级联参量振荡产生太赫兹辐射的理论研究

Theoretical research on terahertz wave generation based on cascaded parametric oscillation

针对光学参量振荡产生太赫兹波转换效率低的缺点,提出了级联参量振荡产生太赫兹波的新机理以提高转换效率.以周期极化铌酸锂晶体为例,对级联参量振荡产生太赫兹波的原理和过程进行了理论研究.分析了抽运光波长、周期极化铌酸锂晶体极化周期和工作温度对产生一阶、二阶闲频光频率的影响.推导了三波共线相互作用条件下太赫兹波的增益特性和吸收特性.计算结果表明,通过级联参量振荡可以有效提高太赫兹波的转换效率,并可以得到宽调谐的太赫兹波输出.基于分析结果,设计了周期极化铌酸锂晶体级联参量振荡产生高效率、宽调谐、窄线宽、连续太赫兹波的实验.

A novel mechanism of cascaded parametric oscillation is proposed in this paper to solve the problem of low-efficiency in terahertz （THz） parametric oscillation. The cascaded parametric oscillation is theoretically analyzed based on PPLN crystal as an example. The tuning characteristics of the THz wave, which are affected by the parameters of pump wavelength, poling period of PPLN and operating temperature, are investigated. The characteristics of THz gain and absorption are deduced in the case of collinear interaction of the three mixing waves. The results indicate that the THz conversion efficiency can be greatly enhanced and the widely tunable THz wave can be realized in cascaded parametric oscillation. The experiment on cascaded parametric oscillation generating high-efficiency, wide-tuning, narrow-linewidth, continuous THz wave is designed based on the analysis above.