Single-layer and double-layer multi-pass pump optical systems

Abstract

The present invention provides a single-layer and double-layer multi-pass pumping optical system to address the technical problem that the internal gain medium has a high single-pass absorption of pump light and the laser head with a low requirement for the number of pump laser passes cannot be well adapted to existing pump optical systems. The single-layer multi-pass pumping optical system provided by the present invention, through the positional relationship design between multiple reflectors, the laser head and the parabolic reflector, allows the pump laser to travel back and forth to the laser head multiple times. At the same time, the double-layer multi-pass pumping optical system provided by the present invention divides the larger number of reflectors into first reflectors and second reflectors, and arranges them into two inner and outer circles. At the same time, the laser head and the parabolic reflector cooperate to allow the pump laser to travel back and forth to the laser head multiple times. The laser head effectively absorbs the pump laser through the gain medium inside the laser head, providing more efficient multi-pass energy storage for the laser head. The optical path design is simple and easy to operate.

Description

Technical Field

[0001] The invention relates to a laser head, in particular to a single-layer and double-layer multi-pass pumping optical system. Background Art

[0002] High-average-power ultrafast lasers have important applications in ultraprecision machining, biomedicine, and scientific research. Currently, only thin-disk laser technology can simultaneously support high average power and high pulse energy output. Mainstream heat-sink thin-disk laser heads require complex pump optics to improve pumping efficiency due to the extremely thin thickness of the thin-disk gain medium and the minimal absorption of pump light per shot.

[0003] Chinese patent CN2023106337037 discloses a transmission / reflection laser head, whose internal gain medium has a high single-shot absorption of pump light and a low requirement for the pump laser path number, but this laser head cannot adapt well to existing pump optical systems. Summary of the Invention

[0004] The purpose of the present invention is to provide a single-layer and double-layer multi-pass pump optical system to solve the technical problem that the laser head with a high single-pass absorption of pump light by the internal gain medium and a low requirement for the number of pump laser passes cannot adapt well to the existing pump optical system.

[0005] In order to achieve the above objectives, the technical solutions provided by the present invention are as follows:

[0006] A single-layer multi-pass pumping optical system is characterized in that it comprises 2n reflectors, a laser head coaxially arranged in sequence, a reflector mounting frame and a parabolic reflector, where n is greater than or equal to 2;

[0007] The reflector mounting frame is provided with a light hole, a light inlet and a light outlet in the axial direction; the light hole is located at the center of the reflector mounting frame;

[0008] 2n reflectors are arranged on an end surface of a reflector mounting frame close to the parabolic reflector, and the reflective surfaces of the reflectors are arranged tilted relative to the reflector mounting frame; the 2n reflectors are evenly divided into two groups, and the n reflectors of the first group, the n reflectors of the second group, the light outlet, and the light inlet are evenly distributed along the same circumference in sequence;

[0009] The reflection surfaces of the i-th reflector in the first group and the i-th reflector in the second group have the same inclination angle, and the reflection surfaces of the two are arranged opposite to each other, i = 1, 2, ..., n;

[0010] The reflecting surface of the laser head is located at the focal position of the parabolic reflector;

[0011] The light inlet is located on the incident light path of the pump laser. The incident light of the pump laser enters the parabolic reflector through the light inlet, and then travels back and forth n times through the parabolic reflector, the laser head, the parabolic reflector, the i-th reflector of the second group, the i-th reflector of the first group, and the parabolic reflector, and then is reflected by the laser head and the parabolic reflector before being emitted through the light outlet. The value of i starts from 1 and increases by 1 every time it travels back and forth.

[0012] The sum of the transmission distances of the pump laser from the parabolic reflector to the i-th reflector in the second group, the i-th reflector in the second group to the i-th reflector in the first group, and the i-th reflector in the first group to the parabolic reflector is equal to twice the focal length of the parabolic reflector.

[0013] Furthermore, a zero-degree reflector is provided on the light outlet, for allowing the pump laser to be reflected by the zero-degree reflector and then returned along the original transmission path, so that the number of times the laser head absorbs the pump laser is doubled;

[0014] The transmission distance of the pump laser from the parabolic reflector to the zero-degree reflector is equal to the focal length of the parabolic reflector.

[0015] Furthermore, the laser head is a transmissive laser head or a reflective laser head.

[0016] Furthermore, the inclination angles of the reflecting surfaces of the 2n reflecting mirrors are all 45°.

[0017] Furthermore, n=4.

