Fiber coupled output dual optical path laser isolator

Abstract

The application discloses an optical fiber coupling output double optical path laser isolation device, which comprises a fiber collimator, a polarization beam splitter, a first optical path, a second optical path and a focusing mirror; laser is collimated by the fiber collimator and then output to the polarization beam splitter, and the laser is separated into first linearly polarized light propagating along the first optical path and second linearly polarized light propagating along the second optical path; the first optical path is provided with a first 1 / 4 wave plate, and the second optical path is provided with a reflecting sheet, a 1 / 2 wave plate and a second 1 / 4 wave plate; the first linearly polarized light and the second linearly polarized light are output through the first optical path and the second optical path respectively and then reach a workpiece through the focusing mirror. The two linearly polarized lights obtained by polarization separation are transmitted through separate optical paths respectively, and wave plates and other optical elements are arranged in the two optical paths, so that the reflected light of the two lasers propagates in the two optical paths and cannot reach the fiber output port, laser isolation is realized, and the influence and damage of the reflected light on the fiber output port or the laser are solved.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to an isolation device for a fiber-coupled output dual-path laser. Background Technology

[0002] With the development of semiconductor laser technology, there are more and more applications that directly use high-power semiconductor lasers for processing. At the same time, optical fibers are widely accepted by the market due to their advantages in flexible processing.

[0003] When a laser beam propagates through an optical fiber, the light wave is continuously reflected between the inner walls of the fiber. Due to the different refractive indices of the optical fibers, light waves with different polarization directions experience phase delays during reflection, leading to interference between light waves of different polarization states. The result of this interference is the formation of circularly polarized light.

[0004] By separating the circularly polarized light output from the optical fiber into linearly polarized light with different polarization states, and then using two laser beams or merging them into one laser beam for processing applications, the processing accuracy can be improved, and the number of laser generators or other coupling devices can be reduced, thus reducing the overall size.

[0005] However, in laser processing applications, laser damage caused by reflected light has always been a core issue restricting the development of high-power semiconductor laser processing applications. Therefore, in dual-path laser applications, it is worth considering how to effectively solve the problem of internal equipment damage caused by laser reflection in the original path or through another optical path. Summary of the Invention

[0006] In response to the problems raised in the background technology, this invention proposes an isolation device for fiber-coupled dual-path lasers to solve the reflection problem that may occur between two laser beams with different polarization states during workpiece processing.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] An isolation device for a fiber-coupled output dual-path laser includes a fiber collimator, a polarizing beam splitter, a first optical path, a second optical path, and a focusing lens;

[0009] The fiber collimator is used to collimate the laser output from the fiber optic cable.

[0010] The polarization beam splitter separates the collimated laser output into two beams: a first linearly polarized beam and a second linearly polarized beam, which propagate at a 90° angle and have perpendicular polarization directions. The first linearly polarized beam propagates along the first optical path, and the second linearly polarized beam propagates along the second optical path.

[0011] The first optical path is provided with a first 1 / 4 wave plate, and the second optical path is provided with a 1 / 2 wave plate and a second 1 / 4 wave plate;

[0012] The second optical path is provided with a reflector, and the propagation direction of the second linearly polarized light after passing through the reflector is the same as the propagation direction of the first linearly polarized light;

[0013] The focusing lens is located at the output end of the first optical path and the second optical path, and the first linearly polarized light and the second linearly polarized light reach the workpiece after passing through the focusing lens.

[0014] Preferably, the polarizing beam splitter is a P-polarized light transmission S-polarized light reflection beam splitter or an S-polarized light transmission P-polarized light reflection beam splitter.

[0015] The linearly polarized light transmitted by the polarizing beam splitter propagates along the first optical path in the horizontal direction, and the linearly polarized light reflected by the polarizing beam splitter propagates along the second optical path in the vertical direction.

[0016] The reflector is positioned at a 45° angle to the incident light.

[0017] Preferably, the first quarter waveplate, the second quarter waveplate, and the half waveplate are transmission waveplates.

[0018] Preferably, the transmission direction of the first quarter-wave plate is different from the polarization direction of the first linearly polarized light; the transmission direction of the second quarter-wave plate is different from the polarization direction of the second linearly polarized light.

[0019] Preferably, the optical axis of the half-wave plate is at a 45° angle to the polarization direction of the second linearly polarized light.

[0020] Preferably, the polarizing beam splitter, the first quarter-wave plate, the second quarter-wave plate, and the half-wave plate are made of optical glass or fused silica.

