Wavelength multiplexing efficient optical fiber coupling system based on step prism

Abstract

The invention discloses a step prism-based wavelength multiplexing high-efficiency optical fiber coupling system, which comprises a plurality of groups of laser light sources, a plurality of step prisms, a collimating lens, a polarization beam combining prism, a beam expanding lens and a focusing lens, and is characterized in that the laser light sources enter the step prisms to realize wavelength beam combination, then pass through the polarization beam combining prism to realize polarization beam combination, and finally pass through the beam expanding lens in sequence to realize beam splitting; and a focus lens. The light beam path is effectively changed through repeated use of the wavelength beam combining surface of the step prism, so that efficient light beam dark space compression and wavelength beam combination are realized, the light beam quality in the fast axis direction is further improved, and the output power is improved by combining polarization beam combination; and finally, a beam expanding cylindrical mirror is adopted to homogenize the sizes of light spots in the fast axis direction and the slow axis direction. The whole system adopts a single prism to compress the light width and realize wavelength beam combination, and the use number of the prisms is reduced, so that the loss is effectively reduced, and compact and efficient optical fiber coupling is realized.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor laser beam shaping, and in particular to a wavelength multiplexing high-efficiency optical fiber coupling system based on a step prism. Background Art

[0002] Semiconductor lasers are widely used in industrial processing, laser pumping, biomedicine and other fields due to their advantages of small space, long life and high conversion rate between electricity and light. Most of the light-emitting bars on the market are packaged in a vertical stack, which greatly improves the power of semiconductor lasers. However, due to the need for heat dissipation, the heat sink has a certain thickness, resulting in dark areas in the fast axis direction, uneven beam quality on the fast and slow axes, and it is difficult for the beam to be coupled into the target optical fiber. Therefore, the beam shaping and beam combining of the fiber coupling module are crucial.

[0003] At present, the main methods for obtaining high-power fiber-coupled output from semiconductor lasers are wavelength combining and polarization combining, both of which can increase the output power without deteriorating the beam quality. For fiber coupling of semiconductor laser stacks, beam shaping is a must to eliminate the dark areas between bars. However, existing beam shaping technologies require many shaping prisms, which makes the system more complex and difficult to adjust. Summary of the invention

[0004] Purpose of the invention: In view of the above shortcomings, the present invention provides a wavelength multiplexing and efficient fiber coupling system based on step prism.

[0005] Technical solution: To solve the above problems, the present invention adopts a wavelength multiplexing high-efficiency fiber coupling system based on step prism, including multiple groups of laser light sources, several step prisms, collimating lenses, polarization beam combining prisms, beam expanders, and focusing lenses; the multiple groups of laser light sources include at least two groups of laser light sources with perpendicular incident directions and opposite polarization states, and each group of laser light sources includes wavelengths of λ 1 , 2 The collimating lens is arranged at the exit end of the laser light source; each group of laser light sources is arranged parallel to each other on both sides of a step prism, the step prism includes a horizontal plane, a slope surface and a reflecting surface, the horizontal plane and the slope surface form an angle of 135°, the two ends of the slope surface are connected to a horizontal plane, and the slope surface is plated with a transmission wavelength λ 1 , reflection wavelength λ 2 The film or transmission wavelength of the laser 2 , reflection wavelength λ 1 The horizontal surface and the slope surface are alternately arranged to form a stepped surface, and the reflecting surface is located on one side of the stepped surface;

[0006] The wavelength λ of each laser source 1 The laser passes through the plate with a transmission wavelength λ2 , reflection wavelength λ 1 The film, the wavelength λ in the laser light source 2 The laser passes through the plate with a transmission wavelength λ 1 , reflection wavelength λ 2 The laser film, part of the laser is directly reflected, and the other part of the laser enters the inside of the step prism. The laser entering the step prism is emitted from the step prism after passing through the slope surface and the reflecting surface. Multiple groups of laser light sources then pass through the polarization beam combining prism to achieve polarization beam combining, and finally pass through the beam expander and focusing lens in sequence.

[0007] Furthermore, the bottom surface of the step prism is parallel to the horizontal plane, and the reflecting surface includes a first reflecting surface and a second reflecting surface that are perpendicular to each other, the first reflecting surface forms an angle of 135° with the horizontal plane, and the second reflecting surface forms an angle of 135° with the bottom surface.

