# US 11,114,810 B2 · Laser device

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- Number: US 11,114,810 B2
- Document ID: US11114810B2
- Status: Granted
- Kind: B2
- Application number: 16/424,709
- Filed: 2019-05-29
- Published: 2019-12-05
- Granted: 2021-09-07
- Earliest claimed: 2018-05-30
- Assignees: Hamamatsu Photonics K.K.
- Applicants: Hamamatsu Photonics K.K.
- Inventors: Koichi Iyama; Yasuki Takeuchi; Yuma Hatano; Takaaki Morita; Takuto Iguchi; Yoshinori Kato; Takashi Sekine
- Web page: https://patentgrep.com/patent/US11114810B2

## CPC

- H01S 3/0404: {Air- or gas cooling, e.g. by dry nitrogen}
- H01S 3/0407: {Liquid cooling, e.g. by water}
- H01S 3/025: {of solid state lasers, e.g. housings or mountings}
- H01S 3/0405: {Conductive cooling, e.g. by heat sinks or thermo-electric elements}
- H01S 3/042: for solid state lasers {(H01S3/0401 takes precedence)}
- H01S 3/0621: {Coatings on the end-faces, e.g. input/output surfaces of the laser light}
- H01S 3/07: consisting of a plurality of parts, e.g. segments (H01S3/067 takes precedence)
- H01S 3/08059: {Constructional details of the reflector, e.g. shape (mirrors in general G02B5/08; mountings for mirrors G02B7/18)}
- H01S 3/10007: {in optical amplifiers}
- H01S 3/10092: {Coherent seed, e.g. injection locking}
- H01S 3/2316: {Cascaded amplifiers}
- H01S 3/0604: {in the form of a plate or disc}
- H01S 3/1618: {ytterbium}
- H01S 3/1643: {YAG}
- H01S 3/2333: {Double-pass amplifiers}
- H01S 2301/02: ASE (amplified spontaneous emission), noise; Reduction thereof
- 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

A laser device includes a first laser medium and a second laser medium that have a first surface and a second surface opposite to the first surface, and receive input of excitation light and seed light from the first surface side to amplify the seed light, a holder that holds the first laser medium and the second laser medium; and a pair of cooling units that cool the first laser medium and the second laser medium according to change in volume of a refrigerant.

## Claims

### Claim 1

A laser device comprising:
a first laser medium and a second laser medium that have a first surface and a second surface opposite to the first surface, and receive input of excitation light and seed light from the first surface side to amplify the seed light;
a holder that holds the first laser medium and the second laser medium; and
a pair of cooling units that cool the first laser medium and the second laser medium according to change in volume of a refrigerant,
wherein a first mirror that reflects at least the seed light is provided on the second surface,
the first laser medium and the second laser medium are disposed at relative positions in which the seed light reflected by the first mirror of the first laser medium is further reflected by the first mirror of the second laser medium,
the holder integrally holds the first laser medium and the second laser medium so that the relative position is maintained,
the first laser medium and the second laser medium are disposed such that the first mirror of the first laser medium and the first mirror of the second laser medium are parallel to each other,
the pair of cooling units include a refrigerator that cools the first laser medium and the second laser medium according to compression and expansion of the refrigerant, and
the first laser medium and the second laser medium are thermally connected to the pair of cooling units via a respective flexible heat conductive member.

### Claim 2 (depends on 1)

The laser device according to claim 1, comprising:
a second mirror that reflects the seed light reflected by the first mirror of the second laser medium so that the seed light is incident on the first mirror of the second laser medium at an incidence angle equal to a reflection angle of the seed light on the first mirror of the second laser medium.

### Claim 3 (depends on 1)

The laser device according to claim 1, wherein the holder includes
a placement portion in which the first laser medium and the second laser medium are placed on a placement surface that is along an optical path of the seed light; and
a holding portion that is provided integrally with the placement portion to protrude from the placement surface, and holds the first laser medium and the second laser medium so that the relative position is maintained.

### Claim 4 (depends on 1)

The laser device according to claim 1, wherein the refrigerator cools the first laser medium and the second laser medium according to periodic compression and expansion of the refrigerant.

### Claim 5 (depends on 1)

The laser device according to claim 1, wherein the respective flexible heat conductive member is a mesh wire.

### Claim 6 (depends on 1)

The laser device according to claim 1, wherein the respective flexible heat conductive member has one end attached to a cold head of a respective cooling unit of the pair of cooling units and another end attached to a respective heat sink provided on the respective second surface of the first laser medium and the second laser medium.