A device for enhancing the output power of a quantum cascade laser based on polarization beam combining

Abstract

This utility model relates to a device for improving the output power of a quantum cascade laser based on polarization beam combining. The device includes a base plate, two quantum cascade lasers, a standard collimating lens, a half-wave plate, a polarizer, a high-reflectivity mirror, an optical window, and a heat sink. The two quantum cascade lasers output 4.6μm wavelength lasers respectively. After collimation by the standard collimating lens, one of the laser beams is converted from S-polarization to P-polarization by the half-wave plate. Subsequently, the two P-polarized laser beams are guided by the high-reflectivity mirror and spatially coaxially combined at the polarizer, finally outputting the laser through the optical window. The device achieves stable fixation and precise positioning of each optical component through a precise mechanical structure, and the system's thermal management is achieved in conjunction with the housing and heat sink, effectively improving the laser output power and stability.

Description

Technical Field

[0001] This utility model belongs to the field of laser equipment technology, specifically relating to a device for improving the output power of a quantum cascade laser based on polarization beam combining. Background Technology

[0002] Quantum cascade lasers (QCLs) are semiconductor lasers that operate based on the principle of electron transitions between metastable energy levels. They offer advantages such as a wide tunable wavelength range, high single-mode output stability, and a large operating temperature range, making them particularly promising for applications in the mid-infrared band. They are suitable for precision fields such as gas detection, infrared imaging, spectral analysis, and optoelectronic countermeasures. While the output power of quantum cascade lasers has improved with advancements in modern semiconductor and optical technologies, single-die QCL devices are still limited by physical constraints such as chip size and thermal management capabilities, making it difficult to meet the high-energy laser requirements of mid- and long-wavelength optoelectronic countermeasures applications.

[0003] To address the issue of insufficient power per quantum cascade laser (QCL), one common method to increase QCL output power is spatial splicing, which involves spatially superimposing the laser outputs of 3 to 7 quantum cascaded lasers to achieve linear superposition of laser power. However, this approach has significant limitations in practical applications. The number of output beams typically matches the number of lasers spliced, resulting in a dispersed output beam that is difficult to form a standard single optical axis. This hinders the design of subsequent optical systems such as beam expanders and focusrs, thus limiting the performance of high-power quantum cascaded lasers in applications requiring precision focusing and long-distance energy transmission.

[0004] Furthermore, existing splicing and beam combining structures suffer from problems such as high requirements for optical path alignment accuracy, complex structures, and difficulties in debugging. Especially when using traditional mirror group designs, the laser output direction consistency is poor, making them susceptible to environmental temperature or vibration, causing beam position shifts, resulting in energy loss or unstable output. At the same time, some existing beam combining devices lack effective control over the laser polarization state, making it difficult to achieve true coaxial beam combining of multiple laser beams in space, further reducing beam combining efficiency and output quality. Utility Model Content

[0005] To address the problems existing in the prior art, the purpose of this utility model is to provide a device for improving the output power of a quantum cascade laser based on polarization beam combining. This device has a compact structure, high optical path stability, and can achieve effective laser beam combining through polarization matching, thereby improving the overall output power of the quantum cascade laser.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A device for improving the output power of a quantum cascade laser based on polarization beam combining includes a base plate. Two quantum cascade lasers are fixed to the upper surface of the base plate near the left side. A standard collimating lens is fixed to the upper surface of the base plate to the right of the two quantum cascade lasers. A polarizer and a high-reflectivity mirror are fixed to the upper surface of the base plate to the right of the two standard collimating lenses. A half-wave plate is placed between the polarizer and the standard collimating lens below. The high-reflectivity mirror reflects light forward to the polarizer.

[0008] A heat dissipation cover is detachably fixed to the upper side of the base plate, and an optical window is provided on the right end face of the cover at the position corresponding to the polarizer.

[0009] Furthermore, a support plate is provided below both the polarizer and the high-reflectivity mirror. Two clamping plates are fixed on the upper surface of the support plate to hold the polarizer or high-reflectivity mirror in the middle. The surfaces of the polarizer and the high-reflectivity mirror are fixed with protrusions near the lower edge.

[0010] Furthermore, a first fixing plate is provided below the standard collimator, and a positioning ring for positioning and installing the standard collimator is fixed on the upper side of the first fixing plate. A pressure ring is provided on the upper side of the positioning ring, which is pressed against the upper side of the standard collimator. One end of the pressure ring and the positioning ring are hinged, and the other end of both the pressure ring and the positioning ring is fixed with a connecting plate. The upper and lower connecting plates are fixedly connected by connecting screws.

[0011] Furthermore, a collar is fitted on the outer side of the half-wave plate, and a second fixing plate is fixed on the lower side of the collar.

