Device for polarization separation and beam shaping of semiconductor laser array

Abstract

This invention provides an apparatus for polarization separation and beam shaping of a semiconductor laser array, comprising a rotatable half-wave plate, a polarizing beam splitter prism, a quarter-wave plate, a total reflection mirror, and right-angle stepped prisms disposed at the upper and lower ends of the polarizing beam splitter prism. This embodiment achieves adjustment of the P- and S-components in the beam by rotating the half-wave plate; the polarizing beam splitter prism enables total internal reflection of the S-component, which exits through the upper right-angle stepped prism; the P-component passes through the polarizing beam splitter prism, is converted to right-hand circularly polarized light by the quarter-wave plate, is converted to left-hand circularly polarized light by reflection from the total reflection mirror, and is converted back to S-component by the quarter-wave plate before exiting through the lower right-angle stepped prism, thus achieving polarization separation and beam shaping of the semiconductor laser array.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, and in particular to a device for polarization separation and beam shaping of semiconductor laser arrays. Background Technology

[0002] Semiconductor lasers possess numerous advantages, including low cost, high efficiency, compact structure, wide wavelength range, and high reliability. However, drawbacks such as low output power, poor beam quality, and low power density limit their application as direct light sources. Therefore, improving semiconductor laser output power, beam quality, and output brightness has become a significant technological bottleneck in the development of semiconductor lasers.

[0003] Semiconductor lasers can be classified into three types based on the number of light-emitting units and the packaging method: single-tube, bar, and stacked array. Compared with single-tube and bar, semiconductor laser stacked array involves stacking semiconductor laser bars along the fast axis. Therefore, the output power of semiconductor laser stacked array is generally several to tens of times higher than that of semiconductor laser bars. Currently, the highest output power of commercially available semiconductor laser stacked array devices can reach tens of thousands of watts or more.

[0004] However, due to the existence of dark areas between the light spots on the fast axis, superposition degrades the beam quality of the fast axis. Therefore, how to maintain the power of the semiconductor laser array while improving its output beam quality has become one of the key research directions. In 2006, Lincoln Laboratory in the United States first applied open-loop spectral beam combining to semiconductor laser arrays, achieving an output laser power of 89.5W, a spectral beam combining efficiency of 75%, and a spectral width of 14nm. In 2015, the China Academy of Engineering Physics used semiconductor laser arrays for spectral beam combining, achieving an output power greater than 120W, an electro-optical conversion efficiency greater than 48%, a fast-axis beam quality of 11.5, and a slow-axis beam quality of 10.2.

[0005] Currently, spectral beam combining for semiconductor laser arrays is mainly done in the slow axis direction. Since array spectral beam combining cannot solve the problem of fast axis beam quality degradation when spatial spot superposition occurs, the improvement in laser brightness is very limited. Summary of the Invention

[0006] The summary section of this invention provides a brief overview of the concepts, which will be described in detail in the detailed description section that follows. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0007] Some embodiments of the present invention provide apparatus for polarization separation and beam shaping of semiconductor laser arrays to solve the technical problems mentioned in the background section above.

[0008] Some embodiments of the present invention provide an apparatus for polarization separation and beam shaping of a semiconductor laser array, comprising a rotatable half-wave plate, a polarizing beam splitter prism, a quarter-wave plate, a total reflection mirror, and right-angle stepped prisms disposed at the upper and lower ends of the polarizing beam splitter prism, wherein...

[0009] The P- and S-components in the beam are adjusted by rotating the half-wave plate.

[0010] A polarizing beam splitter can cause S-beams to undergo total internal reflection and exit through the upper right-angle stepped prism toward the total internal reflection mirror;

[0011] The P-beam passes through the polarizing beam splitter, becomes right-handed circularly polarized light through a quarter-wave plate, becomes left-handed circularly polarized light through reflection by the total internal reflection mirror, and becomes S-beam again through a quarter-wave plate. After passing through the right-angle stepped prism below, it exits towards the total internal reflection mirror.

[0012] Optionally, the rotatable half-wave plate is used to cause a phase delay between the two polarization states of the light beam, thereby changing the polarization state of the light beam by changing the angle between the optical axis and the direction of the electric field of the output beam.

