# US 11,307,019 B2 · Self-mix module utilizing filters

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- Number: US 11,307,019 B2
- Document ID: US11307019B2
- Status: Granted
- Kind: B2
- Application number: 17/160,093
- Filed: 2021-01-27
- Published: 2021-07-22
- Granted: 2022-04-19
- Earliest claimed: 2016-06-13
- Assignees: Vixar, Inc.
- Applicants: Vixar, Inc.; Vocalzoom Systems Ltd.
- Inventors: Klein Johnson; Tal Fishman; Tal Bakish
- Web page: https://patentgrep.com/patent/US11307019B2

## CPC

- G01B 9/02092: {Self-mixing interferometers, i.e. feedback of light from object into laser cavity}
- H01S 5/0028: {Laser diodes used as detectors}
- G01B 9/02015: characterised by the beam path configuration
- G01B 9/0205: {of probe head}
- G01S 7/4814: {of transmitters alone}
- G01S 7/4916: {using self-mixing in the laser cavity}
- G02B 27/30: Collimators
- H01S 5/00: Semiconductor lasers (superluminescent diodes H10H20/00)
- H01S 5/02326: Arrangements for relative positioning of laser diodes and optical components, e.g. grooves in the mount to fix optical fibres or lenses
- H01S 5/0239: Combinations of electrical or optical elements
- H01S 5/0262: {Photo-diodes, e.g. transceiver devices, bidirectional devices (H01S5/0265 takes precedence)}
- H01S 5/18305: {with emission through the substrate, i.e. bottom emission}
- G01B 2290/25: Fabry-Perot in interferometer, e.g. etalon, cavity
- G01S 17/32: using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
- G01S 17/50: Systems of measurement based on relative movement of target
- H01S 5/02253: using lenses
- H01S 5/183: having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
- H01S 2301/02: ASE (amplified spontaneous emission), noise; Reduction thereof
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A system and method for generating, enhancing, and detecting the amplitude and phase modulation of a laser under a condition of self-mixing is provided. The system may comprise a laser and a detector to extract the characteristic self-mix signal, which is then interpreted using algorithms implemented in hardware or software. In the case of the laser being a Vertical Cavity Surface Emitting laser (VCSEL), the output signal can be detected by monitoring the surface light emission by means of a beam splitter, or in some embodiments as emission from the bottom surface of the laser. In some embodiments, the system may further comprise a wavelength filter such as an etalon in the signal path.

## Claims

### Claim 1

A sensor device for laser light emission comprising:
at least one partially bottom-emitting VCSEL laser emitting a light from at least one aperture, the laser comprising a cavity, a top surface mirror and a bottom surface mirror;
a detector;
a wavelength filter in a fixed position relative to the cavity; and
a first optical lens for approximately focusing a portion of the light emitted by the laser onto a target surface;
wherein a first optical path carries a first portion of the light emitted from the laser between the laser, the first optical lens, and the target surface and a second optical path carries a second portion of the light emitted from the laser between the laser and the detector;
wherein the filter enhances signal amplitude of the second portion of the light;
wherein the target surface is disposed only within the first optical path; and
wherein the filter is disposed within the second optical path between the laser and the detector.

### Claim 2 (depends on 1)

The sensor device of claim 1, wherein the filter is one of a grating or an etalon.

### Claim 3 (depends on 1)

The sensor device of claim 1, wherein the laser has multiple apertures for emitting light.

### Claim 4

A packaged sensor device comprising:
a housing;
a VCSEL laser having at least one mirror and a substrate, the VCSEL laser emitting a light from an aperture, the light having a wavelength, the VCSEL being at least partially received by the housing;
a detector mounted to a substrate at a first end of the housing;
a wavelength filter disposed between the laser and the detector; and
at least one optical lens at a second end of the housing;
wherein a first portion of the light is directed through the at least one lens and onto a target a second portion of the light is directed through the filter and onto the detector, and wherein the filter enhances signal amplitude of the second portion of the light.

### Claim 5 (depends on 4)

The packaged sensor device of claim 4, wherein the filter is an etalon.

### Claim 6 (depends on 4)

The packaged sensor device of claim 4, wherein the detector is selected from the group consisting of: a photodetector, PIN photodetector, a resonant cavity photodetector, or an avalanche photodiode.

### Claim 7 (depends on 4)

The packaged sensor device of claim 4, wherein the filter has two faces in parallel, wherein each face has a mirror that is highly reflective at the wavelength.

### Claim 8 (depends on 4)

The packaged sensor device of claim 4, wherein the housing has at least one feature for passive alignment and assembly of the laser and the filter.

### Claim 9 (depends on 4)

The packaged sensor device of claim 4, wherein the substrate has a pattern of apertures on at least one side for the suppression of spontaneous emission of light.

### Claim 10

A sensor device for laser light emission comprising:
at least one VCSEL laser emitting a light from at least one aperture, the laser comprising a cavity and at least one mirror;
a detector;
a wavelength filter in a fixed position relative to the cavity, wherein the filter enhances signal amplitude of light directed to the detector;
a first optical lens that approximately focuses a first portion of the laser emission onto a target surface; and
a beam splitter between the first optical lens and the laser, wherein the beam splitter redirects a second portion of the light from the mirror onto the detector;
wherein a first optical path carries the first portion of the light between the laser and the target surface and a second optical path carries the second portion of the light emitted between the beam splitter and the detector.

### Claim 11 (depends on 10)

The sensor device of claim 10, further comprising a second optical lens between the beam splitter and the detector, wherein the second optical lens approximately collimates light from the beam splitter and directs it onto the detector.

### Claim 12 (depends on 10)

The sensor device of claim 10, wherein the target surface is disposed only within the first optical path.

### Claim 13 (depends on 10)

The sensor device of claim 10, wherein the filter is disposed only within the second optical path.

### Claim 14 (depends on 13)

The sensor device of claim 13, wherein the beam splitter is positioned at an angle relative to an optical axis of the laser.

### Claim 15 (depends on 1)

The sensor device of claim 1, further comprising a second optical lens for approximately collimating light emitted from the bottom surface mirror and directing it towards the detector.

### Claim 16 (depends on 1)

The sensor device of claim 1, wherein the at least one partially bottom-emitting VCSEL laser has a top-to-bottom emission ratio of 2:1.

### Claim 17 (depends on 1)

The sensor device of claim 1, wherein the at least one partially bottom-emitting VCSEL laser has a top-to-bottom emission ratio between 1:1 and 10:1.

### Claim 18 (depends on 1)

The sensor device of claim 1, further comprising a substrate, wherein the bottom surface is coated with a low-reflectivity coating.

### Claim 19 (depends on 1)

The sensor device of claim 1, wherein relative reflectivities of the top surface mirror and the bottom surface mirror are chosen for a selected ratio of light emitted from a top surface to light emitted from a bottom surface.

### Claim 20 (depends on 1)

The sensor device of claim 1, wherein the filter has at least one passband of narrow extent and of a wavelength such that the light can be tuned to operate on a steep region of a passband.