Characteristics of volume Bragg grating spectral filter

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.