体布拉格光栅光谱滤波器特性研究

Characteristics of volume Bragg grating spectral filter

高透过率、窄光谱带宽、高抑制比的滤波器件是提升光学系统光谱纯度的核心部件,也是近年来新型光学器件领域研究的热门方向。传统的滤波器件不能够同时满足透过率、光谱带宽以及带外抑制的要求,而文中研究的体光栅作为一种新型的光栅,衍射效率大于90%,光谱带宽在100 pm左右,并且拥有一定的角度滤波特性。依据耦合波理论,理论仿真了各个光栅参数(光栅厚度、折射率调制度、光栅周期、光栅倾角)对光栅衍射效率及光谱带宽的影响,定量地给出了参数影响的大小,为体光栅的设计提供了理论指导。设计了体光栅测试系统,通过实验验证了体光栅的衍射效率、光谱带宽、角度选择性,实验结果与理论较为符合,为体光栅的实际应用提供了实验数据支持。

The filter element with high transmittance, narrow spectral bandwidth and high suppression ratio is the core component to improve the spectral purity of an optical system, and it is also a hot research direction in the field of new optical devices in recent years. The traditional filter elements can not meet the requirements of transmittance, spectral bandwidth and out-of-band suppression simultaneously. As a new type of grating, the diffraction efficiency of the volume grating is usually greater than 90 %, the spectral bandwidth is about 100 pm,and it has angle filtering characteristics. Based on the coupled-wave theory, the influence of grating parameters(grating thickness, refractive index modulation, grating period, grating inclination angle) on the diffraction efficiency and spectral bandwidth of the grating was theoretically simulated, and the influence of parameters was quantitatively given, which provided theoretical guidance for the design of volume grating. The volume grating test system was designed, and the diffraction efficiency, spectral bandwidth and angle selectivity of the volume grating were verified by experiments. The experimental results are in agreement with the theory. The diffraction efficiency is greater than 90%, and the spectral bandwidth is about 100 pm, which provides support for the practical application of the volume grating.