A time sequential laser

Abstract

The application relates to a gain medium alternating emission laser, which belongs to the laser field and comprises a pumping source, a multi-unit gain medium module, an excitation light module, a light beam scanning module and an electronic control unit. The pumping source inputs pumping light to the multi-unit gain medium module and activates the multi-unit gain medium module. The light beam scanning module acts on the excitation light module or the multi-unit gain medium module, so that excitation light generated by the excitation light module periodically scans the multi-unit gain medium module. The multi-unit gain medium module is divided into partitions according to regions occupied by the residence period of the excitation light. The electronic control unit is used for sending synchronous control signals to the multi-unit gain medium module and the light beam scanning module, so that each partition of the multi-unit gain medium module is excited and emits to form laser light in turn. The application has the effects of high-power output, high light beam quality, low manufacturing cost and high reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser, in particular to a time sequence emitting laser. BACKGROUND

[0002] Laser has been widely used in material processing, military, communication, sensing, medicine and illumination, etc. fields, and has formed a huge industry so far. Laser is the core component of laser industry. The performance of laser, especially laser power and beam quality, has a decisive influence on the sustainable development of laser industry. At present, the common working modes of laser are pulse mode and continuous laser mode. Under the same output power, the peak power of laser output in pulse mode is much higher than that in continuous laser mode. By time sequence beam combining of multiple low-frequency pulse lasers with the same parameters and non-overlapping in time domain, the repetition frequency can be improved under the condition of keeping the single pulse energy unchanged, so as to improve the average power and brightness.

[0003] At present, there are many patents related to time sequence beam combining, such as patent application No. CN109619A, which is a laser time sequence beam combining device based on diffraction grating. The time sequence beam combining method disclosed in the patent combines multiple spectral synthesis beams in time sequence, and then combines them again in time sequence through grating switching. The multi-cavity synthesis beam formed by this method has very high average power.

[0004] In the process of implementing the present application, the inventors found that the above-mentioned technology at least has the following problems: all traditional time sequence beam combining systems need to select multiple lasers with the same parameters for beam combining, which involves more precise optical elements and precise optical processing technology, and the manufacturing cost is high, and the reliability is poor. SUMMARY

[0005] In order to overcome the above-mentioned shortcomings of traditional time sequence beam combining laser system, the present application provides a time sequence emitting laser.

[0006] The time sequence emitting laser provided by the present application adopts the following technical scheme:

[0007] The timing laser emitter comprises a pump source, a multi-unit gain medium module, an excitation light module, a beam scanning module and an electronic control unit, the pump source inputs pump light to the multi-unit gain medium module and activates the multi-unit gain medium module, the beam scanning module acts on the excitation light module or the multi-unit gain medium module, so that the excitation light generated by the excitation light module periodically scans the multi-unit gain medium module, the multi-unit gain medium module is divided into multiple sub-zones according to the area occupied by the excitation light staying period, and the electronic control unit is used for sending a synchronous control signal to the multi-unit gain medium module and the beam scanning module respectively, so that each sub-zone of the multi-unit gain medium module is sequentially excited to emit laser.

[0008] By using the above technical scheme, when in use, the pump source continuously inputs pump light to the multi-unit gain medium module, so that the multi-unit gain medium module is activated and generates spontaneous emission, the beam scanning module acts on the excitation light module or the multi-unit gain medium module, so that the excitation light generated by the excitation light module periodically scans the multi-unit gain medium module, the multi-unit gain medium module is divided into multiple sub-zones according to the area occupied by the excitation light staying period, and each sub-zone is directly acted on by the excitation light module, so that a laser pulse is formed, and all the laser pulses generated by the sub-zones are finally combined to form a continuous single-cavity giant pulse laser output. Since many complex parts and optical calibration are not required to achieve the same effect of the timing beam combination multi-cavity laser emission system, the shortcomings of high cost and poor reliability of the traditional timing beam combination multi-cavity laser system can be overcome.

