A high-repetition-rate pulsed output fiber laser device

Abstract

The utility model relates to a kind of high-repetition-frequency pulse output's optical fiber laser device, including: seed source and optical fiber ring, the output end of the seed source is optically connected with the input end of the optical fiber ring;The optical fiber ring includes: 2x2 optical fiber coupler, combiner, pump source, doped optical fiber and amplitude modulator, wherein, the first input port of the 2x2 optical fiber coupler is the input end of the optical fiber ring, for receiving the input pulse of the seed source, the first output port of the 2x2 optical fiber coupler is one of total output end, for outputting the pulse sequence after increasing frequency, the second output port of the 2x2 optical fiber coupler is optically connected with the signal input end of the combiner, the output end of the combiner is optically connected with the input end of the doped optical fiber, the output end of the doped optical fiber is optically connected with the optical input end of the amplitude modulator.

Description

Technical Field

[0001] This utility model relates to the field of laser devices, specifically to a fiber laser device with high repetition rate pulse output. Background Technology

[0002] High repetition rate ultrashort pulse fiber lasers have wide applications in industrial micromachining, scientific research, and medical aesthetics. Especially in the field of ultrafast laser processing, the Burst pulse mode (also known as the pulse train mode) can effectively reduce the heat-affected zone during processing by decomposing a high-energy pulse into multiple consecutive low-energy sub-pulse sequences, and significantly improve the processing quality and precision of brittle and transparent materials such as glass, quartz, and sapphire. The prerequisite for realizing the Burst pulse mode is to obtain high repetition rate pulse light.

[0003] Currently, there are two main technical solutions for achieving high repetition rate pulse output, but both have significant limitations: The first approach relies on the characteristics of the laser oscillator itself. By shortening the physical length of the laser resonant cavity and increasing the pump power, the pulse repetition frequency of the seed source output can be increased to some extent. However, this method is limited by the power tolerance limit of the saturable absorber in the cavity, and its ability to increase the repetition frequency is limited, which cannot meet the need for higher repetition rates in many applications.

[0004] The second approach is based on extracavity pulse processing technology, which can also generate higher repetition frequencies. Existing technology typically splits an optical pulse into two pulse signal beams using a 1x2 fiber coupler, and then combines them using another fiber coupler with the same parameters. By controlling the difference in the length of the two fibers between the two 1x2 fiber couplers, the two pulse beams are staggered, thereby obtaining a pulse signal beam with twice the initial pulse repetition frequency. To maintain the same peak power of the two signal beams with a time difference, a fiber attenuator needs to be added to the optical path of the higher-power pulse signal beam. However, the fiber attenuator is essentially an adjustable mechanical component, and its long-term stability is difficult to guarantee, resulting in the peak power of two adjacent pulses in the final output pulse series not being consistent.

[0005] It is evident that existing technologies are either limited by the performance limits of core components, cannot escape dependence on high repetition rate seed sources, or introduce unstable mechanical adjustment parts, making it difficult to simultaneously achieve high stability, low cost, and high flexibility in high repetition rate pulse output. Therefore, a novel technical solution is urgently needed to overcome these technical shortcomings. Utility Model Content

[0006] Based on this, and in response to the above problems, this utility model provides a fiber laser device with high repetition rate pulse output, which adopts an all-fiber structure, greatly improving the stability and flexibility of high repetition rate pulse output.

[0007] To achieve the above objectives, this utility model provides a fiber laser device with high repetition rate pulse output, comprising: a seed source and a fiber ring, wherein the output end of the seed source is optically connected to the input end of the fiber ring; the fiber ring comprises: a 2x2 fiber coupler, a combiner, a pump source, a doped fiber, and an amplitude modulator, wherein the first input port of the 2x2 fiber coupler is the input end of the fiber ring, used to receive the input pulse from the seed source; the first output port of the 2x2 fiber coupler is one of the total output ends, used to output a pulse sequence with increased frequency; the second output port of the 2x2 fiber coupler is optically connected to the signal input end of the combiner; the output end of the combiner is optically connected to the input end of the doped fiber; the output end of the doped fiber is optically connected to the optical input end of the amplitude modulator; the optical output end of the amplitude modulator is optically connected to the second input port of the 2x2 fiber coupler, thereby forming an optical loop; the output end of the pump source is optically connected to the pump input end of the combiner; and the electrical control end of the amplitude modulator is used to receive external driving signals.

