A device for pulse division of a pulsed laser
By using a pulse splitter for a pulsed laser, utilizing the Pockel cell and polarization characteristics, and combining digital delay signal control, the space and cost issues of increasing the repetition frequency of femtosecond lasers have been solved, achieving improvements in stability and economy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI INST OF LASER PLASMA CHINA ACAD OF ENG PHYSICS
- Filing Date
- 2025-05-07
- Publication Date
- 2026-06-09
AI Technical Summary
Existing femtosecond lasers suffer from problems such as large space occupation, instability and high cost when increasing the repetition rate, making it difficult to achieve precise control while ensuring high laser power.
A pulse splitting device using a pulsed laser is employed. By leveraging the electro-optic modulation and polarization characteristics of a Pockel cell, combined with a digital delay pulse signal generator and a high-voltage pulse generator, stable pulse splitting and output are achieved, simplifying components and reducing costs.
It achieves an increase in laser repetition frequency, good structural stability, and cost savings, while avoiding the space occupation of elongated regeneration amplification cavity, and is suitable for various pulsed lasers.
Smart Images
Figure CN224342732U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of laser technology, specifically to a device for pulse splitting of a pulsed laser. Background Technology
[0002] Femtosecond lasers are used in precision machining, medical diagnostics, fiber optic communication and other fields. Femtosecond lasers usually use passive mode-locking to generate ultrashort pulses. If you want to increase the repetition frequency while ensuring the high power of the laser, you need to lengthen the regenerative amplification cavity. This method results in a large overall space for the femtosecond laser. At the same time, there are unstable factors in the resonant cavity, which leads to large jitter in the pulse timing and cannot achieve precise control.
[0003] In addition, high-repetition-rate femtosecond lasers on the market are generally very expensive, making them costly and not cost-effective for most research institutions and universities. Therefore, it is essential to find a stable, efficient and economical method to increase the laser repetition rate. Utility Model Content
[0004] To achieve the above-mentioned technical objectives, this utility model provides a device for pulse splitting of pulse lasers, which can increase the repetition frequency of pulse lasers, ensure structural stability, and save costs to a certain extent.
[0005] The technical objective of this utility model is achieved through the following technical solution:
[0006] A device for pulse splitting of a pulsed laser, comprising:
[0007] A pulsed laser is used to emit a laser beam.
[0008] Along the direction of the laser beam emission of the pulsed laser, a laser attenuation device, a laser beam shrinking device, a laser polarization device, a waveplate, a Pockels cell, an output mirror, and a waveform detection device are arranged in sequence. The output mirror is used to output the first beam to the waveform detection device and reflect the second beam back to the original optical path.
[0009] A total reflection mirror is also configured on one side of the laser polarization device to cooperate with the laser polarization device to form a second beam that is reflected to the laser polarization device and then propagates along the original optical path emission direction after reaching the laser polarization device.
[0010] The Pockel cell is connected to a high-voltage pulse generator that provides voltage pulses to the Pockel cell. The pulsed laser is also connected to a digital delay pulse signal generator. The digital delay pulse signal generator sends a synchronization signal to the high-voltage pulse generator when the laser beam emitted by the pulsed laser reaches the Pockel cell, so as to control the high-voltage pulse generator to generate voltage pulses.
[0011] Furthermore, the pulsed laser is a femtosecond laser, and the laser pulse width of the laser beam emitted by the femtosecond laser ranges from 200fs to 250fs, with a repetition frequency of 33kHz.
[0012] Furthermore, the waveplate is a quarter-wave plate.
[0013] Furthermore, the laser attenuation device includes a polarizer and a half-wave plate.
[0014] Furthermore, the laser beam-shrinking device includes a convex lens and a concave lens, with a beam-shrinking ratio of 3:1 to 4:1.
[0015] Furthermore, both the convex and concave lenses are 0° working lenses.
[0016] Furthermore, the laser polarization device is a polarizer.
[0017] Furthermore, the output mirror has a transmittance of 3% and a reflectivity of 97% for the laser beam.
[0018] Furthermore, the working angle of the total reflection mirror is 0°.
[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0020] 1. This application achieves stable control and output of pulse splitting by utilizing the electro-optic modulation and polarization characteristics of the Pockel cell. Compared with traditional methods of increasing laser repetition frequency, this method is simpler, uses fewer components, and reduces costs while ensuring stability. At the same time, it eliminates the need to lengthen the regenerative amplification cavity, thus avoiding increased space occupation.
[0021] 2. The femtosecond laser pulse splitting device of this application can be applied not only to femtosecond lasers, but also to various pulsed lasers such as nanosecond and picosecond lasers, and has a wide range of applicability. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the pulse train splitting device of the present invention.
[0023] Figure 2 This is a schematic diagram of the laser attenuation device in this utility model.
[0024] Figure 3 This is a schematic diagram of the pulse signal emitted by the femtosecond laser in an embodiment of this utility model.
