Until now, KBe2BO3F2 (KBBF) is still the only practically usable deep ultraviolet (DUV) nonlinear optical (NLO) crystal that can generate DUV coherent light by the direct second harmonic generation. However, the commercial production and applications are seriously hindered by its layering habit. For decades, exploring new DUV NLO crystal remains an urgent issue.
Recently, Prof. YE Ning’s group at Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences successfully designed and synthesized two new excellent DUV NLO crystals NH4Be2BO3F2 (ABBF) and γ-Be2BO3F (γ-BBF) based on the structure of KBBF. The work was published in Angew. Chem. Int. Ed..
The two crystals all perfectly inherited the favorable structure merits of KBBF. Besides, for ABBF the N-H...F hydrogen bonds effectively overcome the layering habit.
As to γ-BBF, the in-site excision of A-site atoms (NH4+ or K+) makes the adjacent layers bridged directly by Be-F ionic bond, showing strong interlayer bonding.
The UV cut-off edges, birefringences and second-harmonic generation effects of ABBF and γ-BBF are very close to or even better than KBBF, making their shortest type I phase-matching (PM) second-harmonic wavelength (λPM) down to 173.9 nm and 146 nm, respectively.
Their excellent DUV laser output potential means this work represents a breakthrough in the field of deep ultraviolet nonlinear optical crystal.
Crystal structures of KBBF, ABBF and γ-BBF(Image by Prof. YE’s group)
Contact:
Prof. YE Ning
Fujian Institute of Research on the Structure of Matter
Chinese Academy of Sciences
Email: nye@fjirsm.ac.cn