[0008] In one specific embodiment, a driving circuit is further included; the signal detection terminal of the driving circuit is electrically connected to the output terminal of the seed source, and is used to acquire the seed pulse as a pulse trigger signal; the signal output terminal of the driving circuit is connected to the electrical control terminal of the amplitude modulator, and is used to output a driving signal synchronized with the pulse trigger signal to the amplitude modulator.

[0009] In one specific embodiment, the splitting ratio of the 2x2 fiber coupler is not 50:50, and the optical power output from its second output port is lower than the optical power output from its first output port.

[0010] In one specific embodiment, the cavity length of the fiber optic ring is L = c / (n*f). out ), where c is the speed of light in a vacuum, n is the refractive index of the optical fiber, and f out The output pulse repetition frequency is N times the pulse repetition frequency of the seed source, where N is a positive integer greater than 1.

[0011] In one specific embodiment, the multiplexer is a wavelength division multiplexer or a pumped beam combiner.

[0012] In one specific embodiment, the doped optical fiber is a ytterbium-doped optical fiber, an erbium-doped optical fiber, a thulium-doped optical fiber, a holmium-doped optical fiber, or an erbium-ytterbium co-doped optical fiber.

[0013] In one specific embodiment, the amplitude modulator is an acousto-optic modulator, an electro-optic modulator, or an optical switch.

[0014] In one specific embodiment, the pump source is a laser diode or fiber laser with adjustable output power, used to compensate for optical signal loss in the optical loop by adjusting the pump power, so as to maintain the stability of pulse energy.

[0015] In one specific embodiment, the wavelength of the pump light output by the pump source is within the wavelength range corresponding to the absorption cross section of the doped fiber; the wavelength of the signal light output by the seed source is within the wavelength range corresponding to the emission cross section of the doped fiber.

[0016] In one specific embodiment, the pump light output from the pump source has a wavelength of 915nm or 976nm; the signal light output from the seed source has a wavelength of 1064nm or 1550nm.

[0017] Compared with the prior art, the beneficial effects of this utility model are: This invention constructs an optical fiber loop with active gain compensation, employing an all-fiber structure. It requires no mechanical structure and does not alter the resonant cavity length of the seed source or the power handling capacity of the saturable absorber. It generates pulsed light with a repetition frequency N times that of the seed source. A 2x2 fiber coupler is used for beam splitting, injecting a portion of the seed pulse's energy into the fiber loop. The pulse circulates within the loop, superimposing with a newly injected pulse after each cycle and outputting it once from the main output. This cyclic multiplexing and amplification of the low-repetition-rate seed pulse allows for the replication of multiple pulses in the time domain, achieving frequency multiplication. The doped fiber in the loop ensures that the pulse energy is not lost during the cycle but is maintained or enhanced. This embodiment realizes an all-fiber repetition-rate multiplier with high system stability and integration, providing high-quality high-repetition-rate pulse sequences and significantly reducing the system's dependence on a high-repetition-rate seed source. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a fiber laser device with high repetition rate pulse output according to the present invention.