[0025] Figure 4 This is a schematic diagram of the pulse signal after pulse splitting in this utility model.
[0026] In the picture:
[0027] 1. Digital delay pulse generator; 2. Pulsed laser; 3. Laser attenuation device; 4. Laser beam shrinking device; 5. Laser polarization device; 6. Quarter-wave plate; 7. Pockels cell; 8. Output mirror; 9. Waveform detection device; 10. High-voltage pulse generator; 11. High-voltage power supply; 12. Total reflection mirror; 13. Polarizer; 14. Half-wave plate; 15. Convex lens; 16. Concave lens. Detailed Implementation
[0028] The technical solution of this utility model will be further described below with reference to specific embodiments:
[0029] A device for splitting pulses in a pulsed laser, such as Figure 1 As shown, it includes:
[0030] Pulsed laser 2 is used to emit a pulsed laser beam. Pulsed laser 2 can be a femtosecond laser, nanosecond laser, picosecond laser, or other pulsed lasers. In this embodiment, a femtosecond laser is used as an example.
[0031] Along the laser beam emission direction of the pulsed laser 2, a laser attenuation device 3, a laser beam shortening device 4, a laser polarization device 5, a quarter-wave plate 6, a Pockels cell 7, an output mirror 8, and a waveform detection device 9 are arranged sequentially. The output mirror 8 is used to output the first beam to the waveform detection device 9 and reflect the second beam back to the original optical path. The output mirror, also called a partial reflector, is an existing optical device. The output mirror 8 has a laser beam transmittance of 3% and a reflectivity of 97%. The waveform detector 9 has a photoelectric probe and a digital oscilloscope to display the detected waveform.
[0032] A total reflection mirror 12 is also configured on one side of the laser polarization device 5 to cooperate with the laser polarization device 5 to form a total reflection mirror 12 for the second beam to be reflected and propagated along the original optical path emission direction after reaching the laser polarization device 5. The working angle of the total reflection mirror is 0°. The total reflection mirror must be directly facing the reflected laser to ensure perpendicular incidence. The distance between the total reflection mirror and the laser polarization device 5 is about 1-2m.
[0033] The Pockel box 7 is connected to a high-voltage pulse generator 10, which provides voltage pulses to the Pockel box 7. In use, the high-voltage pulse generator is connected to a high-voltage power supply 11. The pulsed laser 2 is also connected to a digital delay pulse signal generator 1. The digital delay pulse signal generator 1 is used to send a synchronization signal to the high-voltage pulse generator 10 when the laser beam emitted by the pulsed laser 2 reaches the Pockel box 7, so as to control the high-voltage pulse generator 10 to generate voltage pulses.
[0034] More specifically, the laser beam emitted by the pulsed laser 2 has a laser pulse width range of 200fs-250fs and a repetition frequency of 33kHz.
[0035] The laser attenuation device 3 includes a polarizer 13 and a half-wave plate 14, such as Figure 2 As shown, after the laser beam emitted by the pulsed laser 2 passes through the half-wave plate 14 and the polarizer 13 of the laser attenuation device in sequence, part of the laser beam is reflected, and the remaining laser beam propagates towards the laser beam shrinking device 4.
[0036] The laser beam-shrinking device 4 includes a convex lens 15 and a concave lens 16, with a beam-shrinking ratio of 3:1 to 4:1. The attenuated laser beam passes through the convex lens 15 and the concave lens 16 in sequence, resulting in beam shrinkage. Both the convex lens 15 and the concave lens 16 are 0° working lenses. In actual placement, they need to be offset by a slight angle to prevent back-reflected light. In a specific implementation, it is only necessary to rotate the lenses 1-2° left or right.
[0037] The laser polarization device 5 is a polarizer, and the angle at which the polarizer of the laser polarization device 5 is placed is the angle at which the intensity of the light reflected by the polarization device is at its minimum.
[0038] To better understand the process in this application, the work process is described as follows:
[0039] The pulsed laser 2 emits a pulsed laser beam, which passes sequentially through the laser attenuation device 3, the laser beam shrinking device 4, the laser polarization device 5, the quarter-wave plate 6, and the Pockel cell 7. After propagating to the output mirror 8, it splits into two beams, namely the first beam and the second beam. The first beam continues to propagate to the waveform detection device 9, where it is captured to form the first light pulse of the split sequence. The second beam then propagates in the opposite direction along the original optical path.
[0040] The second beam propagates in the reverse direction along the original optical path, passing through the Pockel cell 7 and the quarter-wave plate 6 in sequence before reaching the laser polarization device 5. Under the reflection of the laser polarization device 5, the second beam propagates to the total reflection mirror 12, and then propagates to the laser polarization device 5 after being reflected by the total reflection mirror 12. The propagation direction of the second beam changes to propagate towards the output mirror.
