# US 5,349,600 A · Solid state laser

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- Number: US 5,349,600 A
- Document ID: US5349600A
- Status: Granted
- Kind: A
- Application number: 08/116,323
- Filed: 1993-09-03
- Granted: 1994-09-20
- Earliest claimed: 1992-09-21
- Assignees: Kokusai Denshin Denwa Kabushiki Kaisha
- Inventors: Osamu Shinbori; Yoshinori Mimura; Yukio Noda; Tetsuya Nakai
- Web page: https://patentgrep.com/patent/US5349600A

## CPC

- H01S 3/0941: of a laser diode
- H01S 3/0602: {Crystal lasers or glass lasers (H01S3/063 takes precedence)}
- H01S 3/0612: {Non-homogeneous structure (H01S3/07 takes precedence)}
- H01S 3/0625: {Coatings on surfaces other than the end-faces}
- H01S 3/067: Fibre lasers
- H01S 3/094084: {with pump light recycling, i.e. with reinjection of the unused pump light, e.g. by reflectors or circulators}
- 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 high-output, single fundamental transverse mode solid state laser is disclosed which uses a semiconductor laser array as an excitation light source. The solid state laser comprises: a laser element which includes a core containing an element added as a laser medium, a cladding containing no such laser medium element, and reflecting mirrors coated over the cladding surface for repeatedly reflecting incident excitation light so that it may repeatedly pass through the core; an excitation light source formed by semi-conductor laser or light emitting diode array; means for guiding the excitation light from the excitation light source to one side of the laser element for incidence thereto; and a resonator for the oscillation of the solid state laser.

## Claims

### Claim 1

A high-output solid state laser of single functional mode of laser light comprising,
a high efficiency cylindrical laser glass rod core containing an element added as a laser medium and a cylindrical glass cladding disposed circumferentially of said rod core and longitudinally thereof concentrically therewith;
said glass cladding being free of an element acting as a laser medium and defining a narrow slit along a length thereof as an entrance window for excitation light to pass therethrough for incidence on said rod core along an optical axis thereof;
a source of said excitation light and means for focusing the excitation light on the surface of said glass cladding;
high incident light reflecting mirror surfaces formed on said glass cladding disposed for defining said narrow slit and for reflecting continuously excitation light passing through said rod core back accurately through the optical axis of the core so that incident light is accurately repeatedly reflected to the optical axis of the rod core for high efficiency absorption of the incident excitation light; and
an optical resonator for developing laser oscillations along the optical axis of said rod core.

### Claim 2 (depends on 1)

A solid state laser according to claim 1, in which said optical resonator comprises a first reflecting mirror having a concave reflector surface and a second reflecting mirror having a flat reflector surface spaced coaxially from each other.

### Claim 3 (depends on 2)

A solid state laser according to claim 2, in which said first and second reflecting mirror of said optical resonator are formed on opposite ends of said cladding.

### Claim 4 (depends on 1)

A solid state laser according to claim 1, in which said incident light reflecting mirror surfaces are disposed circumferentially and axially of said slit, and said slit is disposed in the center of the incident light reflecting mirror surfaces to reduce loss of reflected excitation light through said slit.

### Claim 5 (depends on 1)

A solid state laser according to claim 1, in which said rod core and said cladding are made of fluoride glass, and surfaces of the cladding not constituting said incident light reflecting mirror surfaces are coated with a moisture-resistant film of low reflectivity.

### Claim 6 (depends on 5)

A solid state laser according to claim 5, capable of oscillation in the infrared wavelength regions in the range of absorption bands of low molecular weight gaseous materials such as carbon monoxide, carbon dioxide, nitrogen oxides and methane gas for spectral analysis of said materials.