Optical filter plate

An optical filter, characterized in that, the optical filter comprises a substrate and a first set of films disposed on a first surface of the substrate, wherein the first set of films comprises a high refractive index film layer, a low refractive index film layer, and a matching film layer;

• a material of the matching film layer comprises a nitrogen-doped silicon mixture having a chemical formula SiNy, a nitrogen-doped germanium mixture having a chemical formula GeNy, or a nitrogen-doped silicon germanium mixture having a chemical formula SixGe1-xNy, wherein 0<x<1, and 0<y≤0.1;
• wherein, in a wavelength range from 780 nm to 3000 nm, a refractive index of the high refractive index film layer is greater than a refractive index of the low refractive index film layer, and a refractive index of the matching film layer is not equal to a refractive index of its adjacent film layer;
• wherein along a direction away from the substrate, the first set of films has a structure in one of the following forms:
• (L3-L1-L3-L2)s-L3-L1;
• (L1-L3)2-(L2-L3-L1-L3)s-L1-L3;
• (L1-L3)s-(L2-(L1-L3)p-L1-L2)q-(L1-L3)rL1;
• (L3-L1)s-(L2-(L1-L3)p-L1-L2)q-(L3-L1)rL3-L1-(L2-(L1-L3)t-L1-L2)n;
• or
• (L3-L1)s-(L3-L1)rL3-(L2-(L1-L3)p-L1-L2)q-(L3-L1)rL3-(L2-(L1-L3)t-L1-L2)n-(L3-L1)r,
• in the structural of the first set of films, L1 represents the high refractive index film layer, L3 represents the low refractive index film layer, L2 represents the matching film layer, p, q, r, and s represent a number of repetitions of a structure in parentheses, wherein p, q, r, and s are integers greater than or equal to 0.