CN115566535B

CN115566535B - External cavity semiconductor laser

Info

Publication number: CN115566535B
Application number: CN202211552862.6A
Authority: CN
Inventors: 郭渭荣; 时敏; 王宝华; 李娟�; 董晓培; 郭方君玥; 张艳聪; 房谦; 陈晓华
Original assignee: BWT Beijing Ltd
Current assignee: BWT Beijing Ltd
Priority date: 2022-12-06
Filing date: 2022-12-06
Publication date: 2023-05-02
Anticipated expiration: 2042-12-06
Also published as: CN115566535A

Abstract

The invention provides an external cavity semiconductor laser, which comprises an external cavity, wherein the external cavity comprises a laser single tube, a filter and an external cavity mirror; the laser monotube comprises a first laser monotube and a second laser monotube, and the first laser monotube emits light beams in a first direction; the second laser single tube emits light beams in a second direction; the filter plate comprises a first filter plate and a second filter plate, and the second filter plate filters out the light beams emitted by the second laser single tube; the first filter filters out the light beam emitted by the first laser single tube, reflects the light beam of the second wave band and then emits the light beam of the first wave band to the external cavity mirror in the first direction, wherein the first wave band is separated from the second wave band; the light beams emitted by the first laser single tube and the second laser single tube oscillate back and forth in the outer cavity, perform wavelength beam combination and output laser through the outer cavity mirror. The invention can obtain high-power laser beams, so that the total beams approach to the beam parameter product of a single laser tube, thereby maintaining the beam quality of laser and improving the brightness of the laser beams.

Description

External cavity semiconductor laser

Technical Field

The invention relates to the technical field of lasers, in particular to an external cavity semiconductor laser.

Background

Since the advent of semiconductor lasers, the semiconductor lasers have been increasingly used in many fields such as precision measurement, material processing, communication, etc. because of their advantages of high conversion efficiency, small size, light weight, high reliability, direct modulation, and strong integration with other semiconductor devices.

One solution to increase the high power and brightness required of semiconductor lasers is to spatially combine beams. Referring to fig. 1, in the prior art, a bottom plate 6 with a stepped structure is required for spatial beam combination, so that light beams output by a plurality of laser single tubes 1 sequentially pass through a fast axis collimating lens 3 and a slow axis collimating lens 4 and are diverted through a total reflection mirror 5. The laser single tubes are sequentially arranged in space 1 to splice a larger light spot.

In carrying out the invention, the inventors have found that at least the following problems exist in the prior art: the prior art can arrange the light beams of a plurality of laser single tubes side by side to one, although the light beams with larger power can be generated, the total light spot after arrangement is larger than the light spot of a single laser single tube, the light beam parameter product (the product of the waist spot size and the far field divergence angle) is correspondingly increased, and the brightness is defined as the energy radiated by a light source with unit area in unit time towards the light beam parameter product in the normal direction of the light source, so that the brightness improving effect of the prior art is poor, and the size of the laser is larger.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems in the related art to a certain extent.

Therefore, the invention aims to provide an external cavity semiconductor laser with better brightness improving effect.

In order to achieve the above purpose, the invention provides an external cavity semiconductor laser, which comprises an external cavity, wherein the external cavity comprises a laser single tube, a filter and an external cavity mirror;

the laser single tube comprises a first laser single tube and a second laser single tube, and the first laser single tube is used for emitting light beams in a first direction; the second laser single tube is used for emitting light beams in a second direction;

the filter comprises a first filter and a second filter, and the second filter is used for filtering out the light beams emitted by the second laser single tube into light beams of a second wave band; the first filter is used for filtering out the light beam of the first wave band emitted by the first laser single tube, reflecting the light beam of the second wave band and then directing the light beam of the second wave band to the external cavity mirror in a first direction, wherein the first wave band is separated from the second wave band;

and the light beams emitted by the first laser single tube and the second laser single tube oscillate back and forth in the outer cavity to perform wavelength beam combination, and laser is output through the outer cavity mirror.

According to the external cavity semiconductor laser provided by the embodiment of the invention, the first laser single tube, the second laser single tube, the filter and the external cavity mirror are utilized to form the external cavity, and the laser single tube uses the semiconductor material as a gain medium to amplify light. According to the embodiment of the invention, the two laser single tubes are utilized for wavelength beam combination, so that high-power laser beams are obtained, the power of the two laser single tubes is integrated, and meanwhile, the total beam is kept close to the beam parameter product of one laser single tube, so that the beam quality of laser is kept, and the brightness of the laser beams is improved. The laser provided by the embodiment of the invention has no bottom plate with a step structure, and can reduce the volume of the laser.