[0009] Optionally, the excitation light module comprises a high-reflection unit and a low-reflection unit constituting a resonant cavity, at least a part of an optical channel of the resonant cavity is a free-space optical channel, the multi-unit gain medium module is located in the optical channel of the resonant cavity, and each sub-zone of the multi-unit gain medium module is sequentially scanned by excitation light in the optical channel and excited to emit a laser pulse.

[0010] Optionally, a Q switch is arranged in the optical channel of the resonant cavity, the Q switch is located between the multi-unit gain medium module and the low-reflection unit, and the resonant cavity is switched between a low-loss open state and a high-loss closed state based on the control of the electronic control unit.

[0011] Optionally, the high-reflection unit is a free-space high-reflection mirror or a fiber grating, and is arranged in a separate distance from the multi-unit gain medium module.

[0012] Optionally, the high-reflection unit is a high-reflection film with a reflectivity higher than 98%, and the high-reflection unit is coated on the surface of the multi-unit gain medium module.

[0013] By adopting the technical scheme, the high-reflection unit is directly attached to the multi-unit gain medium module, so that the number of solid interfaces in the light path is reduced, and the loss of the resonant cavity is reduced.

[0014] Optionally, the excitation light module comprises a seed light source and a fiber collimator, the seed light source is configured with an optical isolator, an optical channel is formed between the seed light source and the fiber collimator, the multi-unit gain medium module is located at the optical channel part, and each sub-area of the multi-unit gain medium module enters the optical channel in turn, so that the seed laser emitted by the seed light source is power amplified to form a laser pulse.

[0015] Optionally, the beam scanning module comprises a mechanical driver connected to the multi-unit gain medium module and used to drive the multi-unit gain medium module to periodically displace in a direction perpendicular to the optical channel.

[0016] Optionally, the beam scanning module comprises an electronic driving circuit and a pair of N-select-one beam scanning switches, each of the beam scanning switches comprises a main channel and N branch channels, the main channel and each branch channel of the same beam scanning switch are periodically connected in turn, the main channel is connected to the optical channel, the branch channels of the two beam scanning switches are arranged in one-to-one correspondence, the two corresponding branch channels are connected to each other and form a common branch channel, the multi-unit gain medium module is located in the common branch channel between the two beam scanning switches, and the electronic driving circuit controls each common branch channel to be connected to the optical channel in turn based on the control of the electronic control unit, so that the seed laser in the optical channel periodically scans the multi-unit gain medium module.

[0017] In summary, the present application has at least one of the following beneficial technical effects:

[0018] 1. During use, the pump source continuously inputs pump light to the multi-unit gain medium module, so that the multi-unit gain medium module is activated and generates spontaneous radiation, the beam scanning module acts on the excitation light module or the multi-unit gain medium module, so that the excitation light generated by the excitation light module periodically scans the multi-unit gain medium module, the multi-unit gain medium module is divided into multiple sub-areas according to the area occupied by the excitation light, and each sub-area is directly acted on by the excitation light module to form a laser pulse. All laser pulses generated by the sub-areas are finally combined to form a continuous single-cavity giant pulse laser output. Since a large number of complex parts and optical calibration are not required to achieve the same effect as the time sequence beam combination multi-cavity laser emission system, the cost of the traditional time sequence beam combination multi-cavity laser system can be reduced, and the reliability can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1is a schematic diagram for embodying the working principle of the time-sequential laser in Embodiment 1 of the present application;

[0020] Figure 2 is a schematic diagram for embodying the working principle of the time-sequential laser in Embodiment 2 of the present application;

[0021] Figure 3 is a schematic diagram for embodying the working principle of the time-sequential laser in Embodiment 3 of the present application;

[0022] Figure 4 is a schematic diagram for embodying the working principle of the time-sequential laser in Embodiment 4 of the present application.

