一种新的有机非线性光学晶体——L-精氨酸磷酸盐

近年来,在探索新的有机非线性光学晶体的工作中,对含有给电子或受电子基团的芳香族化合物已有广泛深入的研究,并已研制出像2,4-二硝基苯丙氨酸甲酯(MAP)等具有较大倍频系数的新的非线性光学晶体。但是,由于强的共轭效应使它们大π键各能级间的距离接近而使此类晶体无法应用于紫外区。

A new phase matchable nonlinear optic crystal L-abginine phosphate monohydrate

Insearch of new organic nonlinear optic crystals, aromatic compounds with donor and acceptor substituents are extensively studied. Some new crystals with large nonlinear coefficient have been reported. This kind of crystals is usually not useful in ultraviolet regoion, because the distance between energy levels in conjugated π bonds gets smaller due to the strong conjugation effect. In exploring new organic nonlinear optic crystals used in ultraviolet region, we have discovered a new phase matchable nonlinear optic organic crystal -- L-arginine phosphate monchydrate. Of the size 13X35X35mm^3 LAP single crystals with good optical quality have been grown by the cooling and evaporating methods. LAP crystal belongs to monoclinic system; its space group is P21. It shows the following properties: (1) transparency range over 10% extends from 230nm to 1940nm; over 50% extends from 240nm to 1500nm; (2) when basic wave is 1064nm and harmonic wave is 532nm, the calculated phase matching curved surface belongs to Hobden's ninth type; (3) SHG intensity of LAP crystal in phase matching direction (w=57, t=-13, phase matching type II) is 3.5 times greater than that of KDP crystal (w=59, Ps=0, type II). It is worth to note that this direction of LAP crystal will not be one of its maximum effective nonlinear coefficient; (4) when basic waves are 1064nm and 532nm, the sum-frequency effect has been observed; (5) the optical damage threshold is higher than 1 GW/cm^2.s at 1064nm; (6) the stability towards atmospheric moisture is excellent. As a result, LAP crystal is a promising nonlinear optic crystal.