LASER MODULE

• US 20190319431A1
• Filed: 11/16/2017
• Published: 10/17/2019
• Est. Priority Date: 11/16/2016
• Status: Abandoned Application

• Current Assignee: Fujikura Limited
• Original Assignee: Fujikura Limited
• Inventors: Katagiri, Ken
• Application Number:
  US16/347,646
• Publication Number:
  US 20190319431A1
• Time in Patent Office: Days
• CPC Class Codes: G02B 6/4207 with optical elements reducing the sensitivity to optical feedback anti-reflection devices specially adapted for lasers, see H01S3/0064
• CPC Class Codes: G02B 6/4296 coupling with sources of high radiant energy, e.g. high power lasers, high temperature light sources
• CPC Class Codes: H01S 5/02251 using optical fibres
• CPC Class Codes: H01S 5/02253 using lenses
• CPC Class Codes: 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
• CPC Class Codes: H01S 5/0239 Combinations of electrical or optical elements
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4031 Edge-emitting structures

Abstract

An embodiment of the present invention provides a laser module having a longer average device life as compared to a conventional laser module. A laser module (1) includes: a plurality of laser diodes (LD1 to LD6) emitting laser beams; and an optical fiber (OF), the laser beams being caused to enter the optical fiber (OF), the laser diodes (LD1 to LD6) being arranged such that among light beams constituting return light emitted from the optical fiber (OF), a paraxial beam does not meet active layers of the laser diodes (LDi) at respective exit end surfaces of the laser diodes (LDi), the paraxial beam having been emitted from the optical fiber (OF) at an emission angle θ of not more than θ1 which is given by the following Formula (A):

$\left[\mathrm{Math}.1\right]$ $\begin{array}{cc}{\theta }_1=\frac{\mathrm{Arcsin}\left(\mathrm{NA}\right)}{3}\sqrt{2\ln 2},& \left(A\right)\end{array}$

where NA is a numerical aperture of the optical fiber.

Claims

1. A laser module comprising:

a plurality of laser diodes emitting laser beams; and

an optical fiber,

the laser beams being caused to enter the optical fiber,

the laser diodes being arranged such that among light beams constituting return light emitted from the optical fiber, a paraxial beam does not meet active layers of the laser diodes at respective exit end surfaces of the laser diodes, the paraxial beam having been emitted from the optical fiber at an emission angle θ

of not more than θ

1 which is given by the following Formula (A);

2. The laser module as set forth in claim 1, wherein:

the laser diodes are spatially clustered.

3. The laser module as set forth in claim 1, wherein:

the laser diodes are arranged such that (a) the respective exit end surfaces of the laser diodes are provided on a certain line segment or a certain circular arc and (b) a distance between adjacent laser diodes which belong to different clusters is larger than a distance between adjacent laser diodes which belong to one cluster.

4. The laser module as set forth in claim 3, wherein:

the laser diodes are 2M laser diodes, where M is a natural number of not less than 2; and

the 2M laser diodes are arranged such that the respective exit end surfaces of the laser diodes are provided at 2M points x₁, x₂, . . . , x_M, and x<sub>N−

M+1</sub>, x<sub>N−

M+2</sub>, . . . , x_N selected from among N points x₁, x₂, . . . , x_N, where N is a natural number of not less than 2M+1, the N points x₁, x₂, . . . , x_N being provided at equal intervals on the certain line segment or the certain circular arc and arranged such that a relation of optical path lengths L_j from respective points x_j to an entrance end surface of the optical fiber is L₁>

L₂>

. . . >

L_N.

5. The laser module as set forth in claim 3, wherein:

the laser diodes are 2M−

1 laser diodes, where M is a natural number of not less than 2; and

the 2M−

1 laser diodes are arranged such that the respective exit end surfaces of the laser diodes are provided at 2M−

1 points x₁, x₂, . . . , x_M, and x<sub>N−

M+2</sub>, x<sub>N−

m+3</sub>, . . . , x_N selected from among N points x₁, x₂, . . . , x_N, where N is a natural number of not less than 2M+1, the N points x₁, x₂, . . . , x_N being provided at equal intervals on the certain line segment or the certain circular arc and arranged such that a relation of optical path lengths L_j from respective points x_j to an entrance end surface of the optical fiber is L₁>

L₂>

. . . >

L_N.

6. A laser module comprising:

2M−

1 laser diodes emitting laser beams, where M is a natural number of not less than 2; and

an optical fiber,

the laser beams being caused to enter the optical fiber,

the 2M−

1 laser diodes being spatially clustered such that among light beams constituting return light emitted from the optical fiber, a light beam on an optical axis does not meet active layers of the 2M−

1 laser diodes at respective exit end surfaces of the 2M−

1 laser diodes, the light beam on the optical axis being emitted at an emission angle of 0°

,

the 2M−

1 laser diodes being arranged such that the respective exit end surfaces of the 2M−

1 laser diodes are provided at 2M−

1 points x₁, x₂, . . . , x_M, and x<sub>N−

M+2</sub>, x<sub>N−

M+3</sub>, . . . , x_N selected from among N points x₁, x₂, . . . , x_N, where N is a natural number of not less than 2M+1, the N points x₁, x₂, . . . , x_N being provided at equal intervals on a certain line segment or a certain circular arc and arranged such that a relation of optical path lengths L_j from respective points x_j to an entrance end surface of the optical fiber is L₁>

L₂>

. . . >

L_N.