Optical filter and sensor system

Patent metadata

Field	Value
Publication number	US-2016266289-A1
Application number	US-201615158191-A
Country	US
Kind code	A1
Filing date	May 18, 2016
Priority date	Jul 16, 2012
Publication date	Sep 15, 2016
Grant date	—

Abstract

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.

First claim

1 - 20 . (canceled)

21 . An optical filter, comprising:
a filter stack comprising:
a plurality of hydrogenated silicon layers, wherein the plurality of hydrogenated silicon layers have a refractive index of greater than 3 over a wavelength range of 800 nm to 1100 nm; and
a plurality of lower-refractive-index layers, wherein the plurality of lower-refractive-index layers have a refractive index of less than 3 over the wavelength range of 800 nm to 1100 nm, and wherein the plurality of lower-refractive-index layers are stacked in alternation with the plurality of hydrogenated silicon layers; and
wherein the optical filter has a passband at least partially overlapping with the wavelength range of 800 nm to 1100 nm,
wherein the passband has a center wavelength that shifts by less than 20 nm in magnitude with a change in an incidence angle between 0° to 30°.

22 . The optical filter of claim 21 , wherein the plurality of hydrogenated silicon layers each have a refractive index of greater than 3.6 at a wavelength of 830 nm.

23 . The optical filter of claim 21 , wherein the plurality of hydrogenated silicon layers each have a refractive index of greater than 3.5 over the wavelength range of 800 nm to 1100 nm.

24 . The optical filter of claim 21 , wherein the plurality of hydrogenated silicon layers each have a refractive index of greater than 3.6 over the wavelength range of 800 nm to 1100 nm.

25 . The optical filter of claim 21 , wherein the plurality of lower-refractive-index layers each have a refractive index of less than 2.5 over the wavelength range of 800 nm to 1100 nm.

26 . The optical filter of claim 21 , wherein the plurality of lower-refractive-index layers each have a refractive index of less than 2 over the wavelength range of 800 nm to 1100 nm.

27 . The optical filter of claim 21 , wherein the passband has a center wavelength that shifts by less than 15 nm in magnitude with a change in the incidence angle between 0° to 30°.

28 . The optical filter of claim 21 , wherein the passband has a center wavelength that shifts by about 12.2 nm in magnitude with a change in the incidence angle between 0° to 30°.

29 . The optical filter of claim 21 , wherein the plurality of lower-refractive-index layers are each composed of silicon dioxide (SiO 2 ), aluminum oxide (Al2O3), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5), or a mixture thereof.

30 . The optical filter of claim 21 , wherein the optical filter has a transmittance level, within the passband, of greater than 90% over the wavelength range of 800 nm to 1100 nm.

31 . The optical filter of claim 21 , wherein the optical filter has a blocking level, outside of the passband, of greater than OD2 over a wavelength range of 400 nm to 1100 nm.

32 . The optical filter of claim 21 , wherein the optical filter is a long-wavelength-pass edge filter, and wherein the passband has an edge wavelength in the wavelength range of 800 nm to 1100 nm.

33 . The optical filter of claim 21 , wherein the optical filter is a bandpass filter, and wherein the passband has a center wavelength in the wavelength range of 800 nm to 1100 nm.

34 . The optical filter of claim 21 , wherein the passband has a full width at half maximum (FWHM) of less than 50 nm.

35 . The optical filter of claim 21 , further comprising:
a substrate, wherein the filter stack is disposed on a first surface of the substrate and a coating is disposed on a second surface of the substrate opposite the first surface.

36 . The optical filter of claim 35 , wherein the coating is an antireflective (AR) coating.

37 . The optical filter of claim 21 , wherein the optical filter has a total coating thickness of less than 10 μm.

38 . The optical filter of claim 21 , forming part of a sensor system including a light source for emitting light at an emission wavelength within the passband of the optical filter, and a sensor for detecting the emitted light,
wherein the optical filter receives the emitted light from the light source and transmits the emitted light to the sensor.

39 . The optical filter of claim 21 , wherein the plurality of hydrogenated silicon layers are each deposited by pulsed direct current (DC) sputtering.

40 . A sensor system, comprising:
an optical filter, having a passband including an emission wavelength and at least partially overlapping with a wavelength range of 800 nm to 1100 nm, being disposed to receive emitted light and transmit the emitted light, wherein the emitted light is emitted, from a light source, at the emission wavelength in the wavelength range of 800 nm to 1100 nm, and wherein the optical filter includes a filter stack including:
a plurality of hydrogenated silicon layers,
wherein the plurality of hydrogenated silicon layers each have a refractive index of greater than 3 over the wavelength range of 800 nm to 1100 nm; and

a plurality of lower-refractive-index layers,
wherein the plurality of lower-refractive-index layers each have a refractive index of less than 3 over the wavelength range of 800 nm to 1100 nm, and wherein the plurality of lower-refractive-index layers are stacked in alternation with the plurality of hydrogenated silicon layers,

wherein the passband has a center wavelength that shifts by less than 20 nm in magnitude with a change in an incidence angle between 0° to 30°.

41 . The sensor system of claim 40 , wherein the optical filter is disposed directly on a sensor.

42 . The sensor system of claim 40 , further comprising: a sensor, wherein the sensor system is a proximity sensor system, the emitted light is directed toward a target, the optical filter is disposed to receive the emitted light after reflection by the target, and the sensor is a proximity sensor for detecting the emitted light and sensing a proximity of the target.

43 . The sensor system of claim 40 , further comprising: a sensor, wherein the sensor system is a three-dimensional (3D) imaging system, the emitted light is directed toward a target, the optical filter is disposed to receive the emitted light after reflection by the target, and the sensor is a 3D image sensor for detecting the emitted light and providing a 3D image of the target.

44 . The sensor system of claim 43 , wherein the 3D imaging system is a gesture-recognition system, the target is a user of the gesture-recognition system, and the sensor system further includes:
a processing system for processing the 3D image of the user to recognize a gesture of the user.

45 . The sensor system of claim 40 , further comprising: a sensor, wherein the sensor is a charge-coupled device (CCD) chip or a complementary metal oxide semiconductor (CMOS) chip.

46 . The sensor system of claim 40 , further comprising: a sensor, wherein the optical filter is formed directly on the sensor by using wafer-level processing.

47 . The sensor system of claim 40 , wherein the optical filter further includes:
a substrate, wherein the filter stack is disposed on a first surface of the substrate; and an antireflective (AR) coating is disposed on a second surface of the substrate opposite the first surface.

48 . A system, comprising:
an optical filter, having a passband including an emission wavelength and at least partially overlapping with a wavelength range of 800 nm to 1100 nm; wherein the optical fil

Assignees

• Viavi Solutions Inc

Inventors

• Hendrix Karen Denise
• Bradley Jr Richard A
• Grigonis Marius
• Ockenfuss Georg J

Classifications

• C23C14/548

  Controlling the composition · CPC title

• G02B5/281 Primary

  designed for the infrared light · CPC title

• C23C14/08

  Oxides (C23C14/10 takes precedence) · CPC title

• G02B1/115

  Multilayers · CPC title

• G02B5/207

  comprising semiconducting materials · CPC title