[0021] Preferably, the working distance between the fiber collimator and the polarizing beam splitter is 1mm-200mm;

[0022] The working distance between the first quarter-wave plate and the polarizing beam splitter is 1mm-200mm;

[0023] The working distance between the second quarter waveplate and the half waveplate is 1mm-200mm.

[0024] Preferably, the center wavelength of the polarizing beam splitter is 400-2000 nm, the center wavelength of the first quarter wave plate is 400-2000 nm, the center wavelength of the second quarter wave plate is 400-2000 nm, and the center wavelength of the half wave plate is 400-2000 nm.

[0025] Compared with the prior art, one of the above technical solutions has the following beneficial effects:

[0026] This invention transmits two linearly polarized beams obtained by polarization separation through separate optical paths. A quarter-wave plate is placed in the first optical path of the first linearly polarized beam transmitted through a polarizing beam splitter, and a half-wave plate and a quarter-wave plate are placed in the second optical path of the second linearly polarized beam reflected by the polarizing beam splitter as polarization state adjustment components. This adjusts the polarization direction of the linearly polarized beams in both optical paths, ensuring that even if the laser light reflected from the workpiece is transmitted through the original optical path or other optical paths, the polarizing beam splitter, through the specific waveplates in the first and second optical paths, prevents the reflected laser light from reaching the fiber optic output port. This achieves isolation of the reflected laser light and solves the potential impact and damage that reflected light may cause to the fiber optic output port or the laser. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of one embodiment of the present invention;

[0028] Figure 2 This is a cross-sectional view of an embodiment of the present invention;

[0029] Figure 3 This is an optical path diagram of one embodiment of the present invention. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are 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 limitations on this invention.

[0032] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0033] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] The following is in conjunction with the appendix Figures 1 to 3 The technical solution of the present invention will be further illustrated through specific embodiments.

[0035] An isolation device for a fiber-coupled output dual-path laser includes a fiber collimator 2, a polarizing beam splitter 3, a first optical path 4, a second optical path 5, and a focusing lens 6;

[0036] The fiber collimator 2 is used to collimate the output of the laser 10 from the fiber optic cable.

[0037] The polarizing beam splitter 3 separates the collimated laser output into two beams: a first linearly polarized light 11 and a second linearly polarized light 12, which have a propagation direction at a 90° angle and perpendicular polarization directions. The first linearly polarized light 11 propagates along the first optical path 4, and the second linearly polarized light 12 propagates along the second optical path 5.

[0038] The first optical path 4 is provided with a first quarter wave plate 41, and the second optical path 5 is provided with a half wave plate 52 and a second quarter wave plate 51;

[0039] The second optical path 5 is provided with a reflector 53, and the propagation direction of the second linearly polarized light 12 after passing through the reflector 53 is the same as the propagation direction of the first linearly polarized light 11.

[0040] The focusing lens 6 is located at the output end of the first optical path 4 and the second optical path 5. The first linearly polarized light 11 and the second linearly polarized light 12 reach the workpiece after passing through the focusing lens 6.

[0041] This invention provides an isolation device for a fiber-coupled output dual-path laser. Specifically, this device is connected to the output end of an optical fiber to receive the laser 10 transmitted through the fiber. Figure 1 and Figure 2As shown, the fiber collimator 2 is used to collimate the laser 10 output from the fiber optic cable. A polarizing beam splitter 3 is positioned directly behind the fiber collimator 2. The collimated laser 10 remains circularly polarized. After passing through the polarizing beam splitter 3, the circularly polarized light is separated into two beams: a first linearly polarized beam 11 and a second linearly polarized beam 12 with mutually perpendicular polarization directions. The first linearly polarized beam 11 is obtained through transmission via the polarizing beam splitter 3, and the second linearly polarized beam 12 is obtained through reflection via the polarizing beam splitter 3. The first linearly polarized beam 11 propagates along the first optical path 4. After passing through the first quarter-wave plate 41, the polarization direction of the first linearly polarized beam 11 rotates by 45° before being output towards the output end of the first optical path 4. The second linearly polarized light 12 propagates along the second optical path 5. After passing through the half-wave plate 52 and the second quarter-wave plate 51, the polarization direction of the second linearly polarized light 12 is the same as that of the first linearly polarized light 11 after passing through the first quarter-wave plate 41. The second optical path 5 also includes a reflector 53 to change the propagation direction of the second linearly polarized light 12. The output direction of the second linearly polarized light 12 after reflection by the reflector 53 is the same as the output direction of the first linearly polarized light 11. After being output from their respective optical paths, the first linearly polarized light 11 and the second linearly polarized light 12 reach the workpiece after passing through the focusing lens 6. By adjusting the distance between the focusing lens 6 at the output end of the optical path and the workpiece, the specific position of the two polarized lights reaching the workpiece can be precisely adjusted.

