# US 10,871,639 B2 · Optical cross-coupling mitigation systems for wavelength beam combining laser systems

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,871,639 B2
- Document ID: US10871639B2
- Status: Granted
- Kind: B2
- Application number: 16/559,834
- Filed: 2019-09-04
- Published: 2020-02-20
- Granted: 2020-12-22
- Earliest claimed: 2010-03-05
- Assignees: Teradiode, Inc.
- Applicants: Bien Chann
- Inventors: Bien Chann
- Web page: https://patentgrep.com/patent/US10871639B2

## CPC

- G02B 19/0057: {in the form of a laser diode array, e.g. laser diode bar (semiconductor laser arrays with beam combining arrangement H01S5/4012)}
- G02B 6/0208: {characterised by their structure, wavelength response (G02B6/02114, G02B6/02171, G02B6/02195 take precedence; multiple layer cores or claddings G02B6/036, protective coverings G02B6/4429)}
- G02B 6/14: Mode converters
- G02B 6/262: {Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements}
- G02B 6/29317: {Light guides of the optical fibre type}
- G02B 6/32: having lens focusing means {positioned between opposed fibre ends (with lens being an integral part of the single fibre end G02B6/262)}
- G02B 19/0014: {at least one surface having optical power}
- G02B 19/0028: {refractive and reflective surfaces, e.g. non-imaging catadioptric systems}
- G02B 27/0905: {Dividing and/or superposing multiple light beams}
- G02B 27/1006: {for splitting or combining different wavelengths (G02B27/1086, G02B27/141 take precedence)}
- G02B 27/4244: {in wavelength selecting devices (spectrometry G01J)}
- H01S 5/4062: {with an external cavity or using internal filters, e.g. Talbot filters}
- G02B 2005/1804: {Transmission gratings}
- H01S 3/08063: {Graded reflectivity, e.g. variable reflectivity mirror}
- H01S 5/141: {using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence)}
- H01S 5/4068: {with lateral coupling by axially offset or by merging waveguides, e.g. Y-couplers}
- H01S 5/4087: {emitting more than one wavelength}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- 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

## Abstract

In various embodiments, wavelength beam combining laser systems incorporate optical cross-coupling mitigation systems and/or engineered partially reflective output couplers in order to reduce or substantially eliminate unwanted back-reflection of stray light.

## Claims

### Claim 1

A laser system comprising:
an array of beam emitters each emitting a beam having a different wavelength;
focusing optics for focusing the beams toward a dispersive element;
a dispersive element for receiving and dispersing the focused beams, thereby forming a multi-wavelength beam; and
an output coupler comprising (i) a beam-receiving portion for receiving the multi-wavelength beam, reflecting a first portion thereof back to the array of beam emitters via the dispersive element, and transmitting a second portion thereof as an output beam composed of multiple wavelengths, and (ii) a non-reflective portion.

### Claim 2 (depends on 1)

The laser system of claim 1, wherein the beam-receiving portion of the output coupler is at least as large as a diameter of the multi-wavelength beam.

### Claim 3 (depends on 1)

The laser system of claim 1, wherein the beam-receiving portion of the output coupler protrudes above the non-reflective portion.

### Claim 4 (depends on 1)

The laser system of claim 1, wherein the non-reflective portion at least partially surrounds the beam-receiving portion.

### Claim 5 (depends on 1)

The laser system of claim 1, wherein a reflectivity to the multi-wavelength beam of the non-reflective portion is less than 1%.

### Claim 6 (depends on 1)

The laser system of claim 1, wherein a reflectivity to the multi-wavelength beam of the beam-receiving portion is less than approximately 15%.

### Claim 7 (depends on 1)

The laser system of claim 1, wherein a reflectivity to the multi-wavelength beam of the beam-receiving portion ranges from approximately 2% to approximately 10%.

### Claim 8 (depends on 1)

The laser system of claim 1, further comprising a non-reflective coating disposed over the non-reflective portion of the output coupler.

### Claim 9 (depends on 1)

The laser system of claim 1, further comprising an end cap over the beam-receiving portion of the output coupler.

### Claim 10 (depends on 1)

The laser system of claim 1, further comprising an optical fiber positioned to receive the output beam.

### Claim 11 (depends on 1)

The laser system of claim 1, further comprising a workpiece positioned to receive the output beam.

### Claim 12 (depends on 1)

The laser system of claim 1, further comprising an optical element for focusing the multi-wavelength beam toward the output coupler.

### Claim 13 (depends on 12)

The laser system of claim 12, wherein the optical element comprises at least one of a cylindrical lens or a spherical lens.

### Claim 14 (depends on 1)

The laser system of claim 1, further comprising a cross-coupling mitigation system for receiving and transmitting the multi-wavelength beam while reducing cross-coupling thereof.

### Claim 15 (depends on 14)

The laser system of claim 14, wherein the beam-receiving portion of the output coupler is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the cross-coupling mitigation system.

### Claim 16 (depends on 14)

The laser system of claim 14, wherein at least a portion of the cross-coupling mitigation system is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the dispersive element.

### Claim 17 (depends on 14)

The laser system of claim 14, wherein the cross-coupling mitigation system comprises an afocal telescope.

### Claim 18 (depends on 14)

The laser system of claim 14, wherein the cross-coupling mitigation system comprises a first optical element having a first focal length and a second optical element having a second focal length, the first optical element being disposed optically upstream of the second optical element.

### Claim 19 (depends on 18)

The laser system of claim 18, wherein the first focal length is at least two times greater than the second focal length.

### Claim 20 (depends on 18)

The laser system of claim 18, wherein the first focal length is at least seven times greater than the second focal length.

### Claim 21 (depends on 18)

The laser system of claim 18, wherein each of the first and second optical elements comprises a lens.

### Claim 22 (depends on 18)

The laser system of claim 18, wherein the first optical element is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the dispersive element.

### Claim 23 (depends on 18)

The laser system of claim 18, wherein the beam-receiving portion of the output coupler is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the second optical element.

### Claim 24 (depends on 18)

The laser system of claim 18, wherein an optical distance between the first and second optical elements is approximately equal to a sum of the first and second focal lengths.