[0008] Furthermore, the multiple groups of laser light sources include a first laser light source group with a polarization state of P and a second laser light source group with a polarization state of S. The incident directions of the first laser light source group and the second laser light source group are perpendicular to each other, and the polarization beam combining prism is coated with a thin film that transmits P light and reflects S light.

[0009] Furthermore, it also includes setting a third laser light source group in parallel with the second laser light source group, and the polarization state of the third laser light source group is S state, and the third laser light source group realizes polarization beam combining with the first laser light source group and the second laser light source group through another polarization beam combining prism.

[0010] Furthermore, each group of laser light sources includes a group of wavelengths λ 1 A semiconductor laser stack and a set of wavelengths λ 2 The laser stack of the semiconductor laser stack, each group of laser stacks includes a number of bars.

[0011] Furthermore, the thickness H of the step prism 1 is 9-12 mm, the length L of the horizontal plane 1 The projected length L of the slope on the horizontal plane is 1.2-1.5 mm. 2 is 0.42-0.84 mm, and the length L of the first reflecting surface and the second reflecting surface 3 Equally, L3 is 5.4-5.7mm.

[0012] Furthermore, the collimating lens comprises a fast-axis collimating lens and a slow-axis collimating lens, the fast-axis collimating lens is a D-type aspherical cylindrical lens, and the slow-axis collimating lens is a micro-cylindrical lens array.

[0013] Furthermore, the light beam incident surfaces of the step prism, collimating lens, polarization beam combining prism, beam expander, and focusing lens are all coated with anti-reflection films, and the light beam reflecting surfaces are all coated with anti-reflection films.

[0014] Furthermore, the beam expander is a Galilean beam expander, which includes a plano-concave lens and a plano-convex cylindrical lens, and the beam expander is used to homogenize the spot size in the fast and slow axis directions.

[0015] Furthermore, the focusing mirror is an aspherical lens, which is used to couple the light beam into the target optical fiber.

[0016] Beneficial effects: Compared with the prior art, the significant advantage of the present invention is that the beam path is effectively changed by repeatedly using the wavelength combining surface of the step prism, thereby achieving efficient dark area compression and wavelength combining of the beam, thereby improving the beam quality in the fast axis direction, and combining with polarization combining to increase the output power; finally, a beam expansion cylindrical mirror is used to homogenize the spot size in the fast axis and slow axis directions. The entire system uses a single prism to compress the light width and achieve wavelength combining, reducing the number of prisms used, thereby effectively reducing the loss and achieving compact and efficient fiber coupling. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the optical fiber coupling system of the present invention;

[0018] Figure 2 Schematic diagram of the structure of the step prism of the present invention;

[0019] Figure 3 Schematic diagram of coating on the slope of the step prism of the present invention;

[0020] Figure 4 This is the optical path diagram of the laser light source of the present invention;

[0021] Figure 5 It is a schematic diagram of the structure of the beam expander of the present invention. DETAILED DESCRIPTION

[0022] like Figure 1 As shown, a wavelength multiplexing high-efficiency fiber coupling system based on step prism in this embodiment includes three groups of laser light sources, three step prisms 5, a collimating lens, two polarization beam combining prisms 8, a beam expander 9, and a focusing lens 10. The three groups of laser light sources are the first laser light source group 1, the second laser light source group 2, and the third laser light source group 3. Each group of laser light sources includes a group of wavelengths λ 1 A semiconductor laser stack and a set of wavelengths λ 2 The laser stack of the semiconductor laser stack, each group of laser stacks includes 16 bars, and eight bars are arranged on both sides of each step prism 5. Among them, the first laser light source group 1 includes a wavelength of λ 1 The first laser stack 11 and the wavelength λ 2 The second laser stack 12, the second laser light source group 2 includes a wavelength of λ 1The third laser stack 21 and the wavelength λ 2 The fourth laser stack 22, the third laser light source group 3 includes a wavelength of λ 1 The fifth laser stack 31 and the wavelength λ 2 The sixth laser stack 32. The incident directions of the second laser light source group 2 and the third laser light source group 3 are parallel to each other and the polarization states are both S state. The incident direction of the first laser light source group 1 is perpendicular to the second laser light source group 2 and the third laser light source group 3 and the polarization state is P state. A collimating lens is provided at the output end of each laser stack. The collimating lens includes a fast axis collimating lens 6 and a slow axis collimating lens 7. The fast axis collimating lens 6 is a D-type aspherical cylindrical lens, and the slow axis collimating lens 7 is a micro cylindrical lens array.