[0042] During the processing of the workpiece by two laser beams, the laser beams may be reflected. The reflected path may return along the original optical path or along another optical path. For the first linearly polarized light 11, after passing through the first quarter-wave plate 41 in the first optical path 4, its polarization direction rotates by 45° before reaching the workpiece, and reflection may occur.

[0043] Scenario (1): Assume the first reflected light 11′ returns via the first optical path 4, and after passing through the first quarter-wave plate 41 again within the first optical path 4, the first reflected light 11′ rotates 45° again. At this time, the polarization direction of the first reflected light 11′ is perpendicular to the polarization direction of the first linearly polarized light 11, which is equivalent to the same polarization direction as the second linearly polarized light 12 formed by reflection by the polarizing beam splitter 3. Since the polarization direction of the first reflected light 11′ changes and is not the same as the transmission direction of the polarizing beam splitter 3, the reflected first linearly polarized light 11′ cannot return to the fiber output end through the polarizing beam splitter 3, thus avoiding damage to the reflected light.

[0044] Case (2): Assume that the first reflected light 11′ returns through the second optical path 5. After passing through the second 1 / 4 wave plate 51 and 1 / 2 wave plate 52 in the second optical path 5, the polarization direction of the first reflected light 11′ is the same as that of the first linearly polarized light 11 formed by the polarizing beam splitter 3. When it is reflected by the reflector 53 to the polarizing beam splitter 3, since the polarization direction of the first reflected light 11′ is the same as the transmission direction of the polarizing beam splitter 3, the first reflected light 11′ will directly pass through the polarizing beam splitter 3 and will not be reflected back to the fiber output end. Therefore, the damage of the reflected light can also be avoided.

[0045] Similarly, for the second linearly polarized light 12, after passing through the half-wave plate 52 and the second quarter-wave plate 51 in the second optical path 5, its polarization direction is rotated. Specifically, its polarization direction is the same as that of the first linearly polarized light 11 after passing through the first quarter-wave plate 41. After reaching the workpiece, reflection may also occur.

[0046] Case (3): Assuming the second reflected light 12′ returns through the second optical path 5, and passes through the second 1 / 4 wave plate 51 and 1 / 2 wave plate 52 again in the second optical path 5, the polarization direction of the second reflected light 12′ rotates again. At this time, the polarization direction of the second reflected light 12′ is the same as the transmission direction of the polarizing beam splitter 3. When the second reflected light 12′ is reflected by the reflector 53 to the polarizing beam splitter 3, it can be transmitted through the polarizing beam splitter 3 without being reflected into the fiber output end, thus avoiding damage to the reflected light.

[0047] Case (4): Assuming the second reflected light 12′ returns through the first optical path 4, since the polarization direction of the second linearly polarized light 12 after passing through the reflector 53, the second 1 / 4 wave plate and the 1 / 2 wave plate in the second optical path is consistent with the polarization direction of the first linearly polarized light 11 when it exits through the first optical path 4, the second reflected light 12′ at this time can be directly referred to Case (1). It can be seen that the second reflected light 12′ propagates through the first optical path 4 to the polarizing beam splitter 3. Since the polarization direction is different from the transmission direction, it cannot be transmitted through, thus avoiding damage to the reflected light.

[0048] This invention transmits two linearly polarized beams obtained by polarization separation through separate optical paths. A quarter-wave plate is placed in the first optical path of the first linearly polarized beam transmitted through a polarizing beam splitter, and a half-wave plate and a quarter-wave plate are placed in the second optical path of the second linearly polarized beam reflected by the polarizing beam splitter as polarization state adjustment components. This adjusts the polarization direction of the linearly polarized beams in both optical paths, ensuring that even if the laser light reflected from the workpiece is transmitted through the original optical path or other optical paths after laser processing, the specific wave plates in the first and second optical paths prevent it from reaching the fiber optic output port. This achieves isolation of the reflected laser light and solves the potential impact and damage to the fiber optic output port caused by the reflected light.

[0049] Furthermore, the polarizing beam splitter 3 is a P-polarized light transmission S-polarized light reflection beam splitter or an S-polarized light transmission P-polarized light reflection beam splitter.

[0050] The linearly polarized light transmitted by the polarizing beam splitter 3 propagates along the first optical path 4 in the horizontal direction, and the linearly polarized light reflected by the polarizing beam splitter 3 propagates along the second optical path 5 in the vertical direction.

[0051] The reflector 53 is positioned at a 45° angle to the incident light.

