Crystal Growth and Physical Properties of the Nonlinear Optical Crystal KLi(HC₃N₃O₃)·2H₂O

Abstract

A hydro-isocyanurate nonlinear optical (NLO) crystal, KLi(HC 3 N 3 O 3 )•2H 2 O (KLHCY), with dimensions of 60 × 55 × 30 mm 3 , has been successfully developed by means of a water solution method, whose quality is evidenced through the rocking curve measurement. Its thermophysical properties are explored thoroughly, evidencing the possibility of potential laser applications. Meanwhile, refractive index measurements are carried out by the auto-collimation method and fitted well according to Sellmeier equations, deriving moderate birefringence within 266− 1064 nm. Based on the progressive works, phase-matching (PM) wavelength ranges for KLHCY are revised, where the type Ι and type ΙΙ PM fundamental wavelengths cover 482−5178 and 524− 3174 nm, respectively. Hence, the 266 nm light generation can be acquired by type Ι PM conditions, in which PM angles are elaborately derived to (φ = 50°, θ = 90°) and (φ = 0°, θ = 38.5°). Furthermore, the NLO coefficients of KLHCY are perfected through the Maker fringe method, determined as |d 31 | = 1.97 pm V −1 , |d 32 | = 0.20 pm V −1 , and |d 33 | = 2.47 pm V −1 , showing leading values over the known fourth harmonic generation (FHG) NLO crystals. Consequently, this work concentrates on the further investigation for the physical properties of the KLHCY crystal and paths an expansive avenue for the growth and prosperous applications of the KLHCY crystal in promising realms.

A promising ultraviolet nonlinear optical crystal: Rb3Ba3Li2Al4B6O20F—crystal growth, physical properties, and 266 nm laser generation

“…This is beneficial to improve the beam quality of output light and SHG conversion efficiency. 11,33,34…”

“…Thermal expansion, specific heat, thermal diffusivity, and thermal conductivity are also significant parameters used to evaluate crystal growth and application in devices. 11,37 For example, a small thermal expansion will avoid cracking of crystal during growth and application, and a large specific heat is favorable for high LDT of crystal. The thermal diffusivity and thermal conductivity are close to the output beam quality and service life of NLO crystal.…”

“…9,10 Remarkably, extremely few NLO crystals are available in the UV region, especially the fourth harmonic generation (FHG, 266 nm) output of a fundamental wavelength (1064 nm). 11,12 Currently, only two crystals β-BaB 2 O 4 (β-BBO) 13 and CsLiB 6 O 10 (CLBO) 14 are commercially available. However, some intrinsic demerits restrict their further applications, i.e.…”

K3C6N7O3·2H2O: A Multifunctional Nonlinear Optical Cyamelurate Crystal with Colossal π-Conjugated Orbitals

“…12−14 Especially since 2017, our group first studied the microscopic properties of large π-conjugated cyanurate (C 3 N 3 O 3 ) 3− , 15 thus greatly triggering the rapid developments in this field. 16 A succession of new crystals, including K 6 Cd 3 (C 3 N 3 O 3 ) 4 , 17 KLi(HC 3 N 3 O 3 )•2H 2 O, 18,19 20 and LiCl•(H 3 C 3 N 3 O 3 ), 21 were discovered and grown. In addition, some new π-conjugated groups were immediately explored by many research groups, 22−30 ] six-member ring.…”

“…Among them, π-conjugated groups may be the most important and successful, owing to their large optical anisotropy and remarkable microscopic second-order susceptibility, which promotes the discovery of some commercialized crystals, such as KBe 2 BO 3 F 2 (KBBF) with a (BO 3 ) 3– group, β-BaB 2 O 4 (BBO) with a (B 3 O 6 ) 3– group, and LiB 3 O 5 with a (BO 3 ) 3– group. − Especially since 2017, our group first studied the microscopic properties of large π-conjugated cyanurate (C 3 N 3 O 3 ) 3– , thus greatly triggering the rapid developments in this field . A succession of new crystals, including K 6 Cd 3 (C 3 N 3 O 3 ) 4 , KLi­(HC 3 N 3 O 3 )·2H 2 O, , Cs 3 Na­(H 2 C 3 N 3 O 3 ) 4 ·3H 2 O, and LiCl·(H 3 C 3 N 3 O 3 ), were discovered and grown. In addition, some new π-conjugated groups were immediately explored by many research groups, − e.g., (C 3 H 7 N 6 ) + , (C 5 H 6 ON) + , (C 4 H 6 N 3 ) + , [C­(NH 2 ) 3 ] + , (HC 4 O 4 ) − , (C 6 N 9 ) 3– , (HC 3 N 3 S 3 ) 2– , and (H 2 C 4 N 2 O 3 ) 2– .…”