According to one embodiment of the invention, the filter is a bandpass filter.

According to one embodiment of the invention, the laser monotube is an edge emitting laser.

According to one embodiment of the invention, the band-pass filter has a plurality of film layers with alternately high-refractive index and low-refractive index films, and the band-pass filter is used for transmitting light beams with different wave bands according to different incidence angles of the incident light beams of the laser single tube.

According to one embodiment of the invention, a collimating lens is arranged in front of a first end of the laser single tube, the first end of the laser single tube is a transmission part, a second end of the laser single tube is a reflection part, and a junction area is arranged between the first end and the second end of the laser single tube;

the transmission part is used for making the light beam incident and emergent; the reflecting part is used for reflecting the light beam, and the junction area is used for carrying out oscillation amplification on the light beam.

According to one embodiment of the present invention, the external cavity mirror is a partially transparent mirror, and the partially transparent mirror is used for reflecting a part of a light beam emitted from the single tube of the laser, and transmitting a part of the light beam to output laser.

According to one embodiment of the invention, the collimating lens is a fast axis collimating lens.

According to one embodiment of the present invention, the transmissive portion is coated with an antireflection film, and the reflective portion is coated with a total reflection film.

According to one embodiment of the invention, the number of the laser single tubes is N, the number of the band-pass filters is N, and the band-pass filters have N pass bands;

the kth laser monotube is used for emitting light beams in the kth direction;

a kth band-pass filter is arranged in front of the first end of the kth laser single tube; the kth band-pass filter is used for filtering out the light beam emitted by the kth laser single tube, reflecting the light beam from the kth+1th to the nth band, and directing the light beam to the kth-1th band-pass filter in the kth direction or the external cavity mirror when k=1, wherein N is a positive integer greater than 2, and k is a positive integer less than or equal to N.

According to one embodiment of the invention, the planes of the bottoms of the N single laser tubes are coplanar.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. Wherein:

fig. 1 is a schematic diagram of a prior art laser with spatial beam combining.

Fig. 2 is a schematic structural diagram of an external cavity semiconductor laser according to an embodiment of the present invention.

Fig. 3 is a graph showing a refractive index profile of a film layer of a band-pass filter of an external cavity semiconductor laser according to an embodiment of the present invention.

Fig. 4 is a graph showing transmittance of a band-pass filter of an external cavity semiconductor laser according to an embodiment of the present invention for different wavelengths as a function of incident angle.

Fig. 5 is a schematic structural diagram of an external cavity semiconductor laser according to another embodiment of the present invention.

Fig. 6 is a schematic view showing a placement angle of a bandpass filter of an external cavity semiconductor laser according to another embodiment of the invention.

Fig. 7 is a light path diagram of an external cavity semiconductor laser according to another embodiment of the present invention.

Fig. 8 is a schematic structural diagram of an external cavity semiconductor laser according to another embodiment of the present invention.

Fig. 9 is a schematic view showing a placement angle of a bandpass filter of an external cavity semiconductor laser according to another embodiment of the invention.

Fig. 10 is a light path diagram of an external cavity semiconductor laser according to still another embodiment of the present invention.

Reference numerals illustrate:

1 is a single laser tube, 2 is a light beam, 3 is a fast axis collimating lens, 4 is a slow axis collimating lens, 5 is a total reflection mirror, 6 is a bottom plate with a step structure, 1.1-1.6 are respectively a first laser tube to a sixth laser tube, 2.1-2.6 are respectively a first light beam to a sixth light beam, 3.1-3.6 are respectively a first fast axis collimating lens to a sixth fast axis collimating lens, 7.1-7.6 are respectively a first filter plate to a sixth filter plate, and 8 is an external cavity mirror.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention. On the contrary, the embodiments of the invention include all alternatives, modifications and equivalents as may be included within the spirit and scope of the appended claims.

Referring to fig. 2, a first embodiment of the present invention proposes an external cavity semiconductor laser comprising an external cavity comprising a laser single tube, a filter and an external cavity mirror 8.

