Saito Kyosuke, Tanabe Tadao, Oyama Yutaka
Appl Opt. 2015 Apr 1;54(10):2769-75. doi: 10.1364/AO.54.002769.
In this paper, we describe our theoretical investigation and calculations for a terahertz (THz)-wave profile generated by difference frequency mixing (DFM) of focused, cylindrically symmetric, and polarized optical vector beams. Using vector diffraction theory, the second-order nonlinear polarization was estimated from the electric field components of the optical pump beams penetrating uniaxial, birefringent nonlinear optics (NLO) crystals, GaSe and CdSe. The approximate beam patterns of the THz waves were simulated using DFM formulation. The intensity patterns of the THz waves for GaSe and CdSe showed sixfold symmetry and cylindrical symmetry, respectively, based on the nonlinear susceptibility tensor of the crystals. As the phase-matching angle θ(PM) was constant with respect to the c axis of the NLO crystals, an annular vector beam with a narrow width was expected.
在本文中，我们描述了对由聚焦、圆柱对称且偏振的光学矢量光束的差频混频（DFM）产生的太赫兹（THz）波轮廓的理论研究和计算。利用矢量衍射理论，从穿透单轴双折射非线性光学（NLO）晶体GaSe和CdSe的光泵浦光束的电场分量估算二阶非线性极化。使用DFM公式模拟了太赫兹波的近似光束图案。基于晶体的非线性极化率张量，GaSe和CdSe的太赫兹波强度图案分别呈现六重对称性和圆柱对称性。由于相位匹配角θ(PM)相对于NLO晶体的c轴是恒定的，预计会产生具有窄宽度的环形矢量光束。
