# US 9,766,466 B2 · Semiconductor laser module

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- Number: US 9,766,466 B2
- Document ID: US9766466B2
- Status: Granted
- Kind: B2
- Application number: 14/894,015
- Filed: 2014-06-11
- Published: 2016-04-14
- Granted: 2017-09-19
- Earliest claimed: 2013-06-12
- Assignees: Pantec Engineering AG
- Applicants: Pantec Engineering AG
- Inventors: Arne Heinrich; Clemens Hagen
- Web page: https://patentgrep.com/patent/US9766466B2

## CPC

- G02B 27/0955: {Lenses (lenses per se G02B3/00)}
- G02B 19/0014: {at least one surface having optical power}
- G02B 19/0052: {the light source comprising a laser diode (coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005)}
- G02B 27/0966: {Cylindrical lenses (cylindrical lenses per se G02B3/06)}
- G02B 27/0994: {Fibers, light pipes (optical fibers per se G02B6/02)}
- H01S 5/005: {Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping (H01S5/026, H01S5/18388 take precedence)}
- H01S 5/1064: {varying width along the optical axis}
- H01S 5/22: having a ridge or stripe structure
- H01S 5/405: {Two-dimensional arrays}
- H01S 5/50: Amplifier structures not provided for in groups H01S5/02 - H01S5/30
- 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

A semiconductor laser module (10) comprises a tapered laser diode (12) and/or a tapered amplifier diode equipped with beam shaping optics (14). The tapered laser diode and/or the tapered amplifier diode includes an emission facet (16) for emitting a laser beam (18) along a beam axis (24). The beam-shaping optics comprise a plano-convex cylindrical lens oriented so as to change divergence of the beam in the fast axis direction, the plano-convex spherical cylindrical lens having a planar surface (26) arranged facing the facet and a circular cylindrical surface (22) facing away from the facet.

## Claims

### Claim 1

A semiconductor laser module, comprising at least one of a tapered laser diode and a tapered amplifier diode, including an emission facet for emitting a laser beam along a beam axis, said laser beam having a beam quality factor in fast axis direction, hereinafter denoted Mf2, and a beam quality factor in slow axis direction, hereinafter denoted Ms2; and
beam shaping optics;
wherein said beam-shaping optics comprise a plano-convex cylindrical lens oriented so as to change divergence of said beam in fast axis direction, said plano-convex cylindrical lens having a planar surface arranged facing said facet a circular cylindrical surface facing away from said facet and a refractive index, hereinafter denoted n, chosen such that the condition
93
⁢
%
·
sin
⁢
⁢
u
f
/
sin
(
u
s
·
M
f
2
M
s
2
)
≤
n
≤
107
⁢
%
·
sin
⁢
⁢
u
f
/
sin
(
u
s
·
M
f
2
M
s
2
)
,
where uf denotes the uncorrected 1/e2 fast axis divergence half-angle of said laser beam and us denotes the uncorrected 1/e2 slow axis divergence half-angle of said laser beam, is satisfied.

### Claim 2 (depends on 1)

The semiconductor laser module as claimed in claim 1, wherein said plano-convex cylindrical lens is configured and positioned such that said circular cylindrical surface intersects said beam axis at an axial position where the ratio of the slow axis beam diameter of said laser beam to the fast axis beam diameter of said laser beam amounts to a value in the range from 0.87·Ms2/Mf2 to 1.15·Ms2/Mf2.

### Claim 3 (depends on 1)

The semiconductor laser module as claimed in claim 1 wherein said planar surface of said plano-convex cylindrical lens is arranged at a distance from said facet comprised in the range from 50 μm to 1 mm.

### Claim 4 (depends on 1)

The semiconductor laser module as claimed in claim 1, wherein a radius of curvature of said circular cylindrical surface of said plano-convex cylindrical lens is chosen such that said divergence of said beam in fast axis direction is reduced to match a product of a divergence of said beam in slow axis direction and the ratio Mf2/Ms2.

### Claim 5 (depends on 1)

The semiconductor laser module as claimed in claim 1, wherein said laser beam emitted at said facet has an uncorrected fast axis divergence half-angle comprised in the range from 12-23° and an uncorrected slow axis divergence half-angle comprised in the range from 6-13°.

### Claim 6 (depends on 1)

The semiconductor laser module as claimed in claim 1, wherein said circular cylindrical surface of said plano-convex cylindrical lens has a radius of curvature satisfying the condition:
87
⁢
%
·
d
f
2
⁢
(
n
+
1
)
⁢
tan
(
u
s
·
M
f
2
M
s
2
)
≤
r
≤
115
⁢
%
·
d
f
2
⁢
(
n
+
1
)
⁢
tan
(
u
s
·
M
f
2
M
s
2
)
,
where r denotes said radius of curvature, df denotes the beam diameter in fast axis direction of said laser beam at the axial position in which said circular cylindrical surface intersects said beam axis, n denotes said refractive index and us denotes the uncorrected slow axis divergence half-angle of said laser beam.

### Claim 7 (depends on 1)

The semiconductor laser module as claimed in claim 1, wherein said facet has a width in slow axis direction comprised in the range from 150 μm to 2 mm and a height in fast axis direction comprised in the range from 0.1 μm to 5μm.

### Claim 8 (depends on 1)

The semiconductor laser module as claimed in claim 1, wherein said plano-convex cylindrical lens has a focal length comprised in the range from 1 mm to 10 mm.

### Claim 9 (depends on 1)

A semiconductor laser array comprising a stack of a plurality of semiconductor laser modules as claimed in claim 1.