[0018] At the same time, the present invention also provides another double-layer multi-pass pumping optical system, which is special in that it includes 2p first reflectors, 2q second reflectors, a laser head coaxially arranged in sequence, a reflector mounting frame and a parabolic reflector, p≥2, q≥2, p≥q;

[0019] The reflector mounting frame is provided with a light hole, a light inlet and a light outlet in the axial direction; the light hole is located at the center of the reflector mounting frame;

[0020] The 2p first reflectors and the 2q second reflectors are all arranged on an end surface of a reflector mounting frame close to the parabolic reflector, and the reflective surfaces of the first reflectors and the second reflectors are both inclined relative to the reflector mounting frame; the lowest point of the reflective surface of the first reflector is higher than the highest point of the reflective surface of the second reflector;

[0021] Divide the 2p first reflectors and the 2q second reflectors into two groups, respectively. The p first reflectors in the first group, the p first reflectors in the second group, the light entrance, and the one second reflector in the first group are uniformly distributed along the same circumference in sequence to form a first ring position. The q-1 second reflectors in the first group, the q second reflectors in the second group, and the light exit are uniformly distributed along the same circumference in the opposite direction to form a second ring position. The second ring position is located inner to the first ring position, and the light entrance and the light exit are located at the same radial position of the first and second ring positions.

[0022] The reflection surfaces of the j-th first reflector in the first group and the j-th first reflector in the second group have the same inclination angle, and the two reflection surfaces are arranged opposite to each other, j = 1, 2, ..., p; the reflection surfaces of the k-th second reflector in the first group and the k-th second reflector in the second group have the same inclination angle, and the two reflection surfaces are arranged opposite to each other, k = 1, 2, ..., q;

[0023] The reflecting surface of the laser head is located at the focal position of the parabolic reflector;

[0024] The light inlet is located on the incident light path of the pump laser. The incident light of the pump laser is incident on the parabolic reflector through the light inlet. The pump laser passes through the parabolic reflector, the laser head, the parabolic reflector, the j-th first reflector of the second group, the j-th first reflector of the first group, and the parabolic reflector for p round trips, and then passes through the parabolic reflector, the laser head, the parabolic reflector, the k-th second reflector of the first group, the k-th second reflector of the second group, and the parabolic reflector for q round trips, and then passes through the laser head and the parabolic reflector before being emitted through the light outlet. The value of j starts from 1 and increases by 1 for each round trip; the value of k starts from 1 and increases by 1 for each round trip.

[0025] The sum of the transmission distances of the pump laser from the parabolic reflector to the j-th first reflector of the second group, the j-th first reflector of the second group to the j-th first reflector of the first group, and the j-th first reflector of the first group to the parabolic reflector is equal to twice the focal length of the parabolic reflector;

[0026] The sum of transmission distances of the pump laser from the parabolic reflector to the kth second reflector in the second group, the kth second reflector in the second group to the kth second reflector in the first group, and the kth second reflector in the first group to the parabolic reflector is equal to twice the focal length of the parabolic reflector.

[0027] Furthermore, a zero-degree reflector is provided on the light outlet, for allowing the pump laser to be reflected by the zero-degree reflector and then returned along the original transmission path, so that the number of times the laser head absorbs the pump laser is doubled;

[0028] The transmission distance of the pump laser from the parabolic reflector to the zero-degree reflector is equal to the focal length of the parabolic reflector.

[0029] Furthermore, the laser head is a transmissive laser head or a reflective laser head.

[0030] Furthermore, the inclination angle of the reflecting surfaces of the 2p first reflecting mirrors is 45°;

[0031] The inclination angle of the reflecting surfaces of the 2q second reflecting mirrors is 45°.

[0032] Furthermore, p=6, q=4.

[0033] The beneficial effects of the present invention compared to the prior art are as follows:

[0034] 1. The present invention provides a single-layer multi-pass pumping optical system. Through multiple reflectors, a laser head and a parabolic reflector, the pump laser can be sent back and forth to the laser head multiple times. The gain medium inside the laser head enables the laser head to effectively absorb the pump laser, providing more efficient multi-pass energy storage for the laser head. The optical path design is simple and easy to operate.

[0035] 2. The present invention provides a double-layer multi-pass pumping optical system, which divides a large number of reflectors into a first reflector and a second reflector, and arranges them into two inner and outer circles. At the same time, it cooperates with a laser head and a parabolic reflector to make the pump laser travel back and forth to the laser head multiple times, and realizes the laser head's effective absorption of the pump laser for multiple passes through the gain medium inside the laser head.

[0036] 3. The single-layer and double-layer multi-pass pumping optical system of the present invention is provided with a zero-degree reflector at the light outlet. The transmission distance of the pump laser from the parabolic reflector to the zero-degree reflector is equal to the focal length of the parabolic reflector. It is used to make the pump laser return along the original transmission path after being reflected by the zero-degree reflector, so that the number of passes of the laser head to absorb the pump laser is increased by 1 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the structure of a single-layer multi-pass pumping optical system embodiment 1 of the present invention. Figure 1 ;

[0038] Figure 2 for Figure 1 A longitudinal cross-sectional view of

[0039] Figure 3 Schematic diagram of the distribution of eight reflectors, light outlets, and light inlets on a reflector mounting frame in Example 1 of the present invention;

[0040] Figure 4 This is a schematic diagram of the structure of a double-layer multi-pass pumping optical system embodiment 3 of the present invention. Figure 1 ;

[0041] Figure 5 for Figure 4 Longitudinal cross-sectional view.

