nonlinearity at deep UV wavelengths (266nm and 213nm) [16]. …”