A pulse laser adjustment system

Abstract

The present invention is applicable to the field of pulsed laser technology and provides a pulsed laser modulation system. The system includes: a laser seed source for emitting a laser signal; a polarization-maintaining circulator having an incident end, a first emission end, and a second emission end, with the laser seed source and the incident end of the polarization-maintaining circulator being located on the same optical path; a fiber preamplifier and a laser pulse stretcher, with the first emission end, the fiber preamplifier, and the laser pulse stretcher being sequentially arranged on the same optical path; and an acousto-optic modulator and a fiber amplifier, with the second emission end, the acousto-optic modulator, and the fiber amplifier being sequentially arranged on the same optical path. The present invention proposes a design scheme for a pulsed laser modulation device that integrates stretching, preamplification, and frequency selection. By using this scheme, a low-repetition-rate pulsed laser output with a compact structure, good stability, and a high signal-to-noise ratio can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of pulse laser technology, and in particular relates to a pulse laser adjustment system. Background Art

[0002] Lasers with pulse widths less than 15 ps, maximum single-pulse energy less than 30 mJ, and repetition rates above 1 kHz are called ultrafast lasers. Ultrafast lasers are important tools for precision machining, primarily utilizing field effects to achieve material processing. This processing method not only achieves higher precision but also minimizes surface damage, a process known as "cold processing." Because the pulse width of ultrafast laser seed sources is typically less than 15 ps, and the repetition rate is typically between 20 and 50 MHz, directly amplifying these high-repetition-rate lasers, even with pulse widths in the femtosecond range, remains unsuitable for precision machining. This high repetition rate of the laser pulses still results in heat accumulation, significantly reducing machining effectiveness. Generally, ultrafast lasers used in precision machining have two key characteristics: a low repetition rate (typically below kilohertz), ensuring that the maximum energy is concentrated into a single pulse during amplification; and a narrow pulse width (typically below femtoseconds). In order to obtain low-repetition-rate laser pulses, the pulse repetition frequency of the ultrafast laser seed source needs to be reduced to below kilohertz. In order to ensure that the pulsed laser is not distorted during the amplification process and does not damage the devices in the laser amplifier, the laser pulse needs to be broadened.

[0003] Currently, ultrafast laser systems used in precision machining typically feature high peak power, narrow pulse width, and high beam quality. These systems typically consist of five components arranged in sequence: a seed source, a pulse stretcher, an acousto-optic modulator, a pulse power amplifier, and a pulse compression module.

[0004] However, if the seed source's pulsed laser is directly fed into a pulse stretcher to achieve the pulse stretching effect, the output power of the stretched laser pulse will be significantly reduced due to the relatively low reflectivity of the pulse stretcher. Furthermore, if the stretched laser pulse is directly fed into an acousto-optic modulator for frequency reduction, the final output power will be greatly reduced, especially when the laser pulse repetition frequency is reduced to the kHz level, where the output power will drop dramatically. Furthermore, if the frequency-reduced pulsed laser is directly fed into a pulse power amplifier module for amplification, the power amplification effect will be greatly affected due to the low signal light power. Summary of the Invention

[0005] An embodiment of the present invention provides a pulse laser adjustment system, aiming to solve at least one technical problem in the prior art.

[0006] The embodiment of the present invention is implemented as follows: a pulse laser modulation system, the system comprising:

[0007] A laser seed source, used for emitting laser signals;

[0008] A polarization-maintaining circulator having an incident end, a first emitting end, and a second emitting end, wherein the laser seed source and the incident end of the polarization-maintaining circulator are on the same optical path;

[0009] An optical fiber pre-amplifier and a laser pulse stretcher, wherein the first emission end, the optical fiber pre-amplifier and the laser pulse stretcher are sequentially arranged on the same optical path;

[0010] The acousto-optic modulator and the optical fiber amplifier, the second emission end, the acousto-optic modulator and the optical fiber amplifier are sequentially arranged on the same optical path.

[0011] Preferably, the optical fiber preamplifier comprises a first pump source, a first polarization-maintaining wavelength division multiplexer, and a first polarization-maintaining active optical fiber;

[0012] Wherein, the first emission end, the first polarization-maintaining wavelength division multiplexer, the first polarization-maintaining active optical fiber, and the laser pulse stretcher are sequentially arranged on the same optical path;

[0013] The emission signal of the first pump source and the laser signal emitted from the first emission end are combined into one laser signal through the first polarization-maintaining wavelength division multiplexer and then emitted into the first polarization-maintaining active optical fiber.