[0023] BRIEF DESCRIPTION OF DRAWINGS Referring to the drawings: 1, multi-unit gain medium module; 2, pump light source; 31, high reflection unit; 32, low reflection unit; 33, seed light source; 34, fiber collimator; 41, mechanical driver; 42, electronic driving circuit; 43, beam scanning switch; 5, electronic control unit; 6, output port; 7, Q switch. DETAILED DESCRIPTION

[0024] The following will be described in detail in combination with the accompanying drawings Figures 1-4 The present application will be further described in detail.

[0025] The embodiment of the present application discloses a time-sequential laser. The time-sequential laser adopted by the present application is a laser that makes the sub-regions of a gain medium emit laser alternately by scanning the gain medium with excitation light. The excitation light can be generated by spontaneous emission of the gain medium in the resonant cavity of the laser through mode competition, or can be generated by an independent seed laser. The former forms a Q-switched laser, and the latter forms a MOPA type laser.

[0026] Embodiment 1:

[0027] Referring to Figure 1 The time-sequential laser disclosed in the embodiment comprises a multi-unit gain medium module 1, a pump light source 2, an excitation light module, a beam scanning module, an electronic control unit 5 and an output port 6, and the time-sequential laser disclosed in the embodiment is a Q-switched laser. The pump light emitted by the pump light source 2 is coupled into and activates the multi-unit gain medium module 1, so that the multi-unit gain medium module 1 enters an activated state to generate spontaneous emission.

[0028] Referring to Figure 1In the embodiment, the excitation light module comprises a high-reflection unit 31 and a low-reflection unit 32, the high-reflection unit 31 and the low-reflection unit 32 constitute a resonant cavity and form an optical channel B (indicated by a thick dashed line in the figure), and the multi-cell gain medium module 1 is partially located in the resonant cavity. The resonant cavity is provided with a Q-switch 7, the Q-switch 7 is arranged between the multi-cell gain medium module 1 and the low-reflection unit 32, and the Q-switch 7 is used to control the loss of the resonant cavity, so that the resonant cavity is periodically switched between a low-loss on state and a high-loss off state. The light transmission cross section of the multi-cell gain medium module 1 is larger than the cross section of the optical channel B of the resonant cavity, and the multi-cell gain medium module 1 can be a large-size rare earth doped material sheet or a disc-shaped unit.

[0029] With reference to Figure 1 The part of the multi-cell gain medium module 1 located in the optical channel B is subjected to oscillation amplification of the spontaneous radiation to form laser pulses. The beam scanning module comprises a mechanical driver 41 directly connected to the multi-cell gain medium module 1 and used to drive the multi-cell gain medium module 1 to periodically move in a direction perpendicular to the optical channel B.

[0030] With reference to Figure 1 The electronic control unit 5 is signal-connected to the mechanical driver 41 and the Q-switch 7 respectively, and is used to send synchronous control signals to the mechanical driver 41 and the Q-switch 7 respectively, so that the state switching of the resonant cavity and the stepping time of the mechanical driver 41 are synchronized. The multi-cell gain medium module 1 is divided into multiple sub-zones according to the size of the position occupied by the optical channel B. In use, the electronic control unit 5 controls the mechanical driver 41 to operate, and under the driving of the mechanical driver 41, the sub-zones of the multi-cell gain medium module 1 enter the optical channel B in turn and are quickly moved out after a short stay. During the stay, the resonant cavity is in a low-loss on state, so that the sub-zones can be scanned, and the spontaneous radiation of the sub-zones is subjected to resonant amplification to form laser pulses. The laser pulses formed by the sub-zones are combined to form a continuous laser output that can be output through the output port 6.

[0031] It should be noted that the high-reflection unit 31, the low-reflection unit 32 and the pump light source 2 in the above description can be selected from two configurations of free-space coupling and fiber coupling. When free-space coupling is adopted, the high-reflection unit 31 can adopt an independent high-reflection mirror and be arranged separately from the multi-cell gain medium module 1; or the high-reflection unit 31 can be selected as a high-reflection film with a reflectivity higher than 98% and be directly coated on the surface of the multi-cell gain medium module 1, so as to reduce the number of solid interfaces in the optical path and reduce the loss of the resonant cavity. When fiber coupling is adopted, the high-reflection unit 31 and the low-reflection unit 32 can be selected as fiber gratings, and a fiber collimator 34 is used to form a free-space optical channel in a resonant cavity formed by optical fibers, so as to form relative movement between the multi-cell gain medium module 1 and the optical channel B in the resonant cavity.