[0013] Optionally, the optical adhesive surface of the polarizing beam splitter is coated with a polarizing beam splitting film, and all right-angled surfaces are coated with an anti-reflection film.

[0014] Optionally, the polarizing beam splitter is used to enable the S-beam to be fully emitted and incident into the right-angle stepped prism.

[0015] Optionally, the polarizing beam splitter is used to allow P-light to pass through the polarizing beam splitter prism.

[0016] Optionally, the polarizing beam splitter is made of ultraviolet fused silica.

[0017] Optionally, the vertical height of the stepped slope of the right-angle step prism should not be less than the width of the light emitted by a single bar along the fast axis.

[0018] Optionally, the quarter-wave plate is used to convert the left-handed and right-handed circularly polarized light of the P-beam transmitted through the polarizing beam splitter.

[0019] Optionally, the quarter-wave plate is made of quartz crystal.

[0020] Optionally, the total reflection mirror is used to fold back the optical path and realize the mirror conversion between right-handed and left-handed circularly polarized light.

[0021] The above embodiments of the present invention have the following beneficial effects:

[0022] The beam emitted by the semiconductor laser array is collimated by the fast and slow axis collimating array and then enters a rotatable half-wave plate placed in front of the polarizing beam splitter. The P- and S-components in the beam are adjusted by rotating the rotatable half-wave plate.

[0023] As the beam enters the polarizing beam splitter, the S-beam cannot pass through the polarization separation film and undergoes total internal reflection. It then enters the stepped slope of the right-angle stepped prism above and exits to the right, thus compressing the beam in the fast axis direction.

[0024] For P-beams, they are directly transmitted through the polarizing beam splitter and into a quarter-wave plate. The quarter-wave plate converts the P-beams into right-hand circularly polarized light. As the light path advances, the right-hand circularly polarized light is incident on the surface of the total reflection mirror.

[0025] Due to the specular reflection of the total internal reflection mirror, right-handed circularly polarized light is converted into left-handed circularly polarized light and propagates in the opposite direction along the original light path. When the beam passes through the quarter-wave plate again, since the beam is now left-handed circularly polarized, it is converted into S-beam after passing through the quarter-wave plate. As the light continues forward, the S-beam undergoes total internal reflection at the polarizing beam splitter and is incident on the stepped slope of the right-angle stepped prism below, exiting from the right as well.

[0026] Thus, polarization separation and beam shaping of semiconductor laser arrays were achieved. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of an embodiment of the device for polarization separation and beam shaping of semiconductor laser arrays according to the present invention;

[0029] Figure 2 This is a schematic diagram of one embodiment of the apparatus for polarization separation and beam shaping of semiconductor laser arrays according to the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Rotatable half-wave plate; 2. Polarizing beam splitter prism; 3. Right-angle stepped prism; 4. Quarter-wave plate; 5. Total reflection mirror. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Please refer to the following first. Figure 1 , Figure 1 This is a schematic diagram of one embodiment of the apparatus for polarization separation and beam shaping of a semiconductor laser array according to the present invention. Figure 1 As shown, the device for polarization separation and beam shaping of semiconductor laser arrays includes a rotatable half-wave plate 1, a polarizing beam splitter prism 2, a right-angle stepped prism 3, a quarter-wave plate 4, and a total reflection mirror 5.

[0037] The aforementioned rotatable half-wave plate 1, also known as a phase delayer, can cause a certain phase delay between the two polarization states of light in a beam. By changing the angle between the optical axis and the direction of the electric field of the output beam, the polarization state of the beam can be changed.

[0038] The aforementioned polarizing beam splitter 2 is positioned to the right of the rotatable half-wave plate 1. Figure 1 (In the direction of the middle), it is made of ultraviolet fused silica, with a polarizing beam-splitting film coated on the optical adhesive surface, and an anti-reflection film coated on all right-angled surfaces.

[0039] The aforementioned right-angle stepped prism 3 is disposed on the upper and lower end faces of the polarizing beam splitter 2. The vertical height of the stepped inclined surface of the right-angle stepped prism 3 should not be less than the width of the light emitted by a single bar along the fast axis.

[0040] The quarter-wave plate 4 mentioned above is made of quartz crystal and can realize the conversion between linearly polarized light and left-handed and right-handed circularly polarized light.