The laser monotube comprises a first laser monotube 1.1 and a second laser monotube 1.2, the first laser monotube 1.1 is used for emitting light beams in a first direction, and the second laser monotube 1.2 is used for emitting light beams in a second direction. The filter comprises a first filter 7.1 and a second filter 7.2, and the second filter 7.2 is used for filtering out the light beam emitted by the second laser single tube 1.2 into the light beam of the second wave band; the first filter 7.1 is configured to filter a light beam emitted by the first laser single tube 1.1 to a light beam of a first wavelength band, reflect the light beam of a second wavelength band, and then emit the light beam of the second wavelength band to the external cavity mirror 8 in a first direction, where the first wavelength band is separated from the second wavelength band. The light beams emitted by the first laser single tube 1.1 and the second laser single tube 1.2 oscillate back and forth in the outer cavity, perform wavelength beam combination, and output laser light through the outer cavity mirror 8.

Wavelength combining (also known as spectral combining or simply wavelength combining) is a technique in the field of power scaling by beam combining. The object is to combine the light beam of the first wavelength band with the light beam of the second wavelength band to obtain a light beam which has a very high power and which maintains the quality of the light beam as much as possible, so that the brightness of the laser light is improved.

It can be understood that the light beam emitted by each laser single tube has a certain range of wavelengths, and the spectral range through which the filter can transmit can be selected according to requirements. The first light beam 2.1 emitted by the first laser single tube 1.1 is filtered out by the first filter 7.1, the first light beam 2.1 in the first wave band advances along the first direction, reaches the outer cavity mirror 8, and returns to the first laser single tube 1.1 according to the original path. The second laser single tube 1.2 is filtered out the second light beam 2.2 of the second wave band by the second filter 7.2, advances along the second direction, is reflected by the first filter 7.1 after reaching the first filter 7.1, and the reflected second light beam 2.2 is transmitted along the first direction, reaches the outer cavity mirror 8 and is returned to the second laser single tube 1.2 according to the original path. The wavelength bands through which the two filters are allowed to transmit are not identical and the second light beam 2.2 of the second wavelength band cannot pass through the first filter 7.1 but is only reflected by the first filter 7.1. Since the first filter 7.1 also serves to reflect the second light beam 2.2 in the second wavelength band, the first and second wavelength bands cannot overlap or coincide. If the first and second bands overlap or coincide, the second light beam 2.2 partially or completely passes through the first filter 7.1, so that the first filter 7.1 cannot fully reflect the second light beam 2.2, and finally wavelength beam combination cannot be performed or the wavelength beam combination effect is poor.

In this embodiment, the first laser monotube 1.1 and the second laser monotube 1.2 are both semiconductor lasers. Semiconductor lasers use semiconductor materials as gain media. And resonant cavities formed by external cavity mirrors are arranged at two ends of the gain medium. The outer cavity means that the resonant cavity is of a full outer cavity structure, namely, the first laser single tube 1.1, the second laser single tube 1.2, the filter and the outer cavity mirror 8 are completely separated from each other in space. The beam propagates back and forth in the gain medium in the cavity, and is amplified once per pass. In one embodiment, the laser monotube is an edge emitting laser.

In one embodiment, the filter is a bandpass filter. The band-pass filter has a plurality of film layers with high refractive index and low refractive index which are alternately coated, and the band-pass filter is used for transmitting light beams with different wave bands according to different incident angles of incident light beams of a single laser tube. When the filter is a band-pass filter, the inventor finds that the effect of wavelength beam combination is better.

In one embodiment, a collimating lens is arranged in front of a first end of a laser single tube, the first end of the laser single tube is a transmission part, a second end of the laser single tube is a reflection part, and a junction area is arranged between the first end and the second end of the laser single tube; the transmission part is used for making the light beam incident and emergent; the reflecting part is used for reflecting the light beam, and the junction area is used for carrying out oscillation amplification on the light beam. The laser single tube is equivalent to a rectangular dielectric waveguide cavity. The junction region is made of a semiconductor material, and various semiconductor materials can be used, and can be designed according to practical needs without specific limitation. The two end faces of the junction region are natural cleavage surfaces of the crystal, and the two surfaces are extremely smooth and can be directly used as parallel reflection mirrors to form an optical resonant cavity. Optionally, the collimating lens is a fast axis collimating lens. The transmission part is plated with an antireflection film, and the antireflection film can increase the light transmittance. The reflecting part is plated with a total reflection film. The total reflection film can make the reflection portion have a sufficient reflectance.

