# US 12,763,544 B2 · Mode-matching a plurality of optical beams to a corresponding plurality of optical power amplifiers

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- Number: US 12,763,544 B2
- Document ID: US12763544B2
- Status: Granted
- Kind: B2
- Application number: 18/394,319
- Filed: 2023-12-22
- Published: 2025-06-26
- Granted: 2026-10-13
- Earliest claimed: 2023-12-22
- Assignees: Rosemount Aerospace Inc.
- Applicants: Rosemount Aerospace Inc.
- Inventors: Gary E. Halama
- Web page: https://patentgrep.com/patent/US12763544B2

## CPC

- H01S 3/1109: Active mode locking
- G01N 21/255: {Details, e.g. use of specially adapted sources, lighting or optical systems}
- G01N 21/538: {for determining atmospheric attenuation and visibility}
- H01S 3/0071: {Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction}
- H01S 3/0085: {Modulating the output, i.e. the laser beam is modulated outside the laser cavity}
- H01S 3/10015: {by monitoring or controlling, e.g. attenuating, the input signal}
- H01S 3/10023: {by functional association of additional optical elements, e.g. filters, gratings, reflectors}
- H01S 3/10092: {Coherent seed, e.g. injection locking}
- H01S 3/2308: {Amplifier arrangements, e.g. MOPA}
- G01N 2021/392: {Measuring reradiation, e.g. fluorescence, backscatter}
- G01N 2201/06113: Coherent sources; lasers
- 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
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Apparatus and associated methods relate to mode matching a plurality of optical beams to a corresponding plurality of optical power amplifiers. The mode-matched plurality of beams is generated by mode matching a single laser beam and then splitting the mode-matched beam into the plurality of beam-split portions. Each of the plurality of beam-split portions is then guided to a corresponding one of a plurality of optical power amplifiers that amplifies the beam-split portion guided thereto. Optical path lengths between the mode-matching optics and the plurality of optical power amplifiers are created to be substantially equal to one another thereby enabling optical mode matching of the mode-matched optical beam to each of the plurality of optical power amplifiers.

## Claims

### Claim 1

A system for measuring metrics of an atmosphere, the system including:
a laser configured to generate a laser beam;
mode-matching optics configured to receive the laser beam generated by the laser and to generate a mode-matched optical beam therefrom;
a plurality of beam splitters configured to split the mode-matched optical beam into a plurality of beam-split portions,
wherein each of the plurality of beam splitters includes:
first and second right-triangular isosceles prisms sandwiching a beam-splitting layer between hypotenuse faces of the first and second right-triangular isosceles prisms,
wherein each of the plurality of beam-split portions of the mode-matched optical beams has an amplitude that is substantially equal in amplitude with others of the plurality of beam-split portions of the mode-matched optical beams; and
a plurality of optical power amplifiers, each configured to receive and amplify a corresponding one of the plurality of beam-split portions of the mode-matched optical beam, optical path lengths between the mode-matching optics and the plurality of optical power amplifiers being substantially equal to one another thereby enabling optical mode matching of the mode-matched optical beam to each of the plurality of optical power amplifiers;
a plurality of optical projectors configured to project a plurality of projected beams into an atmosphere, each of the plurality of optical projectors configured to project a corresponding one of the plurality of amplified beams thereby projecting a corresponding one of the plurality of projected beams;
a plurality of optical receivers configured to receive a plurality of received beam-split portions of the plurality of projected beams backscattered by the atmosphere, each of the plurality of optical receivers aligned so as to receive a corresponding one of the plurality of received beam-split portions of the plurality of projected beams backscattered by the atmosphere; and
an air-data calculator configured to calculate metrics of air data based on the plurality of received beam-split portions.

### Claim 2

A system for optical mode matching a plurality of optical beams to a corresponding plurality of optical power amplifiers, the system including:
a laser configured to generate a laser beam;
mode-matching optics configured to receive the laser beam generated by the laser and to generate a mode-matched optical beam therefrom;
a plurality of beam splitters configured to split the mode-matched optical beam into a plurality of beam-split portions,
wherein each of the plurality of beam splitters includes:
first and second right-triangular isosceles prisms sandwiching a beam-splitting layer between hypotenuse faces of the first and second right-triangular isosceles prisms,
wherein each of the plurality of beam-split portions of the mode-matched optical beams has an amplitude that is substantially equal in amplitude with others of the plurality of beam-split portions of the mode-matched optical beams; and
a plurality of optical power amplifiers, each configured to receive and amplify a corresponding one of the plurality of beam-split portions of the mode-matched optical beam, optical path lengths between the mode-matching optics and the plurality of optical power amplifiers being substantially equal to one another thereby enabling optical mode matching of the mode-matched optical beam to each of the plurality of optical power amplifiers.