[0019] Figure 2 This is a schematic diagram comparing the repetition rates of the seed source pulse and the modulated output pulse of this invention. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0021] like Figure 1 As shown, this embodiment provides a fiber laser device with high repetition rate pulse output, including: a seed source 1 and a fiber ring 2. The output end of the seed source 1 is optically connected to the input end of the fiber ring 2. The fiber ring 2 includes: a 2x2 fiber coupler 21, a combiner 22, a pump source 23, a doped fiber 24, and an amplitude modulator 25. The first input port of the 2x2 fiber coupler 21 is the input end of the fiber ring 2, used to receive the input pulse from the seed source 1, and the first output port of the 2x2 fiber coupler 21 is the overall output end. One of the components is used to output a pulse sequence with increased frequency. The second output port of the 2x2 fiber coupler 21 is optically connected to the signal input port of the combiner 22. The output port of the combiner 22 is optically connected to the input port of the doped fiber 24. The output port of the doped fiber 24 is optically connected to the optical input port of the amplitude modulator 25. The optical output port of the amplitude modulator 25 is optically connected to the second input port of the 2x2 fiber coupler 21, thus forming an optical loop. The output port of the pump source 23 is connected to the combiner... The pump input of the amplifier 22 is optically connected, and the electrical control terminal of the amplitude modulator 25 is used to receive external driving signals. This invention constructs an optical fiber loop with active gain compensation, adopting an all-fiber structure. It requires no mechanical structure and does not need to change the resonant cavity length of the seed source or the power handling capacity of the saturable absorber. It can obtain pulsed light with a repetition frequency N times that of the seed source. A 2x2 optical fiber coupler 21 is used for beam splitting, injecting a portion of the seed pulse's energy into the optical fiber loop. The pulse circulates within the loop, and each cycle is superimposed with a newly injected pulse and output once from the main output. This cyclically multiplexes and amplifies the low-repetition-frequency seed pulse, thereby replicating multiple pulses in the time domain and achieving a doubling of the repetition frequency. The doped fiber in the loop ensures that the pulse energy is not lost during the cycle but is maintained or enhanced. This embodiment realizes an all-fiber repetition frequency multiplier with high system stability and high integration, providing a high-quality high-repetition-frequency pulse sequence and greatly reducing the system's dependence on the high-repetition-frequency seed source. A schematic diagram comparing the repetition frequencies of the seed source pulse and the modulated output pulse is shown below. Figure 2 As shown.

[0022] In one specific embodiment, a driving circuit (not shown in the figure) is also included. The signal detection terminal of the driving circuit is electrically connected to the output terminal of the seed source 1 to acquire the seed pulse as a pulse trigger signal. The signal output terminal of the driving circuit is connected to the electrical control terminal of the amplitude modulator 25 to output a driving signal synchronized with the pulse trigger signal to the amplitude modulator 25. The driving circuit acquires the beat reference of the entire system by detecting the seed pulse, ensuring that the switching action of the amplitude modulator is precisely synchronized with the arrival time of the pulse. This synchronization control is the key to achieving accurate selection of the number of pulses, ensuring strict synchronization between the output pulse sequence and the seed source, avoiding timing drift, providing a technical basis for actively and controllably generating high repetition rate pulses, and realizing functional flexibility.

[0023] In one specific embodiment, the splitting ratio of the 2x2 fiber coupler 21 is not 50:50, and the optical power output from its second output port is lower than that from its first output port. This asymmetric splitting design directly outputs most of the optical energy, ensuring the output efficiency of the system. A small portion of the energy enters the fiber loop for cyclic multiplication, which is sufficient to maintain the oscillation within the loop and avoids excessive energy circulation within the loop, which could cause nonlinear effects or waste. This significantly improves the energy utilization efficiency of the entire device, avoids excessively high power within the loop from damaging optical components or generating unnecessary nonlinear effects, and improves the reliability and stability of the system.

[0024] In one specific embodiment, the pulse light repetition frequency output by seed source 1 is f. in After passing through fiber loop 2, a pulse light with a repetition frequency N times that of the pulse light output from seed source 1 is obtained, denoted as f. out That is, the pulse interval time t = 1 / f out =1 / (N*f in Let t be the time required for the pulsed light to pass through the fiber optic ring. Then, the cavity length of the fiber optic ring can be obtained as L = c * t / n = c / (n * f). out )=c / (n*N*f in ), where c is the speed of light in a vacuum, n is the refractive index of the optical fiber, and N is a positive integer greater than 1.

[0025] In one specific embodiment, the multiplexer 22 is a wavelength division multiplexer or a pumped beam combiner.

[0026] In one specific embodiment, the doped optical fiber 24 is a ytterbium-doped optical fiber, an erbium-doped optical fiber, a thulium-doped optical fiber, a holmium-doped optical fiber, or an erbium-ytterbium co-doped optical fiber.

[0027] In one specific embodiment, the amplitude modulator 25 is an acousto-optic modulator, an electro-optic modulator, or an optical switch.

[0028] In one specific embodiment, the pump source 23 is a laser diode or fiber laser with adjustable output power, used to compensate for optical signal loss in the optical loop by adjusting the pump power, so as to maintain the stability of pulse energy.