[0023] like Figure 2 As shown, the step prism 5 includes a horizontal plane 51, a slope 52, a reflective surface 53, and a bottom surface 54. The horizontal plane 51 and the slope 52 form an angle of 135°, and the two ends of the slope 52 are connected to a horizontal plane 51. The horizontal planes 51 and the slopes 52 are alternately arranged to form a step surface. The bottom surface 54 of the step prism 5 is parallel to the horizontal plane 51, and the reflective surface 53 is located on one side of the step surface. The reflective surface 53 includes a first reflective surface and a second reflective surface that are perpendicular to each other. The first reflective surface forms an angle of 135° with the horizontal plane 51, and the second reflective surface forms an angle of 135° with the bottom surface 54.

[0024] like Figure 3 As shown, the slope 52 is coated with a transmission wavelength λ 1 , reflection wavelength λ 2 The film or transmission wavelength of the laser 2 , reflection wavelength λ 1 In this embodiment, the slope surface of the upper half of the step surface is coated with a transmission wavelength λ 2 , reflection wavelength λ 1 The film A has a transmission wavelength λ 1 , reflection wavelength λ 2 The laser film B, correspondingly, the wavelength of the laser light source is λ 1 The laser stack is incident from the upper half of the step surface with a wavelength of λ 2 The laser stack is incident from the lower half of the step surface. The thickness H of the step prism 5 1 is 9-12 mm, and the length L of the horizontal plane 51 1 The projection length L of the slope 52 on the plane where the horizontal plane 51 is located is 1.2-1.5 mm. 2 is 0.42-0.84 mm, and the length L of the first reflecting surface and the second reflecting surface 3 Equally, L3 is 5.4-5.7mm.

[0025] The two polarization beam combining prisms 8 are coated with a film that transmits P light and reflects S light. The two polarization beam combining prisms 8 are placed at a certain distance and at a 90° angle. The first polarization beam combining prism 8 is used to realize the polarization beam combining of the first laser light source group 1 and the second laser light source group 2, and the second polarization beam combining prism 8 is used to realize the polarization beam combining of the third laser light source group 3 and the other two groups of laser light sources. Figure 5 As shown, the beam expander 9 is a Galilean beam expander, including a plano-concave and plano-convex cylindrical lens, and the beam expander 9 is used to homogenize the spot size in the fast and slow axis directions. The focusing lens 10 is an aspheric lens, which is used to couple the light beam into the target optical fiber. The beam incident surfaces of the step prism 5, the collimating lens, the polarization beam combining prism 8, the beam expander 9, and the focusing lens 10 are all coated with anti-reflection coatings, and the beam reflection surfaces are all coated with anti-reflection coatings to reduce energy loss and improve light-to-light conversion efficiency.

[0026] like Figure 4 As shown, the optical path of the fiber coupling system of the present invention is specifically as follows: when the laser light source passes through the step prism 2, the laser light source incident from above the step surface is directly reflected by the slope surface 52, does not enter the step prism 5, and directly exits from the exit end of the step prism 5; the laser light source incident from below the step surface passes through the bottom surface 54 and enters the step prism 5, and is then reflected by the slope surface 52 and the reflection surface 53 in turn, and finally exits from the exit end of the step prism 5; thus, the wavelength λ in the laser light source is completed. 1 , 2 Wavelength combination of lasers. After being emitted by the step prism 5, each group of laser light sources passes through the polarization beam combination prism 8 to complete polarization beam combination, and finally passes through the beam expander 9 and the focusing lens 10 in sequence to enter the target optical fiber 11.

[0027] The present invention effectively changes the beam path by repeatedly using the wavelength combining surface of the step prism, thereby achieving efficient dark area compression and wavelength combining of the beam, thereby improving the beam quality in the fast axis direction, and combining with polarization combining to increase the output power; finally, a beam expansion cylindrical mirror is used to homogenize the spot size in the fast axis and slow axis directions. The entire system uses a single prism to compress the light width and achieve wavelength combining, reducing the number of prisms used, thereby effectively reducing losses and achieving compact and efficient fiber coupling.

