Deep-Ultraviolet Nonlinear Optical Crystals: Ba₃P₃O₁₀X (X = Cl, Br)

Abstract

Deep-ultraviolet nonlinear optical (deep-UV NLO) crystals are of worldwide interest for the generation of coherent light with wavelength below 200 nm by the direct second-harmonic generation (SHG) output from solid-state lasers. The unprecedented deep-UV NLO phosphates representing their own structure types, Ba3P3O10Cl (BPOC), Ba3P3O10Br (BPOB), have been discovered, which display moderate powder SHG intensities in type I phase matchable behaviors with a short UV cutoff edge of 180 nm (measured by a single crystal, one of the shortest values among phosphates to date). Insightfully, the geometry and polarization of the C1-P3O10(5-) building unit are affected by the crystal packing. DFT calculations and cutoff energy dependent SHG coefficient analyses reveal that the SHG origin is from the cooperation of asymmetric C1-P3O10(5-) anion, Ba(2+) cation, and Cl(-)/Br(-) anion.

Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal

“…It can be seen that the SHG efficiency of KLa(PO 3 ) 4 is about 0.7 times that of KDP. This value is comparable to most of the deep-UV NLO phosphate crystals, such as Rb 2 Ba 3 (P 2 O 7 ) 2 (0.3 × KDP), CsLa(PO 3 ) 4 (0.5 × KDP), Ba 3 P 3 O 10 Cl (0.6 × KDP), Ba 5 P 6 O 10 (0.8 × KDP), and RbBa 2 (PO 3 ) 5 (1.4 × KDP)17181922. Moreover, the results indicate that KLa(PO 3 ) 4 is a type I phase-matchable material in visible region according to the rule proposed by the Kurtz and Perry method35.…”

“…This remarkable deep-UV absorption edge not only is much shorter than those of well-known KTiOPO 4 and KDP crystals34, but also is shorter than those of the phosphate NLO crystals reported recently, such as BaP 3 O 10 Cl (180 nm)17, RbBa 2 (PO 3 ) 5 (163 nm)18, Ba 5 P 6 O 20 (167 nm)19, and CsLa(PO 3 ) 4 (167 nm)22. It is also comparable to those of beryllium borates, such as KBBF (155 nm)5, NaSr 3 Be 3 B 3 O 9 F 4 (170 nm)9, and LiNa 5 Be 12 B 12 O 33 (169 nm)11, and those of beryllium-free borates, such as BaAlBO 3 F 2 (165 nm)34 and Ba 4 B 11 O 20 F (<175 nm, from powder diffuse reflectance spectrum)13.…”

“…Recently, several acentric compounds, including Na 3 Lu(CO 3 ) 2 F 2 , Ba 3 P 3 O 10 Cl, RbBa 2 (PO 3 ) 5 , Ba 5 P 6 O 10 , Sr 2 (OH) 3 NO 3 , and RbMgCO 3 F, have been discovered, which have rather wide energy gaps161718192021. These discoveries suggest that deep-UV NLO compound should not be confined to borates.…”

Three Alkali Metal Lead Orthophosphates – Syntheses, Crystal Structures and Properties of APbPO4 (A = K, Rb, Cs)

“…For example, KH 2 PO 4 (KDP) and KTiOPO 4 (KTP) have been widely used as nonlinear optical (NLO) devices 7. Ba 3 P 3 O 10 Cl/Br,8 RbBa 2 (PO 3 ) 5 , and Rb 2 Ba 3 (P 2 O 7 ) 2 9 are also potential deep‐UV NLO materials for their short deep‐UV absorption edge and moderate NLO activity. Some calcium phosphates have been used in bone reconstructive surgery because of their very good biocompatibility and bone integration qualities 10.…”

Recent advances on second-order NLO materials based on metal iodates

“…In the meantime several new metal phosphates with good SHG properties have been also discovered [40,41]. The efforts to replace BO 3 groups with isoelectronic anions such as carbonate and nitrate groups have afforded a variety of new NLO crystals based on carbonates [42,43] and nitrates [44][45][46].…”