[0032] The implementation principle of the embodiment 1 of the present application is as follows: in use, the pump light source 2 inputs pump light to the multi-cell gain medium module 1, so that the multi-cell gain medium module 1 enters an active state and generates spontaneous radiation, at the same time, the electronic control unit 5 sends a synchronous control signal to the Q-switched laser and the mechanical driver 41 respectively, so that the mechanical driver 41 drives each sub-zone of the multi-cell gain medium module 1 to enter the light passage B in turn and stay for a short time, the Q-switched laser controls the resonant cavity to enter a low-loss open state during the stay of the multi-cell gain medium module 1, so that part of the spontaneous radiation emitted by the sub-zone of the multi-cell gain medium module 1 staying in the light passage B is amplified to form a laser pulse, all the laser pulses are combined to form a continuous pulse laser, and finally output through the output port 6.

[0033] In other optional embodiments based on the embodiment 1, the above-mentioned Q-switch 7 can also be omitted, so as to improve the electro-optical conversion efficiency and simplify the structure.

[0034] Embodiment 2:

[0035] With reference to Figure 2 , the difference between the embodiment 2 and the embodiment 1 is that the light beam scanning module comprises an electronic driving circuit 42 and a pair of N-of-1 light beam scanning switches 43 arranged between the high-reflection unit 31 and the low-reflection unit 32, wherein N is a natural number greater than 1. Each light beam scanning switch 43 comprises a main passage and N branch passages, the main passage of each light beam scanning switch 43 is connected with the light passage B, and the N branch passages of the two light beam scanning switches 43 are connected one by one to form N common branch passages Bn (n=1, 2, 3…N). The electronic driving circuit 42 is used to control the synchronous switching of the two light beam scanning switches 43, so that the main passage of each light beam scanning switch 43 is connected with each common branch passage Bn in turn through the respective branch passage. The sub-zone of the multi-cell gain medium module 1 located in the common branch passage Bn in the connected state is excited and generates pulse laser to the light passage B. The electronic control unit 5 is signal connected to the electronic driving circuit 42 and the Q-switch 7 respectively, and is used to send a synchronous control instruction to the two respectively, so that the resonant cavity is also in a low-loss open state during the connection of each common branch passage Bn. With the laser emission of each sub-zone of the multi-cell gain medium module 1 in turn, the laser output is finally formed at the output port 6. The N-of-1 light beam scanning switch 43 can be a light beam scanning switch (also commonly referred to as a light beam deflector or a light beam switcher) based on a scanning galvanometer, an electro-optical scanner, an acousto-optical scanner, a magneto-optical scanner, a liquid crystal scanner, or a MEMS scanning mirror, the repetition frequency selection range is wider, and the better effect can be obtained based on the optimization of different application requirements.

[0036] Embodiment 3:

[0037] With reference toFigure 3 The timing laser disclosed in the embodiment is a MOPA laser, comprising a multi-cell gain medium module 1, a pump light source 2, an excitation light module, a beam scanning module, an electronic control unit 5 and an output port 6. The pump light emitted by the pump light source 2 is coupled into the multi-cell gain medium module 1 and activates the multi-cell gain medium module 1 to generate spontaneous radiation. The excitation light module comprises a seed light source 33 and a fiber collimator 34. The seed light source 33 is configured with an optical isolator (not shown in the figure), and a free space optical channel C is formed between the seed light source 33 and the fiber collimator 34. The multi-cell gain medium module 1 is located between the seed light source 33 and the fiber collimator 34, and can be a single cell of a rod, a slab or a fiber coil with a light section equal to the section of the optical channel C, or a multi-cell array with a light section equal to the section of the optical channel C, of which the multi-cell array is the most preferable.