In one embodiment, the external cavity mirror 8 is a partially transmissive mirror, and the partially transmissive mirror is used to reflect a part of the light beam emitted from the single laser tube, and a part of the light beam is transmitted through the output laser. The position of the external cavity mirror 8 can be adjusted to keep the external cavity semiconductor laser outputting laser stably for a long time.

In one embodiment, the number of the laser single tubes is N, the number of the band-pass filters is N, and the band-pass filters have N pass bands; the kth laser single tube is used for emitting light beams in the kth direction; a kth band-pass filter is arranged in front of the first end of the kth laser single tube; the kth band-pass filter is used for filtering out the light beam emitted by the kth laser single tube, reflecting the light beam from the kth+1th to the nth band, and then directing the light beam to the kth-1th band-pass filter in the kth direction or to the external cavity lens 8 when k=1, wherein N is a positive integer greater than 2, and k is a positive integer less than or equal to N. The planes of the bottoms of the N laser single tubes are coplanar.

Fig. 5 is a schematic structural diagram of an external cavity semiconductor laser according to another embodiment of the present invention. The difference between the two embodiments shown in fig. 2 and 5 is the number of single laser tubes and filters. In the embodiment shown in fig. 5, the number of laser single tubes is 6, and the number of filters is 6. In the embodiment shown in fig. 5 in combination with fig. 3 and 4, the filter is a band-pass filter, and optionally, the six band-pass filters (7.1-7.6) have the same coating structure, and the coating structure includes multiple layers with alternating high refractive index (nl=3) and low refractive index (nh=1.7). Table 1 shows a film structure of a band pass filter. Wherein the film layer with the film layer number of 1 is next to the substrate of the band-pass filter, the film layer with the film layer number of 109 is next to air, dL is 152.5nm, dH is 86.4167nm, and dL and dH represent the thicknesses of the low refractive index layer and the high refractive index layer.

Film layer number

Thickness of (L)

Refractive index

Film layer number

Thickness of (L)

Refractive index

Film layer number

Thickness of (L)

Refractive index

Film layer number

Thickness of (L)

Refractive index

Film layer number

Thickness of (L)

