# US 2024/0201016 A1 · Polarizing filter and polarimetric image sensor integrating such a filter

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- Number: US 2024/0201016 A1
- Document ID: US20240201016A1
- Status: Published application
- Kind: A1
- Application number: 18/537,948
- Filed: 2023-12-13
- Published: 2024-06-20
- Earliest claimed: 2022-12-20
- Assignees: Commissariat à I'Énergie Atomique et aux Énergies Alternatives
- Applicants: Commissariat à I'Énergie Atomique et aux Énergies Alternatives
- Inventors: François Deneuville
- Web page: https://patentgrep.com/patent/US20240201016A1

## CPC

- G01J 4/04: Polarimeters using electric detection means (G01J4/02 takes precedence)
- G02B 5/3058: {comprising electrically conductive elements, e.g. wire grids, conductive particles}
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- G01J 3/0224: {using polarising or depolarising elements}
- G01J 3/2803: {using photoelectric array detector}
- G02B 3/0056: {arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses (G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085)}
- G02B 5/3008: {comprising dielectric particles, e.g. birefringent crystals embedded in a matrix}
- G02B 2207/101: Nanooptics
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

A polarizing filter intended to be arranged in front of an image sensor including a plurality of pixels, the filter including, for each pixel, a polarizing structure including a plurality of parallel metal bars, each bar being coated with an absorbing stack including: —a tungsten layer; —a silicon layer, coating the tungsten layer; and —a dielectric layer, coating the silicon layer.

## Claims

### Claim 1

Polarizing filter intended to be arranged in front of an image sensor comprising a plurality of pixels, the filter comprising, for each pixel, a polarizing structure comprising a plurality of parallel metal bars, each bar being coated with an absorbing stack comprising:
a tungsten layer;
a silicon layer, coating the tungsten layer; and
a dielectric layer, coating the silicon layer.

### Claim 2 (depends on 1)

Filter according to claim 1, wherein the metal bars are made of a material different from tungsten, preferably of aluminum.

### Claim 3 (depends on 2)

Filter according to claim 2, wherein the tungsten layer has a thickness greater than 40 nm, preferably greater than 60 nm.

### Claim 4 (depends on 1)

Filter according to claim 1, wherein the metal bars are made of tungsten.

### Claim 5 (depends on 4)

Filter according to claim 4, wherein the metal bars and the tungsten layer have a cumulated thickness greater than 40 nm, preferably greater than 60 nm.

### Claim 6 (depends on 1)

Filter according to claim 1, wherein the silicon layer has a thickness in the range from 20 to 100 nm, preferably from 30 to 50 nm, for example equal to approximately 39 nm.

### Claim 7 (depends on 1)

Filter according to claim 1, wherein the dielectric layer is made of silicon oxide.

### Claim 8 (depends on 1)

Filter according to claim 1, wherein the dielectric layer is formed of a stack of a plurality of layers of dielectric materials having refraction indices lower than that of silicon.

### Claim 9 (depends on 1)

Polarimetric image sensor formed inside and on top of a semiconductor substrate, the sensor comprising:
a plurality of pixels, each comprising a photodetector formed in the semiconductor substrate; and
a polarizing filter according to claim 1, the filter being arranged on the side of an illumination surface of the photodetectors.

### Claim 10 (depends on 9)

Sensor according to claim 9, wherein said plurality of pixels comprises at least first and second pixels adapted to measuring radiations according to respectively first and second distinct polarizations, the polarization structure of the first pixel) being adapted to predominantly transmitting a radiation according to the first polarization and the polarization structure of the second pixel) being adapted to predominantly transmitting a radiation according to the second polarization.

### Claim 11 (depends on 10)

Sensor according to claim 10, wherein said plurality of pixels further comprises third and fourth pixels adapted to measuring radiations according to respectively third and fourth distinct polarizations, different from the first and second polarizations, the polarization structure of the third pixel) being adapted to predominantly transmitting a radiation according to the third polarization and the polarization structure of the fourth pixel) being adapted to predominantly transmitting a radiation according to the fourth polarization.

### Claim 12 (depends on 11)

Sensor according to claim 11, wherein the first, second, third and fourth polarizations are linear polarizations along first, second, third and fourth directions respectively forming 0°, 90°, 45° and 135° angles with a reference direction.

### Claim 13 (depends on 9)

Sensor according to claim 9, further comprising a polarization router comprising a two-dimensional metasurface arranged on the side of the polarizing filter opposite to the photodetectors, the metasurface comprising a two-dimensional array of pads.

### Claim 14 (depends on 11)

Sensor according to claim 11, further comprising a polarization router comprising a two-dimensional metasurface arranged on the side of the polarizing filter opposite to the photodetectors, the metasurface comprising a two-dimensional array of pads, wherein the two-dimensional metasurface comprises:
a first portion located vertically in line with the first and second pixels adapted to predominantly transmitting:
a radiation according to the first polarization towards the first pixel; and
a radiation according to the second polarization towards the second pixel, and
a second portion) located vertically in line with the third and fourth pixels adapted to predominantly transmitting:
a radiation according to the third polarization towards the third pixel); and
a radiation according to the fourth polarization towards the fourth pixel.

### Claim 15 (depends on 9)

Sensor according to claim 9, further comprising a plurality of first microlenses extending in front of a pair of adjacent pixels of the sensor.

### Claim 16 (depends on 15)

Sensor according to claim 15, wherein the first microlenses each have an elongated shape.

### Claim 17 (depends on 13)

Sensor according to claim 13, further comprising a plurality of first microlenses extending in front of a pair of adjacent pixels of the sensor, wherein the first microlenses are:
A) arranged on the side of a surface of the two-dimensional metasurface opposite to the photodetectors; or
B) interposed between the photodetectors and the two-dimensional metasurface.

### Claim 18 (depends on 17)

Sensor according to claim 17, in its option B), further comprising a plurality of second microlenses distinct from the first microlenses and arranged on the side of a surface of the two-dimensional metasurface opposite to the photodetectors, each second microlens extending in front of a pair of adjacent pixels of the sensor.

### Claim 19 (depends on 18)

Sensor according to claim 18, wherein each second microlens has an elongated shape.