[0012] Furthermore, a boss is fixed to the upper surface of the base plate, and mounting plates are fixed to the base plate near the four corners. Multiple anti-slip screws are installed on both the front and rear sides of the boss.

[0013] Furthermore, the lower end of the cover is fitted onto the outside of the boss, and multiple threaded holes are provided on both the front and rear sides of the cover. The upper surface of the cover is fixed with evenly arranged heat sinks.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] This invention utilizes two quantum cascade lasers that output 4.6μm wavelength laser light, combined with a standard collimating lens, a half-wave plate, a polarizer, and a high-reflectivity mirror to construct a polarization beam combining optical path. This allows the lasers output from the two lasers to be coaxially combined, effectively overcoming the limitation of output power in single-core quantum cascade lasers. It enables superimposed laser power output, improves the overall output efficiency of the mid-infrared laser source, and meets the demand for high-power mid-infrared laser sources in scenarios such as optoelectronic countermeasures and infrared imaging.

[0016] This invention uses a standard collimating lens to initially collimate the laser beam, ensuring a stable and consistent laser output direction and providing a precise optical axis reference for subsequent optical components. Furthermore, a half-wave plate is added to the collimating optical path to convert S-polarized light into P-polarized light, ensuring that the polarization states of the two laser beams are consistent. This satisfies the selective transmission requirement of the polarizer for P-polarized light, ensuring that there is no optical loss due to polarization mismatch during subsequent beam combining, thereby improving beam combining efficiency. By using a polarizer, spatial beam combining of the laser outputs from the preceding and following lasers is achieved, allowing the two laser beams to form a single output optical axis. This avoids the problems of multiple output spots and difficulties in subsequent beam expansion and focusing caused by spatial splicing in existing technologies, improving the optical integration and controllability of the system.

[0017] This invention uses a high-reflectivity mirror to reflect the laser output from the rear laser to the polarizer position, where it is superimposed with the front laser beam within the polarizer. Combined with the alternative solution of using a high-refractive-index Brewster plate as the beam combining element, this further expands the adaptability of the device under different optical configurations and improves the structural versatility. The high-reflectivity mirror also effectively utilizes the spatial structure, optimizes the optical path layout, and makes the overall system more compact, facilitating integration into miniaturized laser platforms.

[0018] This invention employs components such as positioning rings, pressure rings, clamping plates, and locking protrusions to perform high-precision assembly of optical elements, ensuring the fixed stability and repeatability of each key optical component on the laser transmission path, thereby improving the installation stability and positioning effect of each optical element. At the same time, the combination of clamping plates and support plates provides rigid positioning of polarizers and high-reflectivity mirrors, further enhancing the structure's anti-interference capability and effectively overcoming the problem of easy displacement of optical elements in existing beam combining structures.

[0019] This invention features a heat dissipation housing and a base plate with a boss and threaded fastening mechanism, solving the heat dissipation problem that occurs in existing structures when multiple lasers operate for extended periods. The housing's top is equipped with uniformly arranged heat sinks combined with thermally conductive graphite pads, effectively improving the heat exchange efficiency of the laser module, reducing the overall system temperature rise, and ensuring the spectral stability and lifespan of the quantum cascade laser under high-power continuous operation. The optical window is made of infrared-high transmittance material, ensuring stable and efficient laser output after beam combining, enhancing the system's reliability in practical applications. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is a schematic diagram of the structure of the clamping plate and polarizer or high-reflection mirror of this utility model.

[0022] Figure 3 This is a schematic diagram of the standard collimating lens mounting structure of this utility model;

[0023] Figure 4 This is a schematic diagram of the half-wave plate mounting structure of this utility model;

[0024] Figure 5 This is a schematic diagram of the base plate of this utility model;

[0025] Figure 6 This is a schematic diagram of the cover of this utility model.

[0026] The attached diagram lists the components represented by each number as follows:

[0027] 1. Housing; 110. Heat sink; 120. Threaded hole; 2. Quantum cascade laser; 3. Base plate; 31. Mounting plate; 32. Fixing screw; 33. Boss; 4. Standard collimating lens; 41. Pressure ring; 42. Connecting plate; 43. Connecting screw; 44. Positioning ring; 45. First fixing plate; 5. Half-wave plate; 51. Collar ring; 52. Second fixing plate; 6. Polarizer; 7. High-reflection mirror; 8. Optical window; 9. Clamping protrusion; 10. Clamping plate; 11. Support plate. Detailed Implementation

[0028] To make the objectives and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of this utility model and does not strictly limit the scope of protection specifically claimed by this utility model.