Refractive index

1

dH

nH

23

dH

nH

45

dH

nH

67

dH

nH

89

dH

nH

2

dL

nL

24

dL

nL

46

dL

nL

68

dL

nL

90

dL

nL

3

dH

nH

25

dH

nH

47

dH

nH

69

dH

nH

91

dH

nH

4

dL

nL

26

dL

nL

48

dL

nL

70

dL

nL

92

dL

nL

5

dH

nH

27

dH

nH

49

dH

nH

71

dH

nH

93

dH

nH

6

dL

nL

28

dL

nL

50

dL

nL

72

dL

nL

94

dL

nL

7

dH

nH

29

dH

nH

51

dH

nH

73

dH

nH

95

dH

nH

8

dL

nL

30

dL

nL

52

dL

nL

74

dL

nL

96

dL

nL

9

dH

nH

31

dH

nH

53

dH

nH

75

dH

nH

97

dH

nH

10

dL

nL

32

dL

nL

54

dL

nL

76

dL

nL

98

dL

nL

11

2*dH

nH

33

2*dH

nH

55

2*dH

nH

77

2*dH

nH

99

2*dH

nH

12

dL

nL

34

dL

nL

56

dL

nL

78

dL

nL

100

dL

nL

13

dH

nH

35

dH

nH

57

dH

nH

79

dH

nH

101

dH

nH

14

dL

nL

36

dL

nL

58

dL

nL

80

dL

nL

102

dL

nL

15

dH

nH

37

dH

nH

59

dH

nH

81

dH

nH

103

dH

nH

16

dL

nL

38

dL

nL

60

dL

nL

82

dL

nL

104

dL

nL

17

dH

nH

39

dH

nH

61

dH

nH

83

dH

nH

105

dH

nH

18

dL

nL

40

dL

nL

62

dL

nL

84

dL

nL

106

dL

nL

19

dH

nH

41

dH

nH

63

dH

nH

85

dH

nH

107

dH

nH

20

dL

nL

42

dL

nL

64

dL

nL

86

dL

nL

108

dL

nL

21

dH

nH

43

dH

nH

65

dH

nH

87

dH

nH

109

dH

nH

22

dL

nL

44

dL

nL

66

dL

nL

88

dL

nL

TABLE 1

Wavelength of

990nm

980nm

970nm

960nm

950nm

940nm

Maximum transmittance incident angle

41.6°

46.7°

51.7°

56.8°

62.3°

68.3°

TABLE 2

Table 2 shows the incidence angles at which the band pass filters corresponding to 6 wavelengths have the maximum transmittance. The angle of incidence is the angle between the direction of incidence of the beam of the laser monotube and the normal of the filter. Fig. 4 shows the transmittance of the band-pass filter for different wavelengths as a function of angle of incidence. Each wavelength lying within a band. Each band is separated. As shown in fig. 5 to 7, the k-th filter transmits the light beam emitted from the k-th laser single tube and reflects the light beam from the k+1th to 6-th laser single tubes by the arrangement position of the first to sixth laser single tubes (1.1 to 1.6) and the arrangement angle of the first to sixth filters (7.1 to 7.6). And the light beam of the kth laser single tube is transmitted at the corresponding kth filter and is reflected at the 1 st to the kth-1 k-1 filter. The reflection is reflected on the surface of the coated structure. When the kth filter sheet enables the light beams emitted by the kth laser single tube to pass through, the light beams emitted by the kth laser single tube can pass through the surface of the kth filter sheet with the film coating structure, or can pass through the surface of the kth filter sheet without the film coating structure, and the placement of the filter sheets is not limited.

For example, as shown in connection with fig. 5-7, the first filter 7.1 makes an angle of incidence of 68 ° with the first laser monotube 1.1, so that the first light beam 2.1 with the wavelength of 940nm can be transmitted after being emitted from the first laser monotube 1.1, and reflected back to the first laser monotube 1.1 after reaching the external cavity mirror 8, thereby locking the first laser monotube 1.1 at the wavelength of 940 nm. The second to sixth light beams (2.2-2.6) of the last 5 laser mono-tubes, i.e. the second to sixth laser mono-tubes (1.2-1.6), will be reflected by the first filter 7.1 and reach the external cavity mirror 8.

The sixth filter 7.6 forms an incidence angle of 42 ° with the sixth laser single tube 1.6, so that the sixth light beam 2.6 having a wavelength of 990nm can be emitted from the sixth laser single tube 1.6 and transmitted. The sixth light beam 2.6 is reflected by the first 5 filters (7.1-7.5) after passing through the sixth filter 7.6, reaches the external cavity mirror 8, and then is reflected by the first 5 filters (7.1-7.5), passes through the sixth filter 7.6 and returns to the sixth laser single tube 1.6, so that the sixth laser single tube 1.6 is locked at 990nm wavelength.

The principle of the trend of the optical paths of other filter plates and laser single tubes is the same, and the description is omitted here.

As can be seen from fig. 6, the k-th laser single tube emits the light beam into the k-th filter, and when k is different, the incident angle is also different.

According to the external cavity semiconductor laser provided in the embodiment shown in fig. 5, the first to sixth laser single tubes, the filter and the external cavity mirror are used to form an external cavity, and the laser single tube uses a semiconductor material as a gain medium to amplify light. According to the embodiment of the invention, six laser single tubes are utilized to perform wavelength (940 nm,950nm,960nm,970nm, 480 nm and 990 nm) beam combination, so that laser beams with higher power are obtained, and the power of the six laser single tubes is integrated, and meanwhile, the total beams are kept close to the beam parameter product of one laser single tube, so that the beam quality of laser is maintained, and the brightness of the laser beams is improved.

Fig. 8 is a schematic structural diagram of an external cavity semiconductor laser according to another embodiment of the present invention. The embodiment shown in fig. 8 differs from the embodiment shown in fig. 5 in that the second to sixth filter plates (7.2-7.6) are arranged at different angles. In other words, with the plane of the bottom of the single laser tube as a reference, in both embodiments, the yaw angles of the second to sixth filters (7.2-7.6) are not identical. Thus, the positions of the second to sixth laser single tubes (1.2-1.6) are different, and can be set according to actual needs.

Referring to fig. 8 to 10, the first to sixth laser single tubes (1.1 to 1.6) are arranged at positions and angles at which the first to sixth filters (7.1 to 7.6) are arranged such that the kth filter transmits the light beam emitted from the kth laser single tube and reflects the light beam from the (k+1) th to (6) th 6-k laser single tubes. And the light beam of the kth laser single tube is transmitted at the corresponding kth filter and is reflected at the 1 st to the kth-1 k-1 filter.

