Deep uv (lambda < 200 nm) nonlinear optical (NLO) crystal is an essential crystal material for all solid-state deep uv lasers.At present, only Chinese scientist Chen chuangtian and other inventions KBe2BO3F2 (KBBF) crystal can output deep uv laser in real time.KBBF crystal has been used in China to develop a series of unique and related deep uv solid laser technology and laser source equipment, and has obtained important applications in many frontier scientific research.
However, it is difficult to overcome this defect in KBBF crystal, such as the highly toxic and serious layer growth habit of the raw beryllium element, which greatly restricts its commercial production and application process.Therefore, all the research institutes around the world are actively exploring the development of a new generation of deep ultraviolet NLO crystal materials.
The key scientific problem of exploring new and deep ultraviolet NLO crystals is that the new material needs to meet the contradictory performance indexes of "deep uv transmission - large - frequency effect - large double refraction".
Technical institute of physics and chemistry of the Chinese academy of sciences, xinjiang special environment function material and devices of the Chinese academy of sciences key laboratory of Pan Shilie group through the system summarizes recent systems containing halogen borate (Coord. Chem. Rev. 2016, 323, 15), the simulation method based on the material presents a introducing 4 - functional groups (BO3F) borate framework design strategy;Based on this strategy, a series of potential lithium perfluorocarbons (Angew. Chem.int.ed., 56, 3916) were successfully screened.
On the basis of this work, the researchers used the structural characteristics of KBBF crystal to further adopt NH4 + substitute K +, (BO3F) 4 - substitute (BeO3F) 5 - and successfully designed the synthesis of NH4B4O6F (ABF) crystal.Experiments show that the material has a very short ultraviolet end edge (156 nm), a larger frequency multiplication coefficient (3 x KDP), moderate birefringence can satisfy the deep ultraviolet phase matching (match the shortest wavelength of 158 nm).
At the same time, compared with the KBBF, the crystal structure of ABF is more compact and the interlayer work is enhanced significantly, thus eliminating the layered growth habit and obtaining the crystal of the centimeter level.In addition, the materials of this material contain no highly toxic beryllium elements, and the frequency multiplier effect is 2.5 times of KBBF, which can be used for the higher conversion efficiency of the deep uv laser light source.ABF has excellent comprehensive performance and is expected to be the next generation of deep uv NLO crystal.