[0014] Preferably, the optical fiber amplifier includes a second pump source, a second polarization-maintaining wavelength division multiplexer, and a second polarization-maintaining active optical fiber;

[0015] The second emission end, the acousto-optic modulator, the second polarization-maintaining wavelength division multiplexer, and the second polarization-maintaining active optical fiber are sequentially arranged on the same optical path;

[0016] The emission signal of the second pump source and the laser signal emitted from the acousto-optic modulator are combined into one laser signal through the second polarization-maintaining wavelength division multiplexer and then emitted into the second polarization-maintaining active optical fiber.

[0017] Preferably, the optical fiber amplifier further comprises a polarization-maintaining filter, and the optical fiber amplifier and the polarization-maintaining filter are sequentially arranged on the same optical path;

[0018] The polarization-maintaining filter is used to filter out the fluorescence signal in the laser signal emitted by the optical fiber amplifier.

[0019] Preferably, the optical fiber amplifier further comprises a polarization-maintaining isolator, and the polarization-maintaining filter and the polarization-maintaining filter are sequentially arranged on the same optical path;

[0020] The laser signal after the fluorescence is filtered out by the polarization-maintaining filter is emitted through the polarization-maintaining isolator.

[0021] Preferably, the pulse laser adjustment system further includes:

[0022] A pulse frequency selection module is used to select the frequency of the radio frequency signal according to the laser seed source and the acousto-optic modulator.

[0023] Preferably, the laser seed source is an ultrafast laser seed source.

[0024] The beneficial effects achieved by the present invention are as follows: by providing a polarization-maintaining circulator and an optical fiber pre-amplifier, the laser is pre-amplified and then input into the laser pulse stretcher, thereby improving the output power of the pulsed laser after entering the laser pulse stretcher for pulse stretching; due to the reflection effect of the laser pulse stretcher, the laser after stretching will enter the optical fiber pre-amplifier again, and then the laser will be amplified for the second time, and then input into the acousto-optic modulator, thereby improving the output power of the laser after entering the acousto-optic modulator for frequency reduction processing, ensuring that the pulsed laser with higher signal light power is input into the subsequent optical fiber amplifier for amplification, thereby ensuring the power amplification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a schematic structural diagram of a pulse laser regulation system according to a first embodiment of the present invention;

[0026] Figure 2 It is a structural diagram of the pulse laser regulation system in the second embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] Ultrafast laser systems currently used in precision machining generally include five components, arranged in sequence: a seed source, a pulse stretcher, an acousto-optic modulator, a pulse power amplifier module, and a pulse compression module. However, if the seed source's pulse laser is directly input into the pulse stretcher to achieve the effect of pulse stretching, the output power of the stretched laser pulse will be significantly reduced due to the relatively low reflectivity of the pulse stretcher. Furthermore, if the stretched laser pulse is directly input into the acousto-optic modulator for frequency reduction, its final output power will be greatly reduced, especially when the repetition frequency of the laser pulse is reduced to the kHz level, its output power will drop avalanche-like. At the same time, if the frequency-reduced pulse laser is directly input into the pulse power amplifier module for amplification, the power amplification effect will be greatly affected due to the low signal light power.

[0029] Therefore, the purpose of the present invention is to propose a pulse laser regulation system that integrates broadening, pre-amplification and frequency selection. By using this solution to build an ultrafast laser, an ultrafast pulse laser output with a compact structure, good stability and low cost can be obtained.

[0030] Example 1

[0031] See also Figure 1 , shown is a pulse laser regulation system in embodiment 1 of the present invention, which includes a laser seed source 1, a polarization-maintaining circulator 2, a fiber pre-amplifier 3, a laser pulse stretcher 4, an acousto-optic modulator 5, a fiber amplifier 6 and a pulse frequency selection module 7.

[0032] In this embodiment, the laser seed source 1 is specifically an ultrafast laser seed source 1, which is used to emit an ultrafast laser signal. The polarization-maintaining circulator 2 has an incident end 21, a first emission end 22, and a second emission end 23. The laser seed source 1 and the incident end 21 of the polarization-maintaining circulator 2 are located on the same optical path. The first emission end 22, the fiber preamplifier 3, and the laser pulse stretcher 4 are sequentially arranged on the same optical path. The second emission end 23, the acousto-optic modulator 5, and the fiber amplifier 6 are sequentially arranged on the same optical path.