[0041] The aforementioned total reflection mirror 5 can refract the optical path and realize the mirror conversion between right-hand circularly polarized light and left-hand circularly polarized light.

[0042] Please see Figure 2 , Figure 2 This is a schematic diagram of one embodiment of the apparatus for polarization separation and beam shaping of a semiconductor laser array according to the present invention. Figure 2 As shown, the beam emitted by the semiconductor laser array is collimated by the fast and slow axis collimating array and then enters the rotatable half-wave plate 1 placed in front of the polarization beam splitter 2. The P- and S- components in the beam are adjusted by rotating the rotatable half-wave plate 1.

[0043] As the light beam enters the polarizing beam splitter 2, a polarization separation film is coated on the cemented surface of the polarizing beam splitter 2. For S-beams, the S-beam cannot pass through the polarization separation film and undergoes total internal reflection at this point. It then enters the stepped inclined surface of the right-angle stepped prism 3 above and exits to the right, achieving compression of the beam in the fast axis direction. For P-beams, they are directly transmitted through the polarization separation film and enter the quarter-wave plate 4. The quarter-wave plate 4 achieves the conversion of P-beams into right-hand circularly polarized light. As the light path advances, the right-hand circularly polarized light is incident on the surface of the total reflection mirror 5.

[0044] Due to the specular reflection of the total internal reflection mirror 5, the right-handed circularly polarized light is converted into left-handed circularly polarized light and propagates in the opposite direction along the original light path. When the beam passes through the quarter-wave plate 4 again, since the beam is now left-handed circularly polarized, it is converted into S-beam after passing through the quarter-wave plate 4. As the light path advances, the S-beam undergoes total internal reflection at the polarization separation film and is incident on the stepped inclined surface of the right-angle stepped prism 3 below, exiting from the right as well.

[0045] Thus, polarization separation and beam shaping of semiconductor laser arrays were achieved.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for polarization separation and beam shaping of semiconductor laser arrays, characterized in that, The system includes, in sequence, a rotatable half-wave plate, a polarizing beam splitter, a quarter-wave plate, a total reflection mirror, and right-angle stepped prisms positioned at the top and bottom ends of the polarizing beam splitter. The P- and S-components in the beam are adjusted by rotating the half-wave plate. A polarizing beam splitter can cause total internal reflection of S-beams and allow them to exit through the upper right-angle stepped prism toward the total internal reflection mirror; The P-beam passes through the polarizing beam splitter, becomes right-handed circularly polarized light through a quarter-wave plate, becomes left-handed circularly polarized light through reflection by the total internal reflection mirror, and becomes S-beam again through a quarter-wave plate. After passing through the right-angle stepped prism below, it exits towards the total internal reflection mirror.

2. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 1, characterized in that, The rotatable half-wave plate is used to delay the phase of the two polarization states of the light beam, thereby changing the polarization state of the light beam by changing the angle between the optical axis and the direction of the electric field of the output beam.

3. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 1, characterized in that, The polarizing beam splitter has a polarizing beam splitting film coated on its optical adhesive surface, and all right-angled surfaces are coated with an anti-reflection film.

4. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 3, characterized in that, The polarizing beam splitter is used to enable the S-beam to be fully emitted and enter the right-angle stepped prism.

5. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 3, characterized in that, The polarizing beam splitter is used to allow P-light to pass through the polarizing beam splitter prism.

6. The apparatus for polarization separation and beam shaping of semiconductor laser arrays according to claim 1, characterized in that, The polarizing beam splitter is made of ultraviolet fused silica.

7. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 1, characterized in that, The vertical height of the stepped slope of the right-angle step prism should not be less than the width of the light emitted by a single bar along the fast axis.

8. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 5, characterized in that, The quarter-wave plate is used to convert the left-hand circularly polarized light and the right-hand circularly polarized light of the P-beam transmitted through the polarizing beam splitter.

9. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 8, characterized in that, The quarter-wave plate is made of quartz crystal.

10. The device for polarization separation and beam shaping of a semiconductor laser stack according to claim 1, characterized in that, The total reflection mirror is used to refract the optical path and realize the mirror conversion between right-hand circularly polarized light and left-hand circularly polarized light.

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