[0042] The specific reference numerals are as follows:

[0043] 1-reflector mounting frame, 11-light hole, 12-light inlet, 13-light outlet; 2-laser head; 3-parabolic reflector. DETAILED DESCRIPTION

[0044] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] Example 1

[0046] like Figure 1 、 Figure 2 As shown, a single-layer multi-pass pumping optical system includes eight reflectors, a coaxially arranged laser head 2, a reflector mounting frame 1, and a parabolic reflector 3. The reflector mounting frame 1 is axially defined with a light hole 11, a light inlet 12, and a light outlet 13. The light hole 11 is located at the center of the reflector mounting frame 1.

[0047] Eight reflectors are arranged on one end face of the reflector mounting frame 1 close to the parabolic reflector 3, and the reflective surfaces of the reflectors are arranged tilted relative to the reflector mounting frame 1. The eight reflectors are divided into two groups. The four reflectors in the first group are respectively marked as reflector A1, reflector A2, reflector A3 and reflector A4, and the four reflectors in the second group are respectively marked as reflector B1, reflector B2, reflector B3 and reflector B4. Figure 3 As shown, reflector A1, reflector A2, reflector A3, reflector A4, reflector B1, reflector B2, reflector B3, reflector B4, light outlet 13, and light inlet 12 are uniformly distributed counterclockwise along the same circumference. That is, reflector A1 and reflector B2, reflector A2 and reflector B3, reflector A3 and reflector B4, reflector A4 and light outlet 13, and reflector B1 and light inlet 12 are symmetrical about the center point of the reflector mounting frame 1. In other embodiments of the present invention, the eight reflectors, light outlet 13, and light inlet 12 may also be uniformly distributed clockwise along the same circumference.

[0048] The reflective surfaces of reflectors A1 and B1, reflectors A2 and B2, reflectors A3 and B3, and reflectors A4 and B4 are arranged opposite each other, and the reflective surfaces of the two oppositely arranged reflectors have the same inclination angle. Preferably, in this embodiment, the reflective surface inclination angles of the eight reflectors are all 45°.

[0049] The reflective surface of laser head 2 is located at the focal point of parabolic reflector 3. Laser head 2 can be a transmissive laser head or a reflective laser head. Light inlet 12 is located on the incident optical path of the pump laser. The reflective surface of parabolic reflector 3 is located on the incident optical path of the pump laser and is also located on the reflected optical path of the reflective surfaces of laser head 2, reflector A1, reflector A2, reflector A3, and reflector A4.

[0050] The reflecting surface of reflector A1 is located on the reflecting light path of reflector B1, the reflecting surface of reflector A2 is located on the reflecting light path of reflector B2, the reflecting surface of reflector A3 is located on the reflecting light path of reflector B3, and the reflecting surface of reflector A4 is located on the reflecting light path of reflector B4. The reflecting surface of the reflector B1 is located on the optical path after the pump laser is incident through the light input port 12 and is reflected in sequence by the parabolic reflector 3, the laser head 2, and the parabolic reflector 3. The reflecting surface of the reflector B2 is located on the optical path after the pump laser is reflected in sequence by the reflector A1, the parabolic reflector 3, the laser head 2, and the parabolic reflector 3. The reflecting surface of the reflector B3 is located on the optical path after the pump laser is reflected in sequence by the reflector A2, the parabolic reflector 3, the laser head 2, and the parabolic reflector 3. The reflecting surface of the reflector B4 is located on the optical path after the pump laser is reflected in sequence by the reflector A3, the parabolic reflector 3, the laser head 2, and the parabolic reflector 3. The light output port 13 is located on the optical path after the pump laser is reflected in sequence by the reflector A4, the parabolic reflector 3, the laser head 2, and the parabolic reflector 3.

[0051] In order to ensure that the pump laser presents an ideal laser spot effect in the laser head 2, the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the reflector B1, the reflector B1 to the reflector A1, and the reflector A1 to the parabolic reflector 3; the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the reflector B2, the reflector B2 to the reflector A2, and the reflector A2 to the parabolic reflector 3; the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the reflector B3, the reflector B3 to the reflector A3, and the reflector A3 to the parabolic reflector 3; and the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the reflector B4, the reflector B4 to the reflector A4, and the reflector A4 to the parabolic reflector 3 are all equal to twice the focal length of the parabolic reflector 3.