### Claim 3 (depends on 2)

The system of claim 2, wherein the plurality of beam-split portions of the mode-matched optical beam includes first, second, third, and fourth beam-split portions of the mode-matched optical beam.

### Claim 4 (depends on 3)

The system of claim 3, wherein the plurality of beam splitters includes:
a first beam splitter configured to receive the mode-matched optical beam and to split the mode-match optical beam into first and second intermediate beams that are substantially equal in amplitude with one another;
a second optical splitter configured to receive the first intermediate beam and to split the first intermediate beam into the first and second beam-split portions that are substantially equal in amplitude with one another; and
a third optical splitter configured to receive the second intermediate beam and to split the second intermediate beam into the third and fourth beam-split portions that are substantially equal in amplitude with one another.

### Claim 5 (depends on 4)

The system of claim 4, further comprising:
first and second beam-guide prisms configured to guide the first and second intermediate beams from the first beam splitter to the second and third beam splitters respectively.

### Claim 6 (depends on 5)

The system of claim 5, wherein the first and second beam-guide prisms have indices of refraction that is substantially equal to indices of refraction of the first and second right-triangular isosceles prisms of each of the first, second, and third beam splitters.

### Claim 7 (depends on 6)

The system of claim 6, wherein the plurality of optical power amplifiers includes:
first, second, third, and fourth optical power amplifiers configured to receive and amplify the first, second, third, and fourth beam-split portions of the mode-matched optical beam, respectively.

### Claim 8 (depends on 7)

The system of claim 7, further comprising:
third and fourth beam-guide prisms configured to guide the first and second beam-split portions from the second beam splitter to the first and second optical power amplifiers; and
fifth and sixth beam-guide prisms configured to guide the third and fourth beam-split portions from the third beam splitter to the third and fourth optical power amplifiers.

### Claim 9 (depends on 8)

The system of claim 8, wherein the third, fourth, fifth and sixth beam-guide prisms have indices of refraction that is substantially equal to indices of refraction of the first and second right-triangular isosceles prisms of each of the first, second, and third beam splitters.

### Claim 10 (depends on 9)

The system of claim 9, wherein the index of refraction is substantially constant throughout the optical paths from the first beam splitter to the first, second, third, and fourth optical power amplifiers.

### Claim 11

A method for optical mode matching a plurality of optical beams to a corresponding plurality of optical power amplifiers, the system including:
generating, via a laser, a laser beam;
generating, via mode-matching optics, a mode-matched optical beam from the laser beam;
splitting, via a plurality of beam splitters, the mode-matched optical beam into a plurality of beam-split portions,
wherein splitting the mode-matched optical beam includes:
splitting, via first, second, and third beam splitters, the mode-matched optical beam into first, second, third, and fourth beam-split portions,
wherein splitting the mode-matched optical beam into a plurality of beam-split portions is done in such manner as to make amplitudes of the plurality of beam-split portions substantially equal to one another,
wherein splitting the mode-matched optical beam includes:
splitting, via a first beam splitter, the mode-matched optical beam into first and second intermediate beams that are substantially equal in amplitude with one another;
splitting, via a second optical splitter, the first intermediate beam into the first and second beam-split portions that are substantially equal in amplitude with one another; and
splitting, via a third optical splitter, the second intermediate beam into the third and fourth beam-split portions that are substantially equal in amplitude with one another;
guiding, via first and second beam-guide prisms, the first and second intermediate beams from the first beam splitter to the second and third beam splitters respectively;
amplifying, via each of a plurality of optical power amplifiers, a corresponding one of the plurality of beam-split portions of the mode-matched optical beam; and
configuring the plurality of splitters and the plurality of optical power amplifiers so as to make substantially equal to one another optical path lengths between the mode-matching optics and the plurality of optical power amplifiers, thereby enabling optical mode matching of the mode-matched optical beam to each of the plurality of optical power amplifiers.

### Claim 12 (depends on 11)

The method of claim 11, wherein the first and second beam-guide prisms have indices of refraction that is substantially equal to indices of refraction of the first and second right-triangular isosceles prisms of each of the first, second, and third beam splitters.

### Claim 13 (depends on 12)

The method of claim 12, wherein the plurality of optical power amplifiers includes:
amplifying, via first, second, third, and fourth optical power amplifiers, the first, second, third, and fourth beam-split portions of the mode-matched optical beam, respectively.

### Claim 14 (depends on 13)

The method of claim 13, further comprising:
guiding, via third and fourth beam-guide prisms, the first and second beam-split portions from the second beam splitter to the first and second optical power amplifiers; and
guiding, via fifth and sixth beam-guide prisms, the third and fourth beam-split portions from the third beam splitter to the third and fourth optical power amplifiers.