BaBe₂BO₃F₃: A KBBF-Type Deep-Ultraviolet Nonlinear Optical Material with Reinforced [Be₂BO₃F₂]_∞ Layers and Short Phase-Matching Wavelength

Abstract

D eep-ultraviolet (DUV) coherent light sources (λ < 200 nm), which are always rare resources, have attracted much attention because of the significant role played in semiconductor photolithography, high density storage, laser micromachining, material processing, photochemical synthesis and scientific equipment. 1−4 As is well accepted, the most efficient way to produce practical DUV laser is using solid-state lasers with nonlinear optical (NLO) crystal through cascaded second-harmonic generation (SHG) conversion. Hence, an appropriate DUV NLO crystal that can produce SHG below 200 nm is the key to generating high quality DUV lasers.According to the anionic group theory proposed by Chen, 5−8 a good DUV NLO crystal should possess the following three optical properties: (1) wide transparent range in the UV region with the UV cutoff wavelength far below 200 nm; (2) a moderate birefringence (Δn ∼ 0.08) to ensure the phasematching ability; (3) a sufficient second-order nonlinear coefficient. Specifically, the first two conditions are indispensable for a DUV NLO material. Taking the famous LiB 3 O 5 (LBO) crystal as an example, 9 the transmittance spectrum is wide and the UV absorption edge is down to about 155 nm.

Neue Kandidaten für die nichtlineare Optik im Tief‐UV‐Bereich

“…Die meisten dieser Materialien sind bis in den tiefen UV‐Spektralbereich transparent, weisen beachtliche SHG‐Antworten und einen günstigen Wachstumshabitus auf, jedoch erreichen noch immer nur wenige tatsächlich erhaltene Kristalle oder vorhergesagte Strukturen PM‐Verhalten im tiefen UV‐Spektralbereich unter 200 nm. Soweit uns bekannt (siehe Tabelle 1, Tabelle 2 und Abbildung 4), ist – außer KBBF, RBBF und SBBO– bisher für nur wenige Kristalle, darunter experimentell erhaltenes BaBe 2 BO 3 F 3 (BBBF), [43a] NH 4 Be 2 BO 3 F 2 (ABBF), [44] Be 2 BO 3 F ( C 2), [45] Be 2 BO 3 F ( R 32), [44] Cs 2 Al 2 (B 3 O 6 ) 2 O [43b] und CsAlB 3 O 6 F [43c] sowie theoretisch entworfenes LiBe 2 BO 3 F 2 ( R 32), [46] NaBe 2 BO 3 F 2 ( R 32), [46] Be 2 BO 3 F ( P 2 c ), [47] NaBeBO 3 ( P c ) [48] und NaBeBO 3 ( P ), [48] zu erwarten, dass sie Tief‐UV‐Laserstrahlung durch das direkte SHG‐Verfahren abgeben. Diese Kandidaten haben zahlreiche Strukturmerkmale gemeinsam:…”

Borate-Based Ultraviolet and Deep-Ultraviolet Nonlinear Optical Crystals

“…Much effort has been devoted to overcome the layering habit of KBBF family crystals. In 2016, Guo et al proposed the strategy to improve the growth habit by enhancing electrostatic interaction, and successfully synthesized BaBe 2 BO 3 F 3 (BBBF) [30]. BBBF crystallizes in hexagonal space group of P6 3 .…”

深紫外氟化硼酸盐双折射率和折射率色散的性能 增益研究

“…By introducing fluorine into borates, one can obtain two kinds of compounds: borate fluorides with the fluorine connecting the metal cations and fluorooxoborates with the fluorine also connecting the boron atom. The most typical borate fluorides are KBBF [10,24], RbBe 2 BO 3 F 2 (RBBF) [25], BaBe 2 BO 3 F 3 [26], BaAlBO 3 F [27] [34][35][36][37]. Among them, AB 4 O 6 F (A = NH 4 , Cs) has the ability to generate DUV coherent light [34,35].…”