### Claim 10 (depends on 9)

The semiconductor laser array as claimed in claim 9, wherein said semiconductor laser modules are substantially identical.

### Claim 11

A semiconductor laser module, comprising at least one of a tapered laser diode and a tapered amplifier diode, including an emission facet for emitting a laser beam along a beam axis, said laser beam having a beam quality factor in fast axis direction, hereinafter denoted Mf2, and a beam quality factor in slow axis direction, hereinafter denoted Ms2; and
beam shaping optics;
wherein said beam-shaping optics comprise a plano-convex cylindrical lens positioned directly in front of the emission facet and oriented so as to reduce divergence of said beam in fast axis direction, said plano-convex cylindrical lens having a planar surface arranged facing said facet, and a circular cylindrical surface facing away from said facet, and
wherein circular cylindrical surface has a radius of curvature chosen such that said divergence of said beam in fast axis direction is reduced to match the product of divergence of said beam in slow axis direction and the ratio Mf2/Ms2 wherein the plano-convex cylindrical lens has a refractive index n chosen such that the condition
93
⁢
%
·
sin
⁢
⁢
u
f
/
sin
⁢
⁢
(
u
s
·
M
f
2
M
s
2
)
≤
n
≤
107
⁢
%
·
sin
⁢
⁢
u
f
/
sin
⁢
⁢
(
u
s
·
M
f
2
M
s
2
)
,
where ur denotes the uncorrected 1/e2 fast axis divergence half-angle of said laser beam us denotes the uncorrected 1/e2 slow axis divergence half-angle of said laser beam, is satisfied.

### Claim 12 (depends on 11)

The semiconductor laser module as claimed in claim 11, wherein said plano-convex cylindrical lens is configured and positioned such that said circular cylindrical surface intersects said beam axis at an axial position where the ratio of the slow axis beam diameter of said laser beam to the fast axis beam diameter of said laser beam amounts to a value in the range from 0.87·Ms2/Mf2 to 1.15·Ms2/Mf2.

### Claim 13 (depends on 11)

The semiconductor laser module as claimed in claim 11, wherein said circular cylindrical surface of said plano-convex cylindrical lens has a radius of curvature r satisfying the condition:
87
⁢
%
·
d
f
2
⁢
(
n
+
1
)
⁢
tan
⁡
(
u
s
⁢
M
f
2
M
s
2
)
≤
r
≤
115
⁢
%
·
d
f
2
⁢
(
n
+
1
)
⁢
tan
⁡
(
u
s
⁢
M
f
2
M
s
2
)
,
where df denotes the beam diameter in fast axis direction of said laser beam at the axial position in which said circular cylindrical surface intersects said beam axis, n denotes said refractive index and us denotes the uncorrected slow axis divergence half-angle of said laser beam.

### Claim 14

A semiconductor laser module, comprising at least one of a tapered laser diode and a tapered amplifier diode, including an emission facet for emitting a laser beam along a beam axis, said laser beam having a beam quality factor in fast axis direction, hereinafter denoted Mf2, and a beam quality factor in slow axis direction, hereinafter denoted Ms2, said laser beam having a first virtual source from which said laser beam appears to diverge in fast axis direction and a second virtual source from which said laser beam appears to diverge in slow axis direction, said second virtual source being located farther away from the emission facet than said first virtual source; and
beam shaping optics;
wherein said beam-shaping optics comprise a plano-convex cylindrical lens positioned directly in front of the emission facet and oriented so as to change divergence of said beam in fast axis direction, said plano-convex cylindrical lens having a planar surface arranged facing said facet, a circular cylindrical surface facing away from said facet; and
wherein the plano-convex cylindrical lens is configured and arranged to satisfy the aplanatic condition in such a way that a virtual image of the first virtual source by the plano-convex cylindrical lens substantially coincides with the second virtual source wherein the plano-convex cylindrical lens has a refractive index n chosen such that the condition
93
⁢
%
·
sin
⁢
⁢
u
f
/
sin
⁢
⁢
(
u
s
·
M
f
2
M
s
2
)
≤
n
≤
107
⁢
%
·
sin
⁢
⁢
u
f
/
sin
⁢
⁢
(
u
s
·
M
f
2
M
s
2
)
,
where ur denotes the uncorrected 1/e2 fast axis divergence half-angle of said laser beam us denotes the uncorrected 1/e2 slow axis divergence half-angle of said laser beam, is satisfied.

### Claim 15 (depends on 14)

The semiconductor laser module as claimed in claim 14, wherein said plano-convex cylindrical lens is configured and positioned such that said circular cylindrical surface intersects said beam axis at an axial position where the ratio of the slow axis beam diameter of said laser beam to the fast axis beam diameter of said laser beam amounts to a value in the range from 0.87·Ms2/Mr2 to 1.15·Ms2/Mf2.

### Claim 16 (depends on 14)

The semiconductor laser module as claimed in claim 14, wherein said circular cylindrical surface of said plano-convex cylindrical lens has a radius of curvature r satisfying the condition:
87
⁢
%
·
d
f
2
⁢
(
n
+
1
)
⁢
tan
⁡
(
u
s
⁢
M
f
2
M
s
2
)
≤
r
≤
115
⁢
%
·
d
f
2
⁢
(
n
+
1
)
⁢
tan
⁡
(
u
s
⁢
M
f
2
M
s
2
)
,
where df denotes the beam diameter in fast axis direction of said laser beam at the axial position in which said circular cylindrical surface intersects said beam axis, n denotes said refractive index and us denotes the uncorrected slow axis divergence half-angle of said laser beam.