New method to determine the refractive index and the absorption coefficient of organic nonlinear crystals in the ultra-wideband THz region.
New method to determine the refractive index and the absorption coefficient of organic nonlinear crystals in the ultra-wideband THz region.
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DOI：
10.1364/oe.18.017306
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发表时间：
2010-08
期刊：
影响因子：
3.8
通讯作者：
S. Ohno;K. Miyamoto;H. Minamide;Hiromasa Ito
中科院分区：
文献类型：
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作者：
S. Ohno;K. Miyamoto;H. Minamide;Hiromasa Ito
介绍了一种同时测量超宽带太赫兹（THz）区域非线性光学晶体折射率和吸收系数的方法。这种方法是基于分析的共线差频产生（DFG）过程中使用的可调谐，双波长，光学参量振荡器。利用差频光栅测量了有机非线性晶体DAST在2.5- 26.2THz波段的折射率和吸收系数。所得的折射率在x方向上约为2.3，而吸收光谱与FT-IR测量结果非常一致。利用测量的太赫兹波段折射率谱对DAST-DFG太赫兹波源的输出进行了相位匹配优化，使其输出功率提高了9倍。
A method for simultaneously measuring the refractive index and absorption coefficient of nonlinear optical crystals in the ultra-wideband terahertz (THz) region is described. This method is based on the analysis of a collinear difference frequency generation (DFG) process using a tunable, dual-wavelength, optical parametric oscillator. The refractive index and the absorption coefficient in the organic nonlinear crystal DAST were experimentally determined in the frequency range 2.5-26.2 THz by measuring the THz-wave output using DFG. The resultant refractive index in the x-direction was approximately 2.3, while the absorption spectrum was in good agreement with FT-IR measurements. The output of the DAST-DFG THz-wave source was optimized to the phase-matching condition using the measured refractive index spectrum in THz region, which resulted in an improvement in the output power of up to a factor of nine.