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光学整流方法产生太赫兹(THz)辐射常用的非线性发射晶体在THz波段都具有较高的折射率,使得很大一部分THz波由于晶体表面的菲涅尔反射而无法有效耦合输出.本文报道了GaP晶体THz波发射器输出表面上亚波长微棱锥增透结构的设计和实验研究.利用有效介质模型在理论上验证了亚波长光栅结构的增透效果,并进一步设计了适用于不同频段的增透结构的参数.实验中,通过微机械加工手段在GaP晶体输出端面刻划了多种亚波长微棱锥结构,验证了其增透效果及参数对增透频带的关系.理论与实验的符合证明该设计思想也可用于其他THz波发射晶体.
Optical rectification methods commonly used in the production of THz radiation non-linear emission crystal in the THz band have a higher refractive index, making a large part of the THz wave due to crystal surface Fresnel reflection and can not be effectively coupled output. GaP crystal THz wave emitter output surface of the sub-wavelength micro-pyramid antireflection structure design and experimental study.Using the effective medium model in theory to verify the sub-wavelength grating structure of antireflection effect, and further designed for different frequency band increase In the experiments, micro-pyramidal structures of sub-wavelength were inscribed on the output end of the GaP by micromachining, which verified the antireflection effect and the relationship between the parameters and the antireflection band. This design idea can also be used for other THz wave emitting crystals.