Infrared band pass filter having Si:NH layers with refraction index greater than 3.5

An infrared band pass filter, comprising:

• a first multilayer film, wherein the multilayer film comprises:
• a plurality of Si:NH layers, wherein a refraction index of each Si:NH layer is larger than 3.5 in a wavelength range between 800 nm and 1100 nm;
• and
• a plurality of first low refraction index layers, stacking with the plurality of Si:NH layers alternatively, wherein a material of the first low refraction index layer is selected from the group consisting of SiO2, Al2O3, TiO2, Nb2O5, Ta2O5, SiOH and SiNOH;
• a substrate, wherein the substrate is formed on the first multilayer film;
• and
• a second multilayer film, formed on the other surface of the substrate, opposite to the first multilayer film, and wherein the second multilayer film comprises:
• a plurality of Si:NH layers, wherein a refraction index of each Si:NH layer is greater than 3.5 in the wavelength range 800 nm and 1100 nm;
• and
• a plurality of second low refraction index layers, stacking with the plurality of Si:NH layers alternatively, wherein a material of the second low refraction index layer is selected from the group consisting of SiO2, Al2O3, TiO2, Nb2O5, Ta2O5, SiOH and SiNOH;
• wherein the substrate directly contacts the Si:NH layer of the first multilayer film and the Si:NH layer of the second multilayer film.

An infrared band pass filter, comprising:

• a first multilayer film, wherein the multilayer film comprises:
• a plurality of Si:NH layers, wherein a refraction index of each Si:NH layer is larger than 3.5 in a wavelength range between 800 nm and 1100 nm;
• and
• a plurality of first low refraction index layers, stacking with the plurality of Si:NH layers alternatively, wherein a refraction index of each first low refraction index layer is smaller than 3 in the wavelength range between 800 nm and 1100 nm;
• a substrate, wherein the substrate is formed on the first multilayer film;
• and
• a second multilayer film, formed on the other surface of the substrate, opposite to the first multilayer film, and wherein the second multilayer film comprises:
• a plurality of Si:NH layers, wherein a refraction index of each Si:NH layer is greater than 3.5 in the wavelength range between 800 nm and 1100 nm;
• and
• a plurality of second low refraction index layers, stacking with the plurality of Si:NH layers alternatively, wherein a refraction index of each second low refraction index layer is less than 3 in the wavelength range between 800 nm and 1100 nm;
• wherein the first multilayer film and the second multilayer film are symmetrical to each other with the substrate as a center plane of symmetry;
• wherein a layer farthest from the substrate in the first multilayer film is the first low refraction index layer, and a layer farthest from the substrate in the second multilayer film is the second low refraction index layer.