[0029] The pump light output from the pump source 23 has a wavelength within the wavelength range corresponding to the absorption cross-section of the doped fiber 24; the signal light output from the seed source 1 has a wavelength within the wavelength range corresponding to the emission cross-section of the doped fiber 24. For example, the pump light output from the pump source has a wavelength of 915 nm or 976 nm; the signal light output from the seed source has a wavelength of 1064 nm or 1550 nm.

[0030] It should be noted that, for those skilled in the art, it is obvious that this utility model is not limited to the details of the above exemplary embodiments, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this utility model is defined by the appended claims rather than the foregoing description. Therefore, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model, and no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A fiber laser device with high repetition rate pulse output, characterized in that, include: Seed source (1) and fiber ring (2), wherein the output end of the seed source (1) is optically connected to the input end of the fiber ring (2); The fiber optic ring (2) includes: a 2x2 fiber coupler (21), a combiner (22), a pump source (23), a doped fiber (24), and an amplitude modulator (25). The first input port of the 2x2 fiber coupler (21) is the input port of the fiber optic ring (2) and is used to receive the input pulse from the seed source (1). The first output port of the 2x2 fiber coupler (21) is one of the total output ports and is used to output a pulse sequence with increased frequency. The second output port of the 2x2 fiber coupler (21) is connected to the signal input of the combiner (22). The output end of the combiner (22) is optically connected to the input end of the doped fiber (24), the output end of the doped fiber (24) is optically connected to the optical input end of the amplitude modulator (25), and the optical output end of the amplitude modulator (25) is optically connected to the second input port of the 2x2 fiber coupler (21), thereby forming an optical loop. The output end of the pump source (23) is optically connected to the pump input end of the combiner (22), and the electrical control end of the amplitude modulator (25) is used to receive external driving signals.

2. The fiber laser device with high repetition rate pulse output according to claim 1, characterized in that: It also includes a driving circuit: the signal detection terminal of the driving circuit is electrically connected to the output terminal of the seed source (1) to obtain the seed pulse as a pulse trigger signal, and the signal output terminal of the driving circuit is connected to the electrical control terminal of the amplitude modulator (25) to output a driving signal synchronized with the pulse trigger signal to the amplitude modulator (25).

3. The fiber laser device with high repetition rate pulse output according to claim 1, characterized in that: The splitting ratio of the 2x2 fiber coupler (21) is not 50:50, and the optical power output from its second output port is lower than that output from its first output port.

4. A fiber laser device with high repetition rate pulse output according to claim 1, characterized in that: The cavity length of the fiber optic ring is L = c / (n*f). out ), where c is the speed of light in a vacuum, n is the refractive index of the optical fiber, and f out The output pulse repetition frequency is N times the pulse repetition frequency of the seed source (1), where N is a positive integer greater than 1.

5. A fiber laser device with high repetition rate pulse output according to claim 1, characterized in that: The multiplexer (22) is a wavelength division multiplexer or a pumped multiplexer.

6. The fiber laser device with high repetition rate pulse output according to claim 1, characterized in that: The doped optical fiber (24) is a ytterbium-doped optical fiber, an erbium-doped optical fiber, a thulium-doped optical fiber, a holmium-doped optical fiber, or an erbium-ytterbium co-doped optical fiber.

7. A fiber laser device with high repetition rate pulse output according to claim 1, characterized in that: The amplitude modulator (25) is an acousto-optic modulator, an electro-optic modulator, or an optical switch.

8. A fiber laser device with high repetition rate pulse output according to any one of claims 1-7, characterized in that: The pump source (23) is a laser diode or fiber laser with adjustable output power, used to compensate for optical signal loss in the optical loop by adjusting the pump power, so as to maintain the stability of pulse energy.

9. A fiber laser device with high repetition rate pulse output according to any one of claims 1-7, characterized in that: The pump light output from the pump source (23) has a wavelength within the wavelength range corresponding to the absorption cross section of the doped fiber (24); the signal light output from the seed source (1) has a wavelength within the wavelength range corresponding to the emission cross section of the doped fiber (24).

10. A fiber laser device with high repetition rate pulse output according to any one of claims 1-7, characterized in that: The pump light output from the pump source (23) has a wavelength of 915nm or 976nm; the signal light output from the seed source (1) has a wavelength of 1064nm or 1550nm.

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