[0041] The second beam is reflected back to the laser polarization device 5 by the total reflection mirror 12, and then propagates through the quarter-wave plate 6 and the Pockel cell 7 in sequence. After propagating to the output mirror 8, it splits into two beams, namely the third beam and the fourth beam. The third beam continues to propagate to the waveform detection device 9, where it is captured to form the second light pulse in the split sequence. The fourth beam then propagates in the opposite direction along the original optical path.
[0042] The fourth beam propagates in the reverse direction along the original optical path, passing through the Pockel cell 7 and the quarter-wave plate 6 in sequence before reaching the laser polarization device 5. Under the reflection of the laser polarization device 5, the fourth beam propagates to the total reflection mirror 12, and then propagates to the laser polarization device 5 after being reflected by the total reflection mirror 12. The direction of the fourth beam changes to propagate towards the output mirror.
[0043] After the fourth beam is reflected back to the laser polarization device 5 by the total reflection mirror 12, it propagates sequentially through the quarter-wave plate 6 and the Pockel cell 7, and then splits into two beams, namely the fifth beam and the sixth beam, after reaching the output mirror 8. The fifth beam continues to propagate to the waveform detection device 9, where it is captured to form the third light pulse in the split sequence. The sixth beam then propagates in the opposite direction along the original optical path.
[0044] Following the process described above, the fourth, fifth, and sixth light pulses are formed in sequence, and so on. This will not be elaborated further here.
[0045] In the aforementioned propagation process, a synchronization signal (delay amount) is sent to the high-voltage pulse generator 10 via the digital delay pulse signal generator 1, enabling the high-voltage pulse generator 10 to provide a high-voltage pulse to the Pockel cell. The amount of delay is adjusted by the waveform detected by the waveform detector, thereby ensuring that the Pockel cell is in working condition each time the beam reflected by the output mirror 8 reaches it, thus achieving the purpose of pulse splitting and increasing the repetition frequency of the pulsed laser. Figure 3 As shown, the pulse signal interval of the femtosecond laser is Δt. Within the range of Δt, the pulse signal is divided into multiple equally spaced pulse signals, such as... Figure 4 As shown. Within each Δt range, the number of pulse signals emitted by the femtosecond laser can be precisely controlled by adjusting the delay provided by the digital delay pulse generator, which can be used to precisely control the number of subsequent pulse trains output.
[0046] When the pulsed laser is a nanosecond laser or a picosecond laser, time-domain synchronization can be ensured by adjusting the digital delay pulse generator and the Pockel cell, which will not be elaborated here.
[0047] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make non-inventive modifications to this embodiment as needed, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.
Claims
1. A device for splitting pulses in a pulsed laser, characterized in that, include: A pulsed laser is used to emit a laser beam. Along the direction of the laser beam emission of the pulsed laser, a laser attenuation device, a laser beam shrinking device, a laser polarization device, a waveplate, a Pockels cell, an output mirror, and a waveform detection device are arranged in sequence. The output mirror is used to output a first beam to the waveform detection device and reflect a second beam back to the original optical path. A total reflection mirror is also configured on one side of the laser polarization device to cooperate with the laser polarization device to form a total reflection mirror that, after the second beam is reflected to the laser polarization device, propagates along the original optical path emission direction. The Pockel cell is connected to a high-voltage pulse generator for providing voltage pulses to the Pockel cell. The pulsed laser is also connected to a digital delay pulse signal generator. The digital delay pulse signal generator is used to send a synchronization signal to the high-voltage pulse generator when the laser beam emitted by the pulsed laser reaches the Pockel cell, so as to control the high-voltage pulse generator to generate voltage pulses.
2. The device for pulse train splitting of a pulsed laser according to claim 1, characterized in that, The pulsed laser is a femtosecond laser, and the laser pulse width of the laser beam emitted by the femtosecond laser ranges from 200fs to 250fs, with a repetition frequency of 33kHz.
3. The device for pulse train splitting of a pulsed laser according to claim 1, characterized in that, The waveplate is a quarter-wave plate.
4. The device for pulse train splitting of a pulsed laser according to claim 1, characterized in that, The laser attenuation device includes a polarizer and a half-wave plate.
5. The device for pulse train splitting of a pulsed laser according to claim 1, characterized in that, The laser beam-shrinking device includes a convex lens and a concave lens, with a beam-shrinking ratio of 3:1 to 4:
1.
6. The apparatus for pulse train splitting of a pulsed laser according to claim 5, characterized in that, Both the convex lens and the concave lens are 0° working lenses.
7. The apparatus for pulse train splitting of a pulsed laser according to claim 1, characterized in that, The laser polarization device is a polarizer.
8. The apparatus for pulse train splitting of a pulsed laser according to claim 1, characterized in that, The output mirror has a transmittance of 3% and a reflectivity of 97% for the laser beam.
9. The apparatus for pulse train splitting of a pulsed laser according to claim 1, characterized in that, The working angle of the total reflection mirror is 0°.