Claims

1. A wavelength multiplexing high-efficiency optical fiber coupling system based on step prism, characterized in that: The invention comprises a plurality of groups of laser light sources, a plurality of step prisms (5), a collimating lens, a polarization beam combining prism (8), a beam expander (9), and a focusing lens (10); the plurality of groups of laser light sources comprises at least two groups of laser light sources with perpendicular incident directions and opposite polarization states, each group of laser light sources comprises two lasers with wavelengths λ1 and λ2 respectively, and the collimating lens is arranged at the exit end of the laser light source; each group of laser light sources is arranged parallel to each other on both sides of a step prism (5), and the step prism (5) comprises A horizontal plane (51), a slope surface (52) and a reflection surface (53), wherein the horizontal plane (51) and the slope surface (52) form an angle of 135°, and the two ends of the slope surface (52) are respectively connected to a horizontal plane (51), and the slope surface (52) is plated with a thin film that transmits a laser with a wavelength λ1 and reflects a wavelength λ2, or a thin film that transmits a wavelength λ2 and reflects a wavelength λ1; the horizontal plane (51) and the slope surface (52) are alternately arranged to form a stepped surface, and the reflection surface (53) is located on one side of the stepped surface; The laser light with wavelength λ1 in each group of laser light sources passes through a thin film coated with a transmission wavelength λ2 and a reflection wavelength λ1. The laser light with wavelength λ2 in the laser light source passes through a thin film coated with a transmission wavelength λ1 and a reflection wavelength λ2. A portion of the laser light is directly reflected, and another portion of the laser light enters the inside of the step prism (5). The laser light entering the inside of the step prism (5) is emitted out of the step prism (5) after passing through a slope surface (52) and a reflection surface (53). The multiple groups of laser light sources then pass through a polarization beam combining prism (8) to realize polarization beam combining, and finally pass through a beam expander (9) and a focusing lens (10) in sequence.

2. The optical fiber coupling system according to claim 1, characterized in that: The bottom surface (54) of the step prism (5) is parallel to the horizontal plane (51); the reflection surface (53) comprises a first reflection surface and a second reflection surface which are perpendicular to each other; the first reflection surface forms an angle of 135° with the horizontal plane (51); and the second reflection surface forms an angle of 135° with the bottom surface (54).

3. The optical fiber coupling system according to claim 1, wherein: The multiple groups of laser light sources include a first laser light source group (1) with a polarization state of P and a second laser light source group (2) with a polarization state of S. The incident directions of the first laser light source group (1) and the second laser light source group (2) are perpendicular to each other. The polarization beam combining prism (8) is coated with a thin film that transmits P light and reflects S light.

4. The optical fiber coupling system according to claim 3, characterized in that: The invention also comprises a third laser light source group (3) arranged in parallel with the second laser light source group (2), wherein the polarization state of the third laser light source group (3) is an S state, and the third laser light source group (3) is polarized and combined with the first laser light source group (1) and the second laser light source group (2) through another polarization beam combining prism (8).

5. The optical fiber coupling system according to claim 1, wherein: Each group of laser light sources includes a group of semiconductor laser stacks with a wavelength of λ1 and a group of semiconductor laser stacks with a wavelength of λ2, and each group of laser stacks includes a plurality of bars.

6. The optical fiber coupling system according to claim 2, wherein: The thickness H1 of the step prism (5) is 9-12 mm, the length L1 of the horizontal plane (51) is 1.2-1.5 mm, the projection length L2 of the slope surface (52) on the plane where the horizontal plane (51) is located is 0.42-0.84 mm, and the length L3 of the first reflecting surface and the second reflecting surface are equal, and L3 is 5.4-5.7 mm.

7. The optical fiber coupling system according to claim 1, wherein: The collimating lens comprises a fast-axis collimating lens (6) and a slow-axis collimating lens (7); the fast-axis collimating lens (6) is a D-type aspherical cylindrical lens, and the slow-axis collimating lens (7) is a micro-cylindrical lens array.

8. The optical fiber coupling system according to claim 1, wherein: The light beam incident surfaces of the step prism (5), collimating lens, polarization beam combining prism (8), beam expander (9), and focusing lens (10) are all coated with anti-reflection films, and the light beam reflection surfaces are all coated with anti-reflection films.

9. The optical fiber coupling system according to claim 1, wherein: The beam expander (9) is a Galilean beam expander, comprising a plano-concave lens and a plano-convex cylindrical lens. The beam expander (9) is used to homogenize the light spot size in the fast and slow axis directions.

10. The optical fiber coupling system according to claim 1, wherein: The focusing lens (10) is an aspherical lens and is used to couple the light beam into the target optical fiber.

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