[0052] The working principle of the single-layer multi-pass pumping optical system of the pump laser is as follows:

[0053] The shaped and homogenized pump laser is incident on the reflective surface of the parabolic reflector 3 through the light inlet 12, and then is reflected by the parabolic reflector 3 and incident on the reflective surface of the laser head 2 through the light hole 11 of the reflector mounting frame 1. Then, it is reflected by the laser head 2 to the reflective surface of the parabolic reflector 3, and then reflected by the parabolic reflector 3 to the reflective surface of the reflector B1, and then reflected by the reflector B1 to the reflective surface of the reflector A1, completing the first absorption of the pump laser by the laser head 2; the reflector A1 receives the pump laser. The pump laser is reflected to the reflecting surface of parabolic reflector 3, and then reflected to the reflecting surface of laser head 2 by parabolic reflector 3. Then, it is reflected to the reflecting surface of parabolic reflector 3 by laser head 2, and then reflected to the reflecting surface of reflector B2 by parabolic reflector 3, and then reflected to the reflecting surface of reflector A2 by reflector B2, thus completing the second absorption of pump laser by laser head 2. Reflector A2 reflects the received pump laser to the reflecting surface of parabolic reflector 3, and then reflects to the reflecting surface of laser head 2 by parabolic reflector 3. 2, and then reflected by laser head 2 to the reflecting surface of parabolic reflector 3, and then reflected by parabolic reflector 3 to the reflecting surface of reflector B3, and then reflected by reflector B3 to the reflecting surface of reflector A3, completing the third-pass absorption of pump laser by laser head 2; reflector A3 reflects the received pump laser to the reflecting surface of parabolic reflector 3, and then reflected by parabolic reflector 3 to the reflecting surface of laser head 2, and then reflected by laser head 2 to the reflecting surface of parabolic reflector 3, and then reflected by parabolic reflector 3 to the reflecting surface of reflector B3. Parallel reflector 3 reflects the pump laser onto the reflective surface of reflector B4, which then reflects it onto the reflective surface of reflector A4 via reflector B4, completing the fourth-pass absorption of the pump laser by laser head 2. Mirror A4 reflects the received pump laser onto the reflective surface of parabolic reflector 3, which then reflects it onto the reflective surface of laser head 2 via parabolic reflector 3. It is then reflected onto the reflective surface of parabolic reflector 3 via laser head 2, and then onto the reflective surface of parabolic reflector 3 via parabolic reflector 3, and finally onto light outlet 13 via parabolic reflector 3, completing the fifth-pass absorption of the pump laser by laser head 2. The single-layer multi-pass pump optical system of the present invention enables effective absorption of the pump laser by laser head 2, providing more efficient energy storage.

[0054] In this embodiment, the light inlet 12 and the light outlet 13 can be used interchangeably, in which case the transmission path of the pump laser is reversed. The number of reflectors can be increased or decreased by multiples of 2, which will increase or decrease the absorption path of the pump laser by the laser head 2 accordingly.

[0055] Example 2

[0056] The structure of the second embodiment is the same as that of the first embodiment, with the only difference being that a zero-degree reflector is provided on the light outlet 13 of the second embodiment. The transmission distance of the pump laser from the parabolic reflector 3 to the zero-degree reflector is equal to the focal length of the parabolic reflector 3, so that the pump laser is reflected by the zero-degree reflector and then returns along the original transmission path, thereby doubling the number of times the laser head 2 absorbs the pump laser.

[0057] Example 3

[0058] like Figure 4 、 Figure 5 As shown, a double-layer multi-pass pumping optical system includes twelve first reflectors, eight second reflectors, a coaxially arranged laser head 2, a reflector mounting frame 1, and a parabolic reflector 3. The reflector mounting frame 1 is axially defined with a light hole 11, a light inlet 12, and a light outlet 13. The light hole 11 is located at the center of the reflector mounting frame 1.

[0059] The twelve first reflectors and the eight second reflectors are all arranged on an end surface of the reflector mounting frame 1 close to the parabolic reflector 3 , and the reflecting surfaces of the first reflectors and the second reflectors are both tilted relative to the reflector mounting frame 1 .