[0052] If the polarizing beam splitter 3 is a P-polarized light transmission S-polarized light reflection beam splitter, then the laser 10 output from the optical fiber, after being collimated by the optical fiber collimator 2, is separated by the polarizing beam splitter 3 into a first linearly polarized light 11 transmitted horizontally (P-light) and a second linearly polarized light 12 reflected vertically (S-light). Similarly, if the polarizing beam splitter 3 is an S-polarized light transmission P-polarized light reflection beam splitter, then the first linearly polarized light 11 is S-light, and the second linearly polarized light 12 is P-light. The working principle of this invention will be detailed below using the example of a P-polarized light transmission S-polarized light reflection beam splitter 3.

[0053] The P-beam, acting as the first linearly polarized light 11, passes through the first quarter-wave plate 41 in the first optical path 4. The emitted light then rotates 45° and reaches the workpiece after passing through the focusing lens 6. If there is reflected light, the first reflected light 11′ may return via the first optical path 4 or the second optical path 5. If the first reflected light 11′ returns via the first optical path 4, it will pass through the first quarter-wave plate 41 again and rotate 45°. At this point, the first reflected light 11′ becomes the S-beam and continues to propagate towards the polarizing beam splitter 3. Since the polarization direction of the S-beam is perpendicular to the transmission direction of the polarizing beam splitter 3, the S-beam cannot pass through the polarizing beam splitter 3. Therefore, the first reflected light 11′ is isolated by the polarizing beam splitter 3 and cannot pass through, thus achieving isolation of the reflected light. If the first reflected light 11′ is reflected back through the second optical path 5, then the first reflected light 11′ will be rotated by 45° by the second 1 / 4 wave plate 51. At this time, the first reflected light 11′ becomes S light. After passing through the 1 / 2 wave plate 52, the S light becomes P light again and continues to be transmitted towards the reflector 53. After being reflected by the reflector 53, it reaches the polarizing beam splitter 3. Since the polarization direction of the P light is the same as the transmission direction of the polarizing beam splitter 3, the first reflected light 11′ can pass through the polarizing beam splitter 3 and will not be reflected into the optical fiber output port, thus achieving isolation of the reflected light.

[0054] S-beam, acting as the second linearly polarized light 12, propagates in the second optical path 5, which is divided into a vertical and a horizontal section. The reflector 53 changes the propagation direction of the second linearly polarized light 12, obtained by reflection from the polarizing beam splitter 3, from vertical to horizontal. After reflection by the reflector 53, the propagation direction of the second linearly polarized light 12 is the same as that of the first linearly polarized light 11. In the horizontal section of the second optical path 5, the second linearly polarized light 12 becomes P-beam after passing through the half-wave plate 52. After passing through the second quarter-wave plate 51, its polarization direction is rotated by 45° before reaching the workpiece after passing through the focusing lens 6. It is noteworthy that the polarization direction of the second linearly polarized light 12 after passing through the half-wave plate 52 and the second quarter-wave plate 51 is the same as the polarization direction of the first linearly polarized light 11 after passing through the first quarter-wave plate 41 in the first optical path 4. Therefore, the reflection of the second linearly polarized light 12 after it propagates to the workpiece through the second optical path 5, and the principle of the second reflected light 12′ returning through the first optical path 4 or the second optical path 5, are the same as the principle of the first reflected light 11′, and will not be repeated here.

[0055] It is worth noting that in the second optical path 5, there is no restriction on the order in which the half-wave plate 52 and the second quarter-wave plate 51 are set. The specific order in which the linearly polarized light passes through the half-wave plate and the quarter-wave plate does not affect the properties of the final output polarized light.

[0056] Furthermore, the first quarter waveplate 41, the second quarter waveplate 51, and the half waveplate 52 are transmission waveplates. Only transmission waveplates can ensure that linearly polarized light passes through the optical path and achieves straight-line propagation.

[0057] Furthermore, the transmission direction of the first quarter-wave plate is different from the polarization direction of the first linearly polarized light; the transmission direction of the second quarter-wave plate is different from the polarization direction of the second linearly polarized light.

[0058] Ensure the effectiveness of the optical isolation component in the first optical path and the optical polarization state conversion component in the second optical path. If the polarization direction of linearly polarized light is the same as the transmission direction of the quarter-wave plate, the polarization of the light will not change after passing through the quarter-wave plate. This is because the quarter-wave plate has a delay effect on light with a specific polarization direction, but when the polarization direction of linearly polarized light is the same as the transmission direction of the wave plate, the effect of the wave plate is equivalent to none, and the polarization state of the light will not change.

