铌酸锂电光调Q晶体漏光现象的研究

Study on Light Leakage Phenomenon of Lithium Niobate Electro-optic Q-switching Crystals

针对铌酸锂(LN)电光调Q开关性能一致性差、退压式调Q时无法完全关断光路的问题进行了系统研究。在闪光灯泵浦Nd∶YAG激光系统中,对多块LN电光调Q开关的退压式电光调Q性能进行了对比测试,并从电光调Q理论出发,分析了光路无法关断的可能原因。在此基础上,利用X射线定向仪、锥光干涉法对各晶体的轴向偏差、光学均匀性进行了表征,首次发现了LN晶体的电光不均匀性,即感应主轴偏离理论上的45°方向、通光截面各处感应双折射不一致。通过对比实验,证实了电光不均匀性是造成光路无法关断、不同开关性能差异较大的主要原因。

A systemic research were carried out on the problem that the lithium niobate(LN)electro-optic(EO)Q-switches have poor consistence and can not completely hold-off in pulse-off Q-switching mode.The pulse-off EO Q-switching performances of several LN Q-switches were investigated in a flash-lamp pumped Nd∶YAG laser.The possible causes for the light leakage were analyzed according to EO Q-switching theory.On these basis,the axial deviation and optical inhomogeneity were characterized by a X-ray diffraction goniometer and the conoscopic interference method.The EO inhomogeneity of LN crystals was first found,the direction of main induction axis deviated from the theoretical 45°and the induced birefringence was inconsistent throughout the clear aperture.Through contrast experiments,the EO inhomogeneity is verified to be the main reason to cause the light leakage and poor consistence.