[0060] The twelve first reflectors are divided into two groups, and the six first reflectors in the first group are respectively recorded as first reflector C1, first reflector C2, first reflector C3, first reflector C4, first reflector C5, and first reflector C6, and the six first reflectors in the second group are respectively recorded as first reflector D1, first reflector D2, first reflector D3, first reflector D4, first reflector D5, and first reflector D6; the eight second reflectors are also divided into two groups, and the four second reflectors in the first group are respectively recorded as second reflector E1, second reflector E2, second reflector E3, and second reflector E4, and the four second reflectors in the second group are respectively recorded as second reflector F1, second reflector F2, second reflector F3, and second reflector F4. The first reflector C1, the first reflector C2, the first reflector C3, the first reflector C4, the first reflector C5, the first reflector C6, the first reflector D1, the first reflector D2, the first reflector D3, the first reflector D4, the first reflector D5, the first reflector D6, the light entrance 12 and the second reflector F1 are evenly distributed counterclockwise along the same circumference, and the first reflector C1 and the first reflector D2, the first reflector C2 and the first reflector D3, the first reflector C3 and the first reflector D4, the first reflector C4 and the first reflector D5, the first reflector C5 and the first reflector D6, the first reflector C6 and the light entrance 12, the first reflector D1 and the second reflector F1 are respectively symmetrical about the center point of the reflector mounting frame 1. The second reflector E1, the second reflector E2, the second reflector E3, the second reflector E4, the second reflector F2, the second reflector F3, the second reflector F4, and the light outlet 13 are evenly distributed along the same circle in a clockwise direction. Then, the second reflector E1 and the second reflector F2, the second reflector E2 and the second reflector F3, the second reflector E3 and the second reflector F4, and the second reflector E4 and the light outlet 13 are symmetrical about the center point of the reflector mounting frame 1.

[0061] The thirteen reflectors and the light inlet 12 arranged counterclockwise are denoted as the first ring position, and the seven reflectors and the light outlet 13 arranged clockwise are denoted as the second ring position, with the second ring position being located within the first ring position. To avoid optical path interference, the lowest point of the reflective surface of the first reflector is higher than the highest point of the reflective surface of the second reflector. At the same time, the light inlet 12 and the light outlet 13 need to be located at the same radial position in the first and second ring positions, and the arrangement order in the first and second ring positions needs to be opposite, so that the reflected light from the second reflector F1 is smoothly transmitted from above the light outlet 13 to the second reflector E1, avoiding interference and obstruction of the reflected light from the second reflector F1 by other reflectors. In other embodiments of the present invention, the thirteen reflectors and the light inlet 12 on the first ring position can also be evenly distributed clockwise along the same circumference, and the seven reflectors and the light outlet 13 on the second ring position need to be evenly distributed clockwise along the same circumference.

[0062] The reflective surfaces of the first reflector C1 and the first reflector D1, the first reflector C2 and the first reflector D2, the first reflector C3 and the first reflector D3, the first reflector C4 and the first reflector D4, the first reflector C5 and the first reflector D5, the first reflector C6 and the first reflector D6, the second reflector E1 and the second reflector F1, the second reflector E2 and the second reflector F2, the second reflector E3 and the second reflector F3, and the second reflector E4 and the second reflector F4 are respectively arranged opposite to each other, and the reflective surfaces of the two oppositely arranged reflectors have the same inclination angle. Preferably, in this embodiment, the reflective surface inclination angles of the twenty reflectors are all 45°.

[0063] The laser head 2 and the parabolic reflector 3 are located on either side of the reflector mounting frame 1, respectively. The reflective surface of the laser head 2 is located at the focal point of the parabolic reflector 3. The laser head 2 can be a transmissive laser head or a reflective laser head. The light inlet 12 is located on the incident optical path of the pump laser. The reflective surface of the parabolic reflector 3 is located on the incident optical path of the pump laser and is also located on the reflective optical path of the laser head 2, the first reflector C1, the first reflector C2, the first reflector C3, the first reflector C4, the first reflector C5, the first reflector C6, the second reflector E1, the second reflector E2, the second reflector E3, and the reflective surface of the second reflector E4.

[0064] The reflecting surface of the first reflector D1 is located on the reflecting light path of the first reflector C1, the reflecting surface of the first reflector D2 is located on the reflecting light path of the first reflector C2, the reflecting surface of the first reflector D3 is located on the reflecting light path of the first reflector C3, the reflecting surface of the first reflector D4 is located on the reflecting light path of the first reflector C4, the reflecting surface of the first reflector D5 is located on the reflecting light path of the first reflector C5, and the reflecting surface of the first reflector D6 is located on the reflecting light path of the first reflector C6; the reflecting surface of the first reflector C6 is located on the reflecting light path of the pump laser after it is incident through the light inlet 12 and is reflected by the parabolic reflector 3, the laser head 2, and the parabolic reflector 3 in sequence, the reflecting surface of the first reflector C5 is located on the reflecting light path of the pump laser after it is reflected by the first reflector D6, the parabolic reflector 3. The reflecting surface of the first reflecting mirror C4 is located on the reflected light path after the pump laser is reflected by the first reflecting mirror D5, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3 in sequence. The reflecting surface of the first reflecting mirror C3 is located on the reflected light path after the pump laser is reflected by the first reflecting mirror D4, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3 in sequence. The reflecting surface of the first reflecting mirror C2 is located on the reflected light path after the pump laser is reflected by the first reflecting mirror D3, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3 in sequence. The reflecting surface of the first reflecting mirror C1 is located on the reflected light path after the pump laser is reflected by the first reflecting mirror D2, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3 in sequence.