[0033] Specifically, after being emitted from the laser seed source 1, the laser is first injected into the incident end 21 of the polarization-maintaining circulator 2 and emitted through the first emission end 22 of the polarization-maintaining circulator 2, and then injected into the fiber pre-amplifier 3 for amplification. The pre-amplified laser is injected into the laser pulse stretcher 4 for pulse stretching. Due to the reflection effect of the laser pulse stretcher 4, the laser after stretching will enter the fiber pre-amplifier 3 again for secondary amplification, and then injected into the first emission end 22 of the polarization-maintaining circulator 2 and emitted from the second emission end 23 of the polarization-maintaining circulator 2, and then injected into the acousto-optic modulator 5 for frequency reduction processing, and finally amplified by the fiber amplifier 6 and output.

[0034] Specifically, the fiber preamplifier 3 includes a first pump source 31, a first polarization-maintaining wavelength division multiplexer 32, and a first polarization-maintaining active fiber 33. The first output port 22, the first polarization-maintaining wavelength division multiplexer 32, the first polarization-maintaining active fiber 33, and the laser pulse stretcher 4 are sequentially arranged on the same optical path. The transmit signal from the first pump source 31 and the laser signal emitted from the first output port 22 are combined into a laser beam by the first polarization-maintaining wavelength division multiplexer 32 and then injected into the first polarization-maintaining active fiber 33. The fiber amplifier 6 includes a second pump source 61, a second polarization-maintaining wavelength division multiplexer 62, and a second polarization-maintaining active fiber 63. The second output port 23, the acousto-optic modulator 5, the second polarization-maintaining wavelength division multiplexer 62, and the second polarization-maintaining active fiber 63 are sequentially arranged on the same optical path. The transmit signal from the second pump source 61 and the laser signal emitted from the acousto-optic modulator 5 are combined into a laser beam by the second polarization-maintaining wavelength division multiplexer 62 and then injected into the second polarization-maintaining active fiber 63.

[0035] The pulse frequency selection module 7 is used to select the frequency of the RF signal based on the laser seed source 1 and the acousto-optic modulator 5. Specifically, in conjunction with the ultrafast seed source pulse synchronization signal, by adjusting the pulse frequency selection module 7, the target RF signal can be obtained to drive the acousto-optic modulator 5, ultimately achieving a pulsed laser output below kilohertz. Due to the reduction in the repetition frequency of the pulsed laser, the output power of the pulsed laser after frequency selection will also be greatly reduced. In order to better perform high-power amplification of the laser pulses later, the laser pulses after frequency selection need to be pre-amplified.

[0036] In a specific implementation, the pulse frequency selection module 7 can be a central processing unit (CPU), a microcontroller unit (MCU), or directly a control circuit board. It can receive the synchronous RF signal of the seed source. In this case, the pulse frequency selection module 7 can be set to output a radio frequency signal lower than the synchronous RF signal of the seed source to the acousto-optic modulator 5. This radio frequency signal has a certain repetition frequency, voltage amplitude, and time width. When this radio frequency signal is input to the acousto-optic modulator 5, it is equivalent to a gate signal, which determines the on and off of the laser. Within the set time width, the laser passes through the acousto-optic modulator 5. During other time widths, the laser is blocked and cannot pass through. In this way, it plays a role in frequency selection of the laser pulse.

[0037] In summary, the pulse laser regulation system in this embodiment, by providing a polarization-maintaining circulator 2 and a fiber pre-amplifier 3, allows the laser to be input into the laser pulse stretcher 4 after pre-amplification, thereby improving the output power of the pulsed laser after entering the laser pulse stretcher 4 for pulse stretching. Due to the reflection effect of the laser pulse stretcher 4, the laser after stretching will enter the fiber pre-amplifier 3 again, and then the laser will be amplified for the second time, and then input into the acousto-optic modulator 5, thereby improving the output power of the laser after entering the acousto-optic modulator 5 for frequency reduction processing, ensuring that the pulsed laser with higher signal light power is input into the subsequent fiber amplifier 6 for amplification, thereby ensuring the power amplification effect and greatly improving the signal-to-noise ratio of the spectrum.

[0038] Example 2

[0039] See also Figure 2 , which shows the pulse laser regulation system in the second embodiment of the present invention. The difference between the pulse laser regulation system in this embodiment and the pulse laser regulation system in the first embodiment is that:

[0040] The fiber amplifier 6 also includes a polarization-maintaining filter 64 and a polarization-maintaining isolator 65. The fiber amplifier 6 and the polarization-maintaining filter 64 are sequentially arranged on the same optical path. The polarization-maintaining filter 64 is used to filter out fluorescence signals from the laser signal emitted by the fiber amplifier 6. The polarization-maintaining filter 64 and the polarization-maintaining filter 65 are sequentially arranged on the same optical path. After the fluorescence is filtered out by the polarization-maintaining filter 64, the laser signal is emitted through the polarization-maintaining isolator 65. The addition of the polarization-maintaining filter 64 to the fiber amplifier 6 can filter out fluorescence generated during the amplification process, further improving the signal-to-noise ratio of the spectrum. The polarization-maintaining isolator 65 is added to ensure unidirectional transmission of the laser pulses.

