# US 11,443,547 B2 · Waveguide device incorporating beam direction selective light absorber

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- Number: US 11,443,547 B2
- Document ID: US11443547B2
- Status: Granted
- Kind: B2
- Application number: 16/990,840
- Filed: 2020-08-11
- Published: 2020-11-26
- Granted: 2022-09-13
- Earliest claimed: 2013-07-31
- Assignees: DigiLens Inc.
- Applicants: DigiLens Inc.
- Inventors: Milan Momcilo Popovich; Jonathan David Waldern
- Web page: https://patentgrep.com/patent/US11443547B2

## CPC

- G06V 40/1324: {by using geometrical optics, e.g. using prisms (G06V40/1312 takes precedence)}
- G02B 5/1828: {having means for producing variable diffraction (controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955)}
- G02B 6/0026: {Wavelength selective element, sheet or layer, e.g. filter or grating}
- G02B 6/0076: {Stacked arrangements of multiple light guides of the same or different cross-sectional area}
- G02B 6/34: utilising prism or grating {(G02B6/293 takes precedence)}
- G02B 26/0808: {by means of one or more diffracting elements}
- G02B 27/4277: {being separated by an air space}
- G06V 40/1318: {using electro-optical elements or layers, e.g. electroluminescent sensing}
- H10F 39/198: {Contact-type image sensors [CIS]}
- G02B 6/0056: {for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements}
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A contact image sensor having an illumination source; a first SBG array device; a transmission grating; a second SBG array device; a waveguiding layer including a multiplicity of waveguide cores separated by cladding material; an upper clad layer; and a platen. The sensor further includes: an input element for coupling light from the illumination source into the first SBG array; a coupling element for coupling light out of the cores into output optical paths coupled to a detector having at least one photosensitive element.

## Claims

### Claim 1

A waveguide device comprising:
a source of light;
a waveguide having a first total internal reflection (TIR) surface and a second TIR surface facing the outside world;
an input coupler for coupling the light into a TIR path in the waveguide;
a grating for extracting light from the waveguide via the first TIR surface; and
a light absorbing material disposed in at least one region of the waveguide, wherein the light absorbing material provides directional selectivity to the TIR light.

### Claim 2 (depends on 1)

The waveguide device of claim 1, wherein said light absorbing material comprises non-absorbing regions comprising portions of said substrate surface at which total internal reflection can take place.

### Claim 3 (depends on 2)

The waveguide device of claim 2, wherein said non-absorbing regions are portions of said first TIR surface or second TIR surface textured to scatter light or coated to provide partial reflection of light.

### Claim 4 (depends on 1)

The waveguide device of claim 1, wherein the source of light is optically coupled to said waveguide.

### Claim 5 (depends on 4)

The waveguide device of claim 4, wherein said light is collimated before being coupled into said waveguide.

### Claim 6 (depends on 4)

The waveguide device of claim 4, wherein said light is polarized before being coupled into said waveguide.

### Claim 7 (depends on 1)

The waveguide device of claim 1, wherein at least one of said input coupler and said grating for extracting light is one of a forward mode switchable Bragg grating, a reverse mode switchable Bragg grating, a stack of thin switchable gratings, or a surface relief grating.

### Claim 8 (depends on 1)

The waveguide device of claim 1, wherein said input coupler is patterned into a multiplicity of elongate grating elements aligned orthogonal to a light propagation direction of said waveguide.

### Claim 9 (depends on 1)

The waveguide device of claim 1, wherein said optical substrate is divided into a pair of substrates sandwiching said input coupler, and transparent electrodes are applied to a surface of each substrate.

### Claim 10 (depends on 1)

The waveguide device of claim 1, wherein said input coupler comprises a plurality of grating elements switchable between a diffracting state and a non-diffracting state, wherein said grating elements are switched sequentially.

### Claim 11 (depends on 1)

The waveguide device of claim 1, wherein said input coupler is a reflection grating.

### Claim 12 (depends on 1)

The waveguide device of claim 1, wherein said light absorbing material comprises light absorbing regions and non-absorbing regions formed in a grid pattern.

### Claim 13 (depends on 1)

The waveguide device of claim 1, wherein external faces of said waveguide abut air or a low refractive index material layer.

### Claim 14 (depends on 1)

The waveguide device of claim 1, further comprising an optical structure including at least one grating layer providing polarization selectivity to the TIR light.

### Claim 15 (depends on 14)

The waveguide device of claim 14, wherein polarization selectivity is dependent at least in part on the diffraction efficiency polarization sensitivity of the at least one grating layer.

### Claim 16 (depends on 14)

The waveguide device of claim 14, wherein said optical structure is configured to direct stray light into waveguide light paths that are intercepted by said absorbing material.

### Claim 17 (depends on 14)

The waveguide device of claim 14, wherein said optical structure comprises at least one selected from the group of a grating, a transmission grating, and at least one polarization control layer.

### Claim 18 (depends on 14)

The waveguide device of claim 14, wherein said optical structure comprises at least one grating and at least one polarization control layer configured as a stack.