[0029] like Figure 1As shown, a device for improving the output power of a quantum cascade laser based on polarization beam combining includes a base plate 3. The base plate 3 is made of aluminum alloy to ensure good mechanical strength and thermal conductivity, and its surface is anodized to improve corrosion resistance. Two quantum cascade lasers 2 are fixed to the upper surface of the base plate 3 near the left side. The quantum cascade lasers 2 use a 4.6μm center wavelength mid-infrared chip model QCL-4600 and are mounted by a heat sink to enhance thermal stability. Two standard collimating lenses 4 are fixed to the upper surface of the base plate 3 to the right of the two quantum cascade lasers 2. The standard collimating lenses 4 are made of germanium material with an anti-reflection coating to achieve efficient collimation of the mid-infrared laser. Polarization beams are fixed to the upper surface of the base plate 3 to the right of the two standard collimating lenses 4. The system consists of a polarizer 6 and a high-reflectivity mirror 7. The polarizer 6 uses a high-transmittance BBO crystal polarizer, and the high-reflectivity mirror 7 uses a metal reflective film structure, achieving a reflectivity of over 95% in the 4.6μm band. A half-wave plate 5 is placed between the polarizer 6 and the standard collimating mirror 4 below, used to convert S-polarized light into P-polarized light, thus satisfying the P-polarized transmission characteristics of the polarizer 6. The half-wave plate 5 is made of MgF2 material and has good optical delay performance. The high-reflectivity mirror 7 reflects the laser from the rear quantum cascade laser 2 forward to the position of the polarizer 6. The polarizer 6 transmits the laser in the corresponding polarization direction to achieve beam combining of the two laser beams. Alternatively, a high-refractive-index Brewster plate can be used instead of the polarizer 6 for beam combining to further reduce optical loss and improve beam combining efficiency.

[0030] like Figure 1 As shown, a heat dissipation cover 1 is detachably fixed on the upper side of the base plate 3; the cover 1 is set on the upper side of the base plate 3 to cover the internal structure of the device; a light window 8 is set on the right end face of the cover 1 at the position corresponding to the polarizer 6. The light window 8 is a ZnSe window with high infrared transmittance, which has good laser transmission performance and environmental sealing, and can effectively output the laser beam after polarization and beam combining.

[0031] like Figure 2 As shown, a support plate 11 is provided below both the polarizer 6 and the high-reflectivity mirror 7. The support plate 11 is made of high-strength stainless steel and is fixed to the base plate 3 by a threaded connection. Two clamping plates 10 are fixed on the upper surface of the support plate 11 to clamp the polarizer 6 or the high-reflectivity mirror 7 in the middle. The clamping plates 10 are made of aluminum alloy and have high-temperature resistant silicone pads inside to prevent pressure damage to the optical components during clamping. The surfaces of the polarizer 6 and the high-reflectivity mirror 7 are fixed with protrusions 9 near the lower edge. The protrusions 9 cooperate with the clamping plates 10 to position and fix the polarizer 6 and the high-reflectivity mirror 7.

[0032] like Figure 3As shown, a first fixing plate 45 is provided below the standard collimating lens 4. The first fixing plate 45 is made of nickel-plated carbon steel, which has good rigidity and stability. A positioning ring 44 for positioning and installing the standard collimating lens 4 is fixed on the upper side of the first fixing plate 45. The positioning ring 44 is made of aviation aluminum alloy and is precision machined by CNC. A pressure ring 41 is provided on the upper side of the positioning ring 44, which is pressed against the upper side of the standard collimating lens 4. One end of the pressure ring 41 and the positioning ring 44 are hinged to form a flip-up structure, which facilitates the installation and replacement of the standard collimating lens 4. A connecting plate 42 is fixed to the other end of the pressure ring 41 and the positioning ring 44. The upper and lower connecting plates 42 are fixedly connected by connecting screws 43. The connecting screws 43 adopt the M3 standard thread type and are made of 304 stainless steel to ensure a firm connection and corrosion resistance.

[0033] like Figure 4 As shown, a collar 51 is fitted on the outer side of the half-wave plate 5; a second fixing plate 52 is fixed on the lower side of the collar 51; the collar 51 and the second fixing plate 52 cooperate to install and fix the half-wave plate 5 so that the half-wave plate 5 is set at the corresponding optical path position.

[0034] like Figure 5 As shown, a boss 33 is fixed on the upper surface of the base plate 3. The boss 33 is machined by integral milling and has a height of 15mm and a width of 30mm. It is used to improve the installation stability of the cover 1. Mounting plates 31 are fixed near the four corners of the base plate 3. The mounting plates 31 are fixed to the base plate 3 by embedded nuts. The material of the mounting plates 31 is hard alloy steel plate, which is used to bear the external assembly force. Multiple locking screws 32 are installed on the front and rear sides of the boss 33. The locking screws 32 are M4×8mm. Their function is to limit the vertical sliding range of the cover 1 and prevent the offset caused by installation errors.

