High energy, high repetition rate, second harmonic generation in large aperture DKDP, YCOB, and LBO crystals

Abstract

We report on type-I phase-matched second harmonic generation (SHG) in three nonlinear crystals: DKDP (98% deuteration), YCOB (XZ plane), and LBO (XY plane), of 8 J, 10 Hz cryogenic gas cooled Yb:YAG laser operating at 1029.5 nm. DKDP exhibited an efficiency of 45% at a peak fundamental intensity of 0.24 GW/cm² for 10 Hz operation at 10 ns. At the same intensity and repetition rate, YCOB and LBO showed 50% and 65% conversion efficiencies, respectively. Significant improvement in conversion efficiency, to a maximum of 82%, was demonstrated in LBO at 0.7 GW/cm² and 10 Hz, generating output energy of 5.6 J at 514.75 nm, without damage or degradation. However, no improvement in conversion efficiency was recorded for YCOB at this increased intensity. Additionally, we present theoretically calculated temperature maps for both 10 J and 100 J operation at 10 Hz, and discuss the suitability of these three crystals for frequency conversion of a 100 J, 10 Hz diode pumped solid state laser (DPSSL).

Thermal-stress-induced birefringence management of complex laser systems by means of polarimetry

“…This polarization change originates from stress induced birefringence caused by heat load occurring dominantly in the amplifier. Such polarization changes reduce energy available to polarization sensitive experiments such as harmonic conversion 1 or optical parametric amplification 2 – 4 . Losses in such cases can be as high as 50%.…”

Growth and characterization of a highly homogeneous Er0.12Y0.88COB crystal for nonlinear optical applications

“…Therefore, novel nonlinear optical crystals need to be grown to verify the QPCPA technology at different wavelengths. To date, the commonly used NLO crystals include β-BaB 2 O 4 (BBO), 13 LiB 3 O 5 (LBO), 14 KH 2 PO 4 (KDP) 14 and YCa 4 OIJBO 3 ) 3 (YCOB). 14,15 Among these crystals, BBO crystals have the highest effective nonlinear coefficient (d eff ), 16 KDP crystals have the largest aperture (up to 600 mm), 17 and LBO crystals have the maximum acceptance angle.…”

“…To date, the commonly used NLO crystals include β-BaB 2 O 4 (BBO), 13 LiB 3 O 5 (LBO), 14 KH 2 PO 4 (KDP) 14 and YCa 4 OIJBO 3 ) 3 (YCOB). 14,15 Among these crystals, BBO crystals have the highest effective nonlinear coefficient (d eff ), 16 KDP crystals have the largest aperture (up to 600 mm), 17 and LBO crystals have the maximum acceptance angle. 18 YCOB crystals have excellent comprehensive properties, such as moderate d eff and aperture, stable physicochemical properties, and good thermal properties.…”

Investigation on the Structure of a LiB3O5–Li2Mo3O10 High-Temperature Solution for Understanding the Li2Mo3O10 Flux Behavior

“…The lithium triborate (LiB 3 O 5 ) crystal is the best selection for generating the second and third harmonics of the Nd:YAG laser because of its appealing properties such as relatively large nonlinear optical coefficients, a wide transparency range, a high damage threshold, a large acceptance angle, good chemical stability, and good mechanical properties. , Recently, particular attention has been paid to the crystal application in superintense and ultrafast laser systems. − For example, by using a 100 mm × 100 mm × 17 mm LiB 3 O 5 crystal, Liang and co-workers constructed a high-energy and high-conversion-efficiency laser system that achieved a peak power of 1.02 PW (1 PW = 10 15 W) with a pulse duration of 32 fs (1 fs =10 –15 s) . Such works are expected to open new prospects for studying the physics of intense fields and nonlinear quantum electrodynamics and for developing new technological applications, including laser particle acceleration, laser-assisted thermonuclear fusion, and new laser medical therapies. , The superintense and ultrafast laser systems demand wide-aperture and high-quality LiB 3 O 5 crystals, stimulating us to find better techniques to grow LiB 3 O 5 crystals.…”

“…6 Such works are expected to open new prospects for studying the physics of intense fields and nonlinear quantum electrodynamics and for developing new technological applications, including laser particle acceleration, laser-assisted thermonuclear fusion, and new laser medical therapies. 7,8 The super-intense and ultrafast laser systems demand wide-aperture and high-quality LiB 3 O 5 crystals, stimulating us to find better techniques to grow LiB 3 O 5 crystals.…”