Optical filter and sensor system
An optical filter having a passband at least partially overlapping with a wavelength range of 800 nm to 1100 nm is provided. The optical filter includes a filter stack formed of hydrogenated silicon layers and lower-refractive index layers stacked in alternation. The hydrogenated silicon layers each have a refractive index of greater than 3 over the wavelength range of 800 nm to 1100 nm and an extinction coefficient of less than 0.0005 over the wavelength range of 800 nm to 1100 nm.
1. An optical device, comprising:
a near infrared band pass filter, comprising:
a substrate having a first side and a second side;
a first set of layers on the first side, wherein the first set of layers includes silicon and hydrogen;
a second set of layers on the first side, wherein the second set of layers includes oxygen; and
a third set of layers on the second side, whether the third set of layers includes oxygen.
2. The optical device of claim 1 , wherein one or both of the second set or the third set of layers includes silicon.
3. The optical device of claim 1 , wherein one or both of the second set or the third set of layers is silicon dioxide.
4. The optical device of claim 1 , wherein one or both of the second set or the third set of layers includes tantalum.
5. The optical device of claim 1 , wherein one or both of the second set or the third set of layers includes titanium.
6. The optical device of claim 1 , wherein total quantity of layers on the first side is between 25 and 48.
7. The optical device of claim 1 , wherein the optical device is configured for use in a 3D image sensing system.
8. The optical device of claim 1 , wherein the band pass filter has a center wavelength that shifts less than 15 nm in magnitude with a change in incidence angle from 0° to 30°.
9. An optical device, comprising:
a first set of layers including silicon and hydrogen; and
a second set of layers including oxygen;
wherein the optical device is a near infrared bandpass filter that has a center wavelength that shifts by less than 15 nm in magnitude with a change in incidence angle from 0° to 30°.
10. The optical device of claim 9 , wherein the second set of layers includes silicon.
11. The optical device of claim 9 , wherein the second set of layers is silicon dioxide.
12. The optical device of claim 9 , wherein the second set of layers includes tantalum.
13. The optical device of claim 9 , wherein the near infrared band pass filter has a full width half maximum (FWHM) that is less than 50 nm.
14. The optical device of claim 9 , wherein the passband shifts by less than 13 nm in magnitude with a change in incidence angle from 0° to 30°.
15. An optical system, comprising:
a light source for emitting light having a wavelength between 800-1100 nm; and
a filter comprising:
a first set of layers including silicon and hydrogen; and
a second set of layers including oxygen;
wherein the filter is designed for substantially allowing light in a wavelength range that includes the wavelength between 800-1100 nm to pass through it and exhibits a blocking level greater than OD2 between 400 nm to 1100 nm but outside of the wavelength range.
16. The optical system of claim 15 , wherein the filter has a blocking level of greater than OD3 for wavelengths between 300 nm to 1100 nm that are outside of the wavelength range.
17. The optical system of claim 15 , wherein the filter has a center wavelength that shifts by less than 20 nm in magnitude with a change in incidence angle from 0° to 30°.
18. The optical system of claim 15 , wherein the first set of layers and the second set of layers are on a first side of a substrate and an antireflective coating is on a second side of the substrate.
19. The optical system of claim 15 , wherein the first set of layers and the second set of layers are on a first side of a substrate and a third set of layers that includes oxygen is on a second side of the substrate.