摘要:
基于在539.75nm,632.8nm,1079.5nm,1341.4nm波长上和288K,338K,383K,423K温度条件下,对掺5mol%MgO和0.2mol%Ti的LiNbO3晶体的主折射率的精密测量,根据对LiNbO3晶体适用的修正的Sellmeier's方程,以解出参数Ci表达式的方法,求出上述温度时Sell-meier's方程的参数Ai,Bi,Ci,Di,以最小二乘法精确地拟合上述参数对温度T的线性关系,进而推导出这种晶体的折射率温度系数的表示式。利用此表示式可以计算波长在539.75nm～1341.4nm区间附近,温度在288K～423K范围左右Ti:Mg:LiNbO3晶体的折射率温度系数。为检验该折射率温度系数表示式的实用性,利用此表示式计算1079.5nm为基波的该晶体的二倍频非临界相位匹配温度,与实验值之差在1K以内,从而证明这个折射率温度系数表示式对于采用Ti:Mg:LiNbO3,晶体设计非线性光学器件是适用的。
Abstract:
The principal refractive indices and the thermal coefficients of LiNbO3 crystal doped with 5mol%MgO and 0.2mol%Ti were accurately measured at the wavelengths of 539.75nm, 632.8nm,1079.5nm and 1341.4nm,and at the tempera-tures of 288K,338K and 423K,It is straightforward to use Sellmeier's equation,modified to suite to LiNbO3 crystal,to solve the parameters Ai, Bi, Ci, and Di of Sell-meier's questions at aforesaid temperatures in an analogy manner of solving the expres-sion of parameter Ci.Then the relationship of parameters Ai,Bi,Ci and Di with tem-peratures T is obtained in terms of least-squares fit.Then the expression of thermal re-fractive index coefficients of LiNbO3 crystal can be inferred.With the expression,the thermal refractive index coefficients of Ti:Mg:LiNbO3 crystal in the wavelength and temperature ranges of 539.75nm～1341.4nm and 288K～423K can be calculated.To examine the practicability of the expression of thermal refractive index coefficients,the noncritical phase matching temperature for 1079.5nm SHG has been calculated,the differences between the calculated and experimented value is less than 1K.Therefore,the expressions are useful for design of nonlinear optical devices of using Ti:Mg:LiNbO3 crystal.
下载: