太赫兹立体相位光栅衍射特性分析

Diffraction characteristics analysis of multi-depth phase modulation grating in terahertz band

针对太赫兹谱成像对宽光谱、高光能利用率、实时探测分光器件的需求,提出了一种太赫兹立体相位光栅(MPMG)分光器件。MPMG通过刻槽深度的变化引入光程差,实现对入射光的相位调制,从而使反射太赫兹波前的不同区域具有不同的相位信息,其零级衍射光具备分光能力。在分析MPMG衍射场光强分布的基础上,讨论了光栅参数对衍射场分布的影响,并通过实验验证了MPMG的衍射特性。结果表明,MPMG各光栅单元在0.5 THz、0.34 THz的衍射效率理论值与实测值相吻合,证明了MPMG的零级衍射光具备分光能力。

To meet the requirements of terahertz spectral imaging for wide spectral range,high efficiency and real-time detection of spectrometers,a Multi-depth Phase Modulation Grating(MPMG)in terahertz band is proposed.The phase modulation of incident light is realized by introducing optical path difference resulted from the change of groove depth,so that different regions of reflecting terahertz wave front have different phase information.Based on the analysis of the intensity distribution of the diffraction field of the MPMG,the influence of grating parameters on the distribution of the diffraction field is discussed.The diffraction characteristics of the MPMG are verified by experiments.The experiment results indicate that the measurements of the 0th-and±1st-order diffraction efficiency at 0.5 and 0.34 THz obtained by experiment and simulation are in good agreement.It suggests that 0th order diffraction of the MPMG has the ability of splitting light.