【摘要】 理论分析了双光子和三光子吸收对非线性材料差频产生太赫兹(THz)波的影响,在不同抽运功率下,计算了相位失配情况下晶体的最佳作用长度和THz的最大量子转化效率,并将其与相位匹配情况进行对比。研究结果表明,抽运功率不太高时,多光子吸收对差频产生THz波影响不大;随着抽运功率的提高,多光子吸收的影响变得显著;抽运功率较高时,相位匹配与相位失配情况下,双光子和三光子吸收效应都增加了晶体的最佳作用长度,降低了THz的最大转化效率。研究了降低多光子吸收的方法。更多还原

【Abstract】 A general analysis of the influence of two-photon or three-photon absorption on terahertz(THz) generation via optical- difference frequency generation from the nonlinear optical material is presented. We calculate the best length of crystal and the corresponding THz quantum conversion efficiency for different values of the pump peak power under phase-mismatched condition and compare the results with that in phasematched condition. From the results we know that multi- photon absorption influence difference frequency generation slightly at low pump power and the impact will be strong with the increase of pump power. Because of the effect of two-photon or three-photon absorption, difference frequency generation at high pump power requires longer crystal to achieve the maximum photon conversion efficiency for both phase- matched and phase-mismatched situations. The maximum photon conversion decreases when pump power increases.We also present approaches to reduce this adverse effect.更多还原