For example: the first filter 7.1 forms an incident angle of 68 degrees with the first single tube 1.1, so that the first light beam 2.1 with the wavelength of 940nm can be transmitted after being emitted from the first laser single tube 1.1, and is reflected back to the first laser single tube 1.1 after reaching the external cavity mirror 8, thereby locking the first laser single tube 1.1 on the wavelength of 940 nm. The second to sixth light beams (2.2-2.6) of the last 5 laser mono-tubes, i.e. the second to sixth laser mono-tubes (1.2-1.6), will be reflected by the filter 7.1 and reach the external cavity mirror 8.

According to the external cavity semiconductor laser provided in the embodiment shown in fig. 8, the first to sixth laser single tubes, the filter and the external cavity mirror are used to form an external cavity, and the laser single tube uses a semiconductor material as a gain medium to amplify light. According to the embodiment of the invention, six laser single tubes are utilized to perform wavelength (940 nm,950nm,960nm,970nm, 480 nm and 990 nm) beam combination, so that laser beams with higher power are obtained, and the power of the six laser single tubes is integrated, and meanwhile, the total beams are kept close to the beam parameter product of one laser single tube, so that the beam quality of laser is maintained, and the brightness of the laser beams is improved.

It should be noted that in the description of the present invention, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, in the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present invention, the azimuth or positional relationship indicated by the terms "left", "right", "front", "rear", etc., are based on the azimuth or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present invention.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and further implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. An external cavity semiconductor laser is characterized by comprising an external cavity, wherein the external cavity comprises a laser single tube, a filter and an external cavity mirror (8); the filter is a band-pass filter;

the laser monotube comprises a first laser monotube (1.1) and a second laser monotube (1.2), wherein the first laser monotube (1.1) is used for emitting light beams in a first direction; the second laser monotube (1.2) is used for emitting light beams in a second direction, and the light beams in the first direction and the light beams in the second direction intersect;

the filter comprises a first filter (7.1) and a second filter (7.2), and the second filter (7.2) is used for filtering out the light beam emitted by the second laser single tube (1.2) to the light beam of the second wave band; the first filter (7.1) is used for filtering out the light beam emitted by the first laser single tube (1.1) in a first wave band, reflecting the light beam in the second wave band and then emitting the light beam to the external cavity mirror (8) in a first direction, wherein the first wave band is separated from the second wave band;

the light beams emitted by the first laser single tube (1.1) and the second laser single tube (1.2) oscillate back and forth in the outer cavity to perform wavelength beam combination, and laser is output through the outer cavity mirror (8).

2. The external cavity semiconductor laser of claim 1, wherein the single laser tube is an edge-emitting laser.

3. The external cavity semiconductor laser according to claim 1, wherein the band-pass filter has a plurality of film layers with high refractive index and low refractive index coated alternately, and the band-pass filter is used for transmitting light beams of different wavebands according to different incident angles of incident light beams of the single tube of the laser.

4. The external cavity semiconductor laser according to claim 1, wherein a collimating lens is provided in front of a first end of the single laser tube, the first end of the single laser tube is a transmitting portion, a second end of the single laser tube is a reflecting portion, and a junction region is formed between the first end and the second end of the single laser tube;

5. The external cavity semiconductor laser according to claim 1, characterized in that the external cavity mirror (8) is a partially transmissive mirror for reflecting a part of the light beam emitted through the laser single tube and transmitting a part of the output laser light.

6. The external cavity semiconductor laser of claim 4, wherein said collimating lens is a fast axis collimating lens.

7. The external cavity semiconductor laser according to claim 4, wherein the transmissive portion is plated with an antireflection film and the reflective portion is plated with a total reflection film.

8. The external cavity semiconductor laser according to claim 3, wherein the number of the laser single tubes is N, the number of the band-pass filters is N, and the band-pass filters have N pass bands;

the kth laser monotube is used for emitting light beams in the kth direction;

a kth band-pass filter is arranged in front of the first end of the kth laser single tube; the kth band-pass filter is used for filtering out the light beam emitted by the kth laser single tube, reflecting the light beam from the kth+1th to the nth band, and then directing the light beam to the kth-1th band-pass filter in the kth direction or the external cavity mirror (8) when k=1, wherein N is a positive integer greater than 2, and k is a positive integer less than or equal to N.

9. The external cavity semiconductor laser of claim 8, wherein the planes of the bottoms of the N individual laser tubes are coplanar.