[0035] like Figure 6 As shown, the lower end of the housing 1 is fitted onto the outside of the boss 33; multiple threaded holes 120 are provided on both the front and rear sides of the housing 1. The threaded holes 120 are used to install fastening screws for fixing the housing 1. The standard thread specification is M5×10mm. They are used in conjunction with flat washers to enhance the force-bearing area; a uniformly arranged heat sink 110 is fixed on the upper surface of the housing 1. The heat sink 110 adopts a fin-type structure and is made of black anodized aluminum, which can improve the infrared radiation heat dissipation efficiency, effectively reduce the operating temperature of the internal quantum cascade laser 2, and improve the system stability and the consistency of the output laser power.

[0036] The working principle of this utility model is as follows: the two quantum cascade lasers 2 output lasers with a wavelength of 4.6μm, and the lasers of the two quantum cascade lasers 2 are collimated by two standard collimating lenses 4 respectively. The laser of the lower quantum cascade laser 2, after being collimated by the standard collimating lens 4, is adjusted from S-polarized light to P-polarized light by passing through a half-wave plate 5. At this time, the polarizer 6 selects the laser beam that is directly incident to the right to pass through.

[0037] The high-reflectivity mirror 7 refracts the laser emitted by the quantum cascade laser 2 on the rear side forward to the polarizer 6, and the polarizer 6 combines the two laser beams. At this time, the lasers of the two quantum cascade lasers 2 become coaxial and are emitted outward through the optical window 8.

[0038] The above description is merely a preferred embodiment of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model. Structures, devices, and operating methods not specifically described or explained in this utility model, unless otherwise specified or limited, shall be implemented using conventional methods in the field.

Claims

1. A device for enhancing the output power of a quantum cascade laser based on polarization beam combining, characterized in that: The system includes a base plate (3), on which two quantum cascade lasers (2) are fixed near the left side of the upper surface of the base plate (3), and a standard collimating lens (4) is fixed on the upper surface of the base plate (3) to the right of the two quantum cascade lasers (2). A polarizer (6) and a high-reflectivity mirror (7) are fixed on the upper surface of the base plate (3) to the right of the two standard collimating lenses (4). A half-wave plate (5) is provided between the polarizer (6) and the standard collimating lens (4) on the lower side. The high-reflectivity mirror (7) reflects light forward to the polarizer (6). The upper side of the base plate (3) is detachably fixed with a heat dissipation cover (1), and a light window (8) is provided on the right end face of the cover (1) at the position corresponding to the polarizer (6).

2. The device for enhancing the output power of a quantum cascade laser based on polarization beam combining according to claim 1, characterized in that: A support plate (11) is provided below both the polarizer (6) and the high reflectivity mirror (7). Two clamping plates (10) are fixed on the upper surface of the support plate (11) to clamp the polarizer (6) or the high reflectivity mirror (7) in the middle. The surfaces of the polarizer (6) and the high reflectivity mirror (7) are fixed with protrusions (9) near the lower edge.

3. The device for enhancing the output power of a quantum cascade laser based on polarization beam combining according to claim 1, characterized in that: A first fixing plate (45) is provided below the standard collimating lens (4). A positioning ring (44) for positioning and installing the standard collimating lens (4) is fixed on the upper side of the first fixing plate (45). A pressure ring (41) is provided on the upper side of the positioning ring (44) and pressed against the upper side of the standard collimating lens (4). One end of the pressure ring (41) and the positioning ring (44) are hinged together, and the other end of the pressure ring (41) and the positioning ring (44) are both fixed with a connecting plate (42). The two connecting plates (42) are fixedly connected by connecting screws (43).

4. The device for enhancing the output power of a quantum cascade laser based on polarization beam combining according to claim 1, characterized in that: The outer side of the half-wave plate (5) is fitted with a collar (51), and a second fixing plate (52) is fixed to the lower side of the collar (51).

5. The device for enhancing the output power of a quantum cascade laser based on polarization beam combining according to claim 1, characterized in that: The upper surface of the base plate (3) is fixed with a boss (33), and the base plate (3) is fixed with mounting plates (31) near the four corners. Multiple anchor screws (32) are installed on the front and rear sides of the boss (33).

6. The device for enhancing the output power of a quantum cascade laser based on polarization beam combining according to claim 5, characterized in that: The lower end of the cover (1) is fitted onto the outside of the boss (33), and multiple threaded holes (120) are provided on both the front and rear sides of the cover (1). The upper surface of the cover (1) is fixed with uniformly arranged heat sinks (110).

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