[0065] The reflecting surface of the second reflecting mirror E1 is located on the reflecting light path of the second reflecting mirror F1, the reflecting surface of the second reflecting mirror E2 is located on the reflecting light path of the second reflecting mirror F2, the reflecting surface of the second reflecting mirror E3 is located on the reflecting light path of the second reflecting mirror F3, and the reflecting surface of the second reflecting mirror E4 is located on the reflecting light path of the second reflecting mirror F4; the reflecting surface of the second reflecting mirror F1 is located on the reflecting light path of the pump laser after it is reflected by the first reflecting mirror D1, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3 in sequence, and the reflecting surface of the second reflecting mirror F2 is located on the reflecting light path of the pump laser after it is reflected by the second reflecting mirror E1, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3 in sequence. The reflecting surface of the second reflecting mirror F3 is located on the reflected light path after the pump laser is reflected by the second reflecting mirror E2, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3. The reflecting surface of the second reflecting mirror F4 is located on the reflected light path after the pump laser is reflected by the second reflecting mirror E3, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3. The light outlet 13 is located on the reflected light path after the pump laser is reflected by the second reflecting mirror E1, the parabolic reflecting mirror 3, the laser head 2, and the parabolic reflecting mirror 3.

[0066] In order to ensure that the pump laser presents an ideal laser spot effect in the laser head 2, the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the first reflector D1, the first reflector D1 to the first reflector C1, and the first reflector C1 to the parabolic reflector 3; the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the first reflector D2, the first reflector D2 to the first reflector C2, and the first reflector C2 to the parabolic reflector 3; the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the first reflector D3, the first reflector D3 to the first reflector C3, and the first reflector C3 to the parabolic reflector 3; the sum of the transmission distances of the pump laser from the parabolic reflector 3 to the first reflector D4, the first reflector D4 to the first reflector C4, and the first reflector C4 to the parabolic reflector 3; the first reflector D5, the first reflector D5 to the first reflector C4, and the first reflector C4 to the parabolic reflector 3. The sum of the transmission distances from the first reflector C5, the first reflector C5 to the parabolic reflector 3, the sum of the transmission distances from the first reflector D6, the first reflector D6 to the first reflector C6, the first reflector C6 to the parabolic reflector 3, the second reflector F1, the second reflector F1 to the second reflector E1, and the second reflector E1 to the parabolic reflector 3, the sum of the transmission distances from the second reflector F2, the second reflector F2 to the second reflector E2, and the second reflector E2 to the parabolic reflector 3, the sum of the transmission distances from the second reflector F3, the second reflector F3 to the second reflector E3, and the second reflector E3 to the parabolic reflector 3, and the sum of the transmission distances from the second reflector F4, the second reflector F4 to the second reflector E4, and the second reflector E4 to the parabolic reflector 3 are all equal to twice the focal length of the parabolic reflector 3.

[0067] The working principle of the double-layer multi-pass pumping optical system of the pump laser is as follows:

[0068] After the shaped and homogenized pump laser is incident through the light inlet 12, it is reflected by the parabolic reflector 3, the laser head 2, the parabolic reflector 3, and the first reflector D1 in sequence before arriving at the first reflector C1, completing the first-pass absorption of the pump laser by the laser head 2; after the first reflector C1 reflects the received pump laser, it is reflected by the parabolic reflector 3, the laser head 2, the parabolic reflector 3, and the first reflector D2 in sequence before arriving at the first reflector C2, completing the second-pass absorption of the pump laser by the laser head 2; after the first reflector C2 reflects the received pump laser, it is reflected by the parabolic reflector 3, the laser head 2, the parabolic reflector 3, and the first reflector D3 in sequence before arriving at the first reflector C4, completing the second-pass absorption of the pump laser by the laser head 2 Mirror C3 completes the third-pass absorption of the pump laser by the laser head 2; the first reflector C3 reflects the received pump laser, which is reflected by the parabolic reflector 3, laser head 2, parabolic reflector 3, and the first reflector D4 in sequence before arriving at the first reflector C4, completing the fourth-pass absorption of the pump laser by the laser head 2; the first reflector C4 reflects the received pump laser, which is reflected by the parabolic reflector 3, laser head 2, parabolic reflector 3, and the first reflector D5 in sequence before arriving at the first reflector C5, completing the fifth-pass absorption of the pump laser by the laser head 2; the first reflector C5 reflects the received pump laser, which is reflected by the parabolic reflector 3, laser head 2, parabolic reflector 3, and the first reflector D5 in sequence before arriving at the first reflector C5, completing the fifth-pass absorption of the pump laser by the laser head 2 After being reflected by the parabolic reflector 3 and the first reflector D6, the laser beam reaches the first reflector C6, completing the sixth absorption of the pump laser by the laser head 2; the first reflector C6 reflects the received pump laser, and then it is reflected by the parabolic reflector 3, the laser head 2, the parabolic reflector 3, and the second reflector F1, and then reaches the second reflector E1, completing the seventh absorption of the pump laser by the laser head 2; the second reflector E1 reflects the received pump laser, and then it is reflected by the parabolic reflector 3, the laser head 2, the parabolic reflector 3, and the second reflector F2, and then reaches the second reflector E2, completing the eighth absorption of the pump laser by the laser head 2; the second reflector E2 reflects the received pump laser. After the pump laser is reflected, it is reflected by the parabolic reflector 3, the laser head 2, the parabolic reflector 3, and the second reflector F3 in sequence before arriving at the second reflector E3, completing the ninth pass absorption of the pump laser by the laser head 2; after the second reflector E3 reflects the received pump laser, it is reflected by the parabolic reflector 3, the laser head 2, the parabolic reflector 3, and the second reflector F4 in sequence before arriving at the second reflector E4, completing the tenth pass absorption of the pump laser by the laser head 2; after the second reflector E4 reflects the received pump laser, it is reflected by the parabolic reflector 3, the laser head 2, and the parabolic reflector 3 in sequence before arriving at the light outlet 13, completing the eleventh pass absorption of the pump laser by the laser head 2. Through the double-layer multi-pass pump optical system of the present invention, the laser head 2 can effectively absorb more passes of the pump laser and provide energy storage for it more efficiently.

[0069] In this embodiment, the light inlet 12 and the light outlet 13 can also be used interchangeably, in which case the transmission path of the pump laser is reversed. The number of reflectors can be increased or decreased by multiples of 2, which will increase or decrease the number of absorption paths of the pump laser by the laser head 2 accordingly.

[0070] Example 4

[0071] The fourth embodiment has the same structure as the third embodiment, and the only difference is that a zero-degree reflector is provided on the light outlet 13 of the second embodiment, and the transmission distance of the pump laser from the parabolic reflector 3 to the zero-degree reflector is equal to the focal length of the parabolic reflector 3, which is used to make the pump laser return along the original transmission path after being reflected by the zero-degree reflector, thereby doubling the number of times the laser head 2 absorbs the pump laser.

[0072] The above description is only used to illustrate the technical solution of the present invention, rather than to limit it. For ordinary professional and technical personnel in this field, the specific technical solutions recorded in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents. These modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution protected by the present invention.

Claims

1. A single-layer multi-pass pumping optical system, characterized in that: It comprises 2n reflecting mirrors, a laser head (2) coaxially arranged in sequence, a reflecting mirror mounting frame (1) and a parabolic reflecting mirror (3), where n≥2; The reflector mounting frame (1) is axially provided with a light hole (11), a light inlet (12), and a light outlet (13); the light hole (11) is located at the center of the reflector mounting frame (1); 2n reflectors are arranged on an end surface of a reflector mounting frame (1) close to a parabolic reflector (3), and the reflective surfaces of the reflectors are arranged at an angle relative to the reflector mounting frame (1); the 2n reflectors are evenly divided into two groups, and the n reflectors of the first group, the n reflectors of the second group, the light outlet (13), and the light inlet (12) are evenly distributed along the same circumference in sequence; The reflection surfaces of the i-th reflector in the first group and the i-th reflector in the second group have the same inclination angle, and the reflection surfaces of the two are arranged opposite to each other, i = 1, 2, ..., n; The reflecting surface of the laser head (2) is located at the focal position of the parabolic reflector (3); The light inlet (12) is located on the incident light path of the pump laser. The incident light of the pump laser enters the parabolic reflector (3) through the light inlet (12), and then travels back and forth n times through the parabolic reflector (3), the laser head (2), the parabolic reflector (3), the i-th reflector of the second group, the i-th reflector of the first group, and the parabolic reflector (3). After being reflected by the laser head (2) and the parabolic reflector (3), the light is emitted through the light outlet (13); wherein the value of i starts from 1 and increases by 1 each time it travels back and forth. The sum of the transmission distances of the pump laser from the parabolic reflector (3) to the i-th reflector in the second group, the i-th reflector in the second group to the i-th reflector in the first group, and the i-th reflector in the first group to the parabolic reflector (3) is equal to twice the focal length of the parabolic reflector (3).

