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产生太赫兹波辐射的方法可分为电子学和光子学两大类。在光子学领域,非线性光学差频方法是获取高功率、低成本、便携式、室温运转太赫兹波的主要方法之一。实验研究了激光二极管(LD)端面抽运Nd∶YAG1319nm/1338nm双波长准连续线偏振运转激光器,理论计算了输出双波长在非线性晶体DAST(4-N,N-di methylamino-4′-N′-methyl-stilbazolium tosylate)中差频产生太赫兹辐射的平均功率。在重复频率50kHz时,双波长激光平均输出功率达到2.22W,斜率效率12.72%,线偏振度0.983,脉冲宽度71.91ns。M2因子仅为1.165,不稳定性小于0.487%。根据非线性差频理论,计算出可在1mm厚DAST晶体中获得4.71mW的3.23THz高相干性太赫兹波辐射。这两条非常接近的谱线为进一步通过非线性光学差频方法获得高相干性太赫兹波提供了理论基础。
Terahertz radiation generated by the method can be divided into two major categories of electronics and photonics. In the field of photonics, the nonlinear optical difference frequency method is one of the main methods for obtaining high power, low cost, portable and terahertz operation at room temperature. The experiment of laser diode (LD) end-pumped Nd:YAG1319nm / 1338nm dual-wavelength quasi-continuous linearly polarized operating laser was studied experimentally. The output wavelength of the output dual-wavelength laser in DAST (4-N, N-di methylamino-4’-N ’-methyl-stilbazolium tosylate) The average power of terahertz radiation generated by the difference frequency. At 50kHz repetition rate, the average output power of dual-wavelength laser reaches 2.22W, the slope efficiency is 12.72%, the linear polarization is 0.983 and the pulse width is 71.91ns. The M2 factor is only 1.165 and the instability is less than 0.487%. According to the nonlinear difference frequency theory, a 3.23 THz high coherency terahertz wave radiation was obtained that achieves 4.71 mW in a 1 mm thick DAST crystal. These two very close spectral lines provide the theoretical basis for further obtaining the highly coherent terahertz wave by the method of nonlinear optical difference frequency.