[0059] The optical axis of the half-wave plate 52 is at a 45° angle to the polarization direction of the second linearly polarized light 12.

[0060] The optical axis of the half-wave plate 52 is at a 45° angle to the polarization direction of the second linearly polarized light 12, which ensures that the polarization direction of the second linearly polarized light 12 is deflected by 90°.

[0061] Furthermore, the polarizing beam splitter 3, the first quarter wave plate 41, the second quarter wave plate 51, and the half wave plate 52 are made of optical glass or fused silica.

[0062] Optical glass or fused silica both have superior optical properties, heat resistance, and high stability, making them suitable for the transmission, focusing, and guidance of lasers in laser fiber-coupled outputs.

[0063] Preferably, the working distance between the fiber collimator 2 and the polarizing beam splitter 3 is 1mm-200mm;

[0064] The working distance between the first quarter-wave plate 41 and the polarizing beam splitter 3 is 1mm-200mm;

[0065] The working distance between the second quarter wave plate 51 and the half wave plate 52 is 1mm-200mm.

[0066] Preferably, the center wavelength of the polarizing beam splitter 3 is 400-2000 nm, the center wavelength of the first quarter wave plate 41 is 400-2000 nm, the center wavelength of the second quarter wave plate 51 is 400-2000 nm, and the center wavelength of the half wave plate 52 is 400-2000 nm.

[0067] The polarizing beam splitter 3 has a center wavelength of 400-2000nm, making it an ideal broadband, wide-field-of-view polarizing beam splitter with high transmittance and high stability. The center wavelengths of the first quarter-wave plate 41, the second quarter-wave plate 51, and the half-wave plate 52 are also 400-2000nm, indicating that the waveplates have a wide operating wavelength range, covering the visible and near-infrared bands, making them suitable for optical systems of different wavelengths.

[0068] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. An isolation device for a fiber-coupled output dual-path laser, characterized in that: Includes fiber optic collimator, polarizing beam splitter, first optical path, second optical path, and focusing lens; The fiber collimator is used to collimate the laser output from the fiber optic cable. The polarization beam splitter separates the collimated laser output into two beams: a first linearly polarized beam and a second linearly polarized beam, which propagate at a 90° angle and have perpendicular polarization directions. The first linearly polarized beam propagates along the first optical path, and the second linearly polarized beam propagates along the second optical path. The first optical path is provided with a first 1 / 4 wave plate, and the second optical path is provided with a 1 / 2 wave plate and a second 1 / 4 wave plate; The transmission direction of the first quarter-wave plate is different from the polarization direction of the first linearly polarized light; the transmission direction of the second quarter-wave plate is different from the polarization direction of the second linearly polarized light. The second optical path is provided with a reflector, and the propagation direction of the second linearly polarized light after passing through the reflector is the same as the propagation direction of the first linearly polarized light; The focusing lens is located at the output end of the first optical path and the second optical path, and the first linearly polarized light and the second linearly polarized light reach the workpiece after passing through the focusing lens; The optical axis of the half-wave plate forms a 45° angle with the polarization direction of the second linearly polarized light.

2. The fiber-coupled output dual-path laser isolation device according to claim 1, characterized in that: The polarization beam splitter is either a P-polarized light transmission S-polarized light reflection beam splitter or an S-polarized light transmission P-polarized light reflection beam splitter. The linearly polarized light transmitted by the polarizing beam splitter propagates along the first optical path in the horizontal direction, and the linearly polarized light reflected by the polarizing beam splitter propagates along the second optical path in the vertical direction. The reflector is positioned at a 45° angle to the incident light.

3. The fiber-coupled output dual-path laser isolation device according to claim 1, characterized in that: The first quarter waveplate, the second quarter waveplate, and the half waveplate are transmission waveplates.

4. The fiber-coupled output dual-path laser isolation device according to claim 1, characterized in that: the polarizing beam splitter, the first quarter-wave plate, the second quarter-wave plate and the half-wave plate are made of optical glass or fused silica.

5. The fiber-coupled output dual-path laser isolation device according to claim 1, characterized in that: the working distance between the fiber collimator and the polarization beam splitter is 1mm-200mm; The working distance between the first quarter-wave plate and the polarizing beam splitter is 1mm-200mm; The working distance between the second quarter waveplate and the half waveplate is 1mm-200mm.

6. The fiber-coupled output dual-path laser isolation device according to claim 1, characterized in that: the center wavelength of the polarizing beam splitter is 400-2000nm, the center wavelength of the first quarter-wave plate is 400-2000nm, the center wavelength of the second quarter-wave plate is 400-2000nm, and the center wavelength of the half-wave plate is 400-2000nm.

Images