[0038] With reference to Figure 3 The beam scanning module comprises a mechanical driver 41 connected to the multi-cell gain medium module 1 for driving the multi-cell gain medium module 1 to make periodic motion in a direction perpendicular to the optical channel C. The electronic control unit 5 is signal connected to the mechanical driver 41 and the seed light source 33 respectively, for issuing synchronization control instructions to the mechanical driver 41 and the seed light source 33 respectively, so that the mechanical driver 41 controls each sub-zone of the multi-cell gain medium module 1 to enter the optical channel C in turn and stay for a short time, while the seed light source 33 emits a laser pulse during the stay of the multi-cell gain medium module 1, and the laser pulse is amplified in power by the sub-zone of the multi-cell gain medium module 1 staying in the optical channel C. The periodic laser pulses are collimated by the fiber collimator 34 in turn, and finally output through the output port 6 to form high-power pulsed laser.

[0039] Embodiment 4:

[0040] With reference to Figure 4The embodiment is different from the embodiment 3 in that the light beam scanning module comprises an electronic driving circuit 42 and a pair of N-of-1 light beam scanning switches 43 arranged between the seed light source 33 and the fiber collimator 34, wherein N is a natural number greater than 1. The multi-unit gain medium module 1 is located between the two light beam scanning switches 43. Each light beam scanning switch 43 comprises one main channel and N branch channels, the main channels of the light beam scanning switches 43 are all connected with the light channel C, and the N branch channels of the two light beam scanning switches 43 are connected one by one to form N common branch channels Cn (n = 1, 2, 3…N). The electronic control unit 5 is used to send a synchronization control signal to the electronic driver and the seed light source 33 respectively, so that the electronic driver controls the pair of light beam scanning switches 43 to periodically switch the common branch channel Cn and make a short pause after each switching, and at the same time, the seed light source 33 emits a laser pulse during the short pause of each common branch channel Cn. The selectable range of the light beam scanning switch 43 is wide, which can be a light beam scanning switch (also called a light beam deflector or a light beam switcher) based on a scanning galvanometer, an electro-optical scanner, an acousto-optical scanner, a magneto-optical scanner, a liquid crystal scanner or a MEMS scanning mirror, and the electro-optical scanning switch is the most selectable.

[0041] Compared with the technical scheme of the Q-switched laser adopted in the embodiments 1 and 2, the MOPA laser adopted in the embodiments 3 and 4 has higher average power and brightness.

[0042] In any of the above embodiments, for any one partition of the multi-unit gain medium module 1, the partition is not connected with the light channel B or the light channel C for most of the time in a period, and the multi-unit gain medium module 1 still continuously receives pump light, during which a large number of light-emitting particles accumulate, and when the partition of the multi-unit gain medium module 1 is connected with the light channel B or C, a giant pulse of stimulated emission laser is emitted, each partition emits alternately, by prolonging the light-emitting particle accumulation time and increasing the number of light-emitting particle accumulation, the giant pulse energy, the peak power and the average power can be improved, and high beam quality can be maintained.

[0043] The above embodiments are only used to illustrate the technical scheme of the present application, and do not limit the protection scope of the application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on these embodiments, all other embodiments obtained by a person of ordinary skill in the art without creative labor belong to the scope to be protected by the present application.