2. The single-layer multi-pass pumping optical system according to claim 1, characterized in that: The light outlet (13) is provided with a zero-degree reflector for allowing the pump laser to be reflected by the zero-degree reflector and then returned along the original transmission path; The transmission distance of the pump laser from the parabolic reflector (3) to the zero-degree reflector is equal to the focal length of the parabolic reflector (3).

3. The single-layer multi-pass pumping optical system according to claim 1 or 2, characterized in that: The laser head (2) is a transmission laser head or a reflection laser head.

4. The single-layer multi-pass pumping optical system according to claim 3, characterized in that: The inclination angles of the reflecting surfaces of the 2n reflecting mirrors are all 45°.

5. The single-layer multi-pass pumping optical system according to claim 4, characterized in that: Said n=4.

6. A double-layer multi-pass pumping optical system, characterized in that: It comprises 2p first reflecting mirrors, 2q second reflecting mirrors, a laser head (2) coaxially arranged in sequence, a reflecting mirror mounting frame (1) and a parabolic reflecting mirror (3), where p≥2, q≥2, and p≥q; The reflector mounting frame (1) is axially provided with a light hole (11), a light inlet (12), and a light outlet (13); the light hole (11) is located at the center of the reflector mounting frame (1); The 2p first reflectors and the 2q second reflectors are all arranged on an end surface of a reflector mounting frame (1) close to a parabolic reflector (3), and the reflecting surfaces of the first reflectors and the second reflectors are both arranged tilted relative to the reflector mounting frame (1); the lowest point of the reflecting surface of the first reflector is higher than the highest point of the reflecting surface of the second reflector; 2p first reflectors and 2q second reflectors are respectively divided into two groups, wherein the p first reflectors of the first group, the p first reflectors of the second group, a light inlet (12), and a second reflector of the first group are uniformly distributed along the same circumference in sequence to form a first ring position; q-1 second reflectors of the first group, the q second reflectors of the second group, and a light outlet (13) are uniformly distributed along the same circumference in sequence in the opposite direction to form a second ring position; the second ring position is located in the inner circle of the first ring position, and the light inlet (12) and the light outlet (13) are located at the same radial position of the first ring position and the second ring position; The reflection surfaces of the j-th first reflector in the first group and the j-th first reflector in the second group have the same inclination angle, and the two reflection surfaces are arranged opposite to each other, j = 1, 2, ..., p; the reflection surfaces of the k-th second reflector in the first group and the k-th second reflector in the second group have the same inclination angle, and the two reflection surfaces are arranged opposite to each other, k = 1, 2, ..., q; The reflecting surface of the laser head (2) is located at the focal position of the parabolic reflector (3); The light inlet (12) is located on the incident light path of the pump laser. The incident light of the pump laser is incident on the parabolic reflector (3) through the light inlet (12). The pump laser passes through the parabolic reflector (3), the laser head (2), the parabolic reflector (3), the j-th first reflector of the second group, the j-th first reflector of the first group, and the parabolic reflector (3) for p round trips, and then passes through the parabolic reflector (3), the laser head (2), the parabolic reflector (3), the k-th second reflector of the first group, the k-th second reflector of the second group, and the parabolic reflector (3) for q round trips, and then passes through the laser head (2) and the parabolic reflector (3) before being emitted through the light outlet (13); wherein the value of j starts from 1 and increases by 1 every round trip; the value of k starts from 1 and increases by 1 every round trip; The sum of the transmission distances of the pump laser from the parabolic reflector (3) to the jth first reflector of the second group, the jth first reflector of the second group to the jth first reflector of the first group, and the jth first reflector of the first group to the parabolic reflector (3) is equal to twice the focal length of the parabolic reflector (3); The sum of the transmission distances of the pump laser from the parabolic reflector (3) to the kth second reflector in the second group, the kth second reflector in the second group to the kth second reflector in the first group, and the kth second reflector in the first group to the parabolic reflector (3) is equal to twice the focal length of the parabolic reflector (3).

7. The double-layer multi-pass pumping optical system according to claim 6, characterized in that: The light outlet (13) is provided with a zero-degree reflector for allowing the pump laser to be reflected by the zero-degree reflector and then returned along the original transmission path; The transmission distance of the pump laser from the parabolic reflector (3) to the zero-degree reflector is equal to the focal length of the parabolic reflector (3).

8. The double-layer multi-pass pumping optical system according to claim 6 or 7, characterized in that: The laser head (2) is a transmission laser head or a reflection laser head.

9. The double-layer multi-pass pumping optical system according to claim 8, characterized in that: The inclination angle of the reflecting surfaces of the 2p first reflecting mirrors is 45°; The inclination angle of the reflecting surfaces of the 2q second reflecting mirrors is 45°.

10. The double-layer multi-pass pumping optical system according to claim 9, characterized in that: Said p=6, q=4.

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