Ghosh G
Appl Opt. 1998 Mar 1;37(7):1205-12. doi: 10.1364/ao.37.001205.
Birefringence (B(f)), refractive indices, and their temperature derivatives (dB(f)/dT) determine the temperature characteristics of nonlinear-optical laser devices. The birefringences at different temperatures are analyzed critically by use of a new physically meaningful Sellmeier equation for what is to the author's knowledge the first time the birefringences at different operating temperature from 14 to 500 K and wavelength for ZnGeP(2) nonlinear crystal have been found. This equation is based on the average electronic absorption gap in the UV region and the lattice absorption gap at the IR region. In this model the fitting accuracy is better than the experimental accuracy of ?0.0001 at different temperatures. The refractive indices are estimated at different temperatures from the room-temperature values, the thermo-optic coefficients, and the smoothed values of birefringence. The Sellmeier coefficients for refractive indices that are used to characterize the currently available nonlinear-optical devices satisfactorily are then evaluated. These optical constants are essential in characterizing the parametric short-pulse generation in the mid-IR region.
双折射（B(f)）、折射率及其温度导数（dB(f)/dT）决定了非线性光学激光器件的温度特性。利用一个新的具有物理意义的Sellmeier方程，首次对不同温度下的双折射进行了严格分析，据作者所知，该方程给出了ZnGeP₂非线性晶体在14至500 K不同工作温度和波长下的双折射情况。该方程基于紫外区域的平均电子吸收带隙和红外区域的晶格吸收带隙。在这个模型中，不同温度下的拟合精度优于±0.0001的实验精度。根据室温值、热光系数和平滑后的双折射值估算不同温度下的折射率。然后评估用于令人满意地表征当前可用非线性光学器件的折射率的Sellmeier系数。这些光学常数对于表征中红外区域的参量短脉冲产生至关重要。