Claims

1. A time sequential emitting laser, said time sequential emitting laser being a Q-switched laser, characterized in that, The Q-switched laser comprises a multi-cell gain medium module (1), a pump light source (2), an excitation light module (3), a beam scanning module (4), an electronic control unit (5) and an output port (6), the pump light emitted by the pump light source (2) is coupled into and activates the multi-cell gain medium module (1), so that the multi-cell gain medium module (1) enters an activated state to generate spontaneous radiation, the beam scanning module (4) acts on the excitation light module (3) or the multi-cell gain medium module (1), so that the excitation light generated by the excitation light module (3) periodically scans the multi-cell gain medium module (1), the multi-cell gain medium module (1) is partitioned according to the area occupied by the residence period of the excitation light, and the electronic control unit (5) is configured to send synchronous control signals to the multi-cell gain medium module (1) and the beam scanning module (4) respectively, so that each partition of the multi-cell gain medium module (1) is excited to emit laser in turn. The excitation light module (3) comprises a high-reflection unit (31) and a low-reflection unit (32) forming a resonant cavity, at least a part of an optical channel of the resonant cavity is a free-space optical channel, the multi-cell gain medium module (1) is located in the optical channel of the resonant cavity, each partition of the multi-cell gain medium module (1) is scanned by the optical channel in turn and excited to emit laser pulses, and a Q-switch (7) is arranged in the optical channel of the resonant cavity, the Q-switch (7) is located between the multi-cell gain medium module (1) and the low-reflection unit (32) and is configured to control the resonant cavity to switch between a low-loss on state and a high-loss off state based on the control of the electronic control unit (5). The high-reflection unit (31) is a free-space high-reflection mirror or a fiber grating and is arranged at a discrete distance from the multi-cell gain medium module (1), or the high-reflection unit (31) is a high-reflection film with a reflectivity higher than 98% and is coated on the surface of the multi-cell gain medium module (1).

2. A time sequential emitting laser, the time sequential emitting laser being a MOPA laser, characterized in that, The MOPA laser comprises a multi-cell gain medium module (1), a pump light source (2), an excitation light module (3), a beam scanning module (4), an electronic control unit (5) and an output port (6), the pump light emitted by the pump light source (2) is coupled into the multi-cell gain medium module (1) and activates the multi-cell gain medium module (1), so that the multi-cell gain medium module (1) generates spontaneous radiation, the beam scanning module (4) acts on the excitation light module (3) or the multi-cell gain medium module (1), so that the excitation light generated by the excitation light module (3) periodically scans the multi-cell gain medium module (1), the multi-cell gain medium module (1) is partitioned according to the area occupied by the residence period of the excitation light, and the electronic control unit (5) is configured to send synchronous control signals to the multi-cell gain medium module (1) and the beam scanning module (4) respectively, so that each partition of the multi-cell gain medium module (1) is excited to emit laser in turn. The excitation light module (3) comprises a seed light source (33) and a fiber collimator (34), the seed light source (33) is configured with an optical isolator, an optical channel is formed between the seed light source (33) and the fiber collimator (34), the multi-unit gain medium module (1) is located at the part of the optical channel, and each sub-area of the multi-unit gain medium module (1) enters the optical channel in turn, thereby amplifying the seed laser emitted by the seed light source (33) to form a laser pulse. The multi-unit gain medium module (1) is a unit of a rod, a strip or a fiber coil with an optical section equal to the section of the optical channel, or the multi-unit gain medium module (1) is a multi-unit array of a rod, a strip or a fiber coil with an optical section equal to the section of the optical channel.

3. The time sequential laser of any of claims 1-2, wherein, The beam scanning module (4) comprises a mechanical driver (41) connected to the multi-unit gain medium module (1) for driving the multi-unit gain medium module (1) to periodically displace in a direction perpendicular to the optical channel.

4. The time sequential laser of any of claims 1-2, wherein, The beam scanning module (4) comprises an electronic driving circuit (42) and a pair of N-select-one beam scanning switches (43), each of the beam scanning switches (43) comprises a main channel and N branch channels, the main channel and each branch channel of the same beam scanning switch (43) are periodically connected in turn, the main channel is connected to the optical channel, the branch channels of the two beam scanning switches (43) are arranged one by one, and the corresponding two branch channels are connected to each other and form a common branch channel, the multi-unit gain medium module (1) is located at the part of the common branch channel between the two beam scanning switches (43), and the electronic driving circuit (42) controls each common branch channel to be connected to the optical channel in turn based on the control of the electronic control unit (5), so that the seed laser in the optical channel periodically scans the multi-unit gain medium module (1).

Images