[0041] The present invention proposes a design scheme for a pulse laser regulation device integrating pulse broadening, pre-amplification, and frequency selection. This scheme is suitable for pulse broadening, power pre-amplification, and pulse frequency selection of ultrafast lasers at 1030nm, 1064nm, 1550nm, and 1960nm. By using this scheme, a low-repetition-rate pulse laser output with a compact structure, good stability, and a high signal-to-noise ratio can be obtained.

[0042] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pulse laser adjustment system, characterized in that: The system comprises: A laser seed source, used for emitting laser signals; A polarization-maintaining circulator having an incident end, a first emitting end, and a second emitting end, wherein the laser seed source and the incident end of the polarization-maintaining circulator are on the same optical path; An optical fiber pre-amplifier and a laser pulse stretcher, wherein the first emission end, the optical fiber pre-amplifier and the laser pulse stretcher are sequentially arranged on the same optical path; an acousto-optic modulator and an optical fiber amplifier, wherein the second emission end, the acousto-optic modulator and the optical fiber amplifier are sequentially arranged on the same optical path; Among them, after the laser signal is emitted from the laser seed source, it first enters the incident end of the polarization-maintaining circulator and is emitted through the first emission end of the polarization-maintaining circulator, and then enters the fiber pre-amplifier for amplification. The pre-amplified laser enters the laser pulse stretcher for pulse stretching. After the stretching is completed, the laser will be reflected by the laser pulse stretcher and will enter the fiber pre-amplifier again for secondary amplification. It is then injected into the first emission end of the polarization-maintaining circulator and emitted from the second emission end of the polarization-maintaining circulator, and then injected into the acousto-optic modulator for frequency reduction processing, and finally amplified by the fiber amplifier and output.

2. The pulse laser adjustment system according to claim 1, characterized in that: The optical fiber pre-amplifier includes a first pump source, a first polarization-maintaining wavelength division multiplexer, and a first polarization-maintaining active optical fiber; Wherein, the first emission end, the first polarization-maintaining wavelength division multiplexer, the first polarization-maintaining active optical fiber, and the laser pulse stretcher are sequentially arranged on the same optical path; The emission signal of the first pump source and the laser signal emitted from the first emission end are combined into one laser signal through the first polarization-maintaining wavelength division multiplexer and then emitted into the first polarization-maintaining active optical fiber.

3. The pulse laser modulation system according to claim 1, characterized in that: The optical fiber amplifier includes a second pump source, a second polarization-maintaining wavelength division multiplexer, and a second polarization-maintaining active optical fiber; The second emission end, the acousto-optic modulator, the second polarization-maintaining wavelength division multiplexer, and the second polarization-maintaining active optical fiber are sequentially arranged on the same optical path; The emission signal of the second pump source and the laser signal emitted from the acousto-optic modulator are combined into one laser signal through the second polarization-maintaining wavelength division multiplexer and then emitted into the second polarization-maintaining active optical fiber.

4. The pulse laser adjustment system according to claim 3, characterized in that: The optical fiber amplifier further includes a polarization-maintaining filter, and the optical fiber amplifier and the polarization-maintaining filter are sequentially arranged on the same optical path; The polarization-maintaining filter is used to filter out the fluorescence signal in the laser signal emitted by the optical fiber amplifier.

5. The pulse laser adjustment system according to claim 4, characterized in that: The optical fiber amplifier further comprises a polarization-maintaining isolator, and the polarization-maintaining filter and the polarization-maintaining filter are sequentially arranged on the same optical path; The laser signal after the fluorescence is filtered out by the polarization-maintaining filter is emitted through the polarization-maintaining isolator.

6. The pulse laser modulation system according to any one of claims 1 to 5, characterized in that: The pulse laser adjustment system also includes: A pulse frequency selection module is used to select the frequency of the radio frequency signal according to the laser seed source and the acousto-optic modulator.

7. The pulse laser modulation system according to any one of claims 1 to 5, characterized in that: The laser seed source is an ultrafast laser seed source.

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