Multi-path delay amplification and independent gain control pulse train time domain envelope synthesis system

Abstract

The application provides a pulse train time domain envelope synthesis system with multiple delay amplification and independent gain control, which comprises a wide spectrum pulse seed source, a 1xM optical fiber beam splitter, M parallel delay amplification branches with different optical paths, an Mx1 optical fiber combiner, and N delay amplification units and electric control modules with different optical paths in each delay amplification branch, so as to construct a 1xMxN beam splitting-multiple delay independent gain control architecture, so that the wide spectrum seed pulse laser is first separated into branch level pulse sequences in the time domain through the M delay amplification branches, and then separated into time sequence independent sub-pulses through the N delay amplification units, and the gain parameters of each delay amplification unit are independently adjusted by combining the electric control module, so that the envelope of each sub-pulse is independently adjustable by only adjusting the gain ratio, and the pulse train with multiple complex time domain envelopes can be flexibly output.

Description

Technical Field

[0001] This invention relates to the field of fiber laser technology, and more particularly to a pulse train time-domain envelope synthesis system with multi-path delay amplification and independent gain control. Background Technology

[0002] In the field of industrial laser processing, MOPA (Master Oscillator Power Amplifier) ​​nanosecond pulsed fiber lasers have been widely used in various processes such as marking, cutting, welding, and surface treatment. Different processing materials and processes have different requirements for the time-domain waveform of laser pulses: for example, flat-top pulses are suitable for uniform heating scenarios, ramp pulses can achieve gradient thermal effects, and multi-step pulses can meet the fine processing requirements of special materials. In addition, replacing traditional single pulses with pulse trains composed of multiple sub-pulses can achieve better cold processing effects and thermal management capabilities in fields such as brittle material cutting, OLED (Organic Light-Emitting Diode) glass scribing, and semiconductor wafer scribing. The amplitude and timing distribution of each sub-pulse in the pulse train, i.e., the time-domain envelope, directly determines the final processing quality and production efficiency.

[0003] Currently, the mainstream pulse train generation and shaping schemes can be mainly divided into three categories: The first category is the pulse selection and intensity modulation scheme based on acousto-optic / electro-optic modulators. This scheme uses a high-speed external modulator to select and control the amplitude of continuous seed light or pulse sequence to generate the target pulse train envelope. However, this scheme is limited by the modulator response speed and extinction ratio, making it difficult to generate pulse trains with extremely short sub-pulse intervals and steep envelope changes. At the same time, the introduction of the external modulator will increase the system complexity and reduce long-term operational stability. The second category is the time-domain superposition scheme based on beam splitting-delaying-combining. This scheme generates pulse trains by splitting the signal pulse laser beam, applying different delays, and then superimposing them. However, the energy of each delayed pulse in this scheme is limited by a fixed beam splitting ratio and cannot be adjusted independently, making it difficult to achieve flexible switching of various multi-step pulse waveforms. The third category is the control scheme based on intracavity nonlinear effects. This scheme switches the soliton state in the mode-locked pulsed fiber laser by adjusting the polarization controller or pump power. This scheme also cannot flexibly control specific time-domain waveforms and has poor processing repeatability.

[0004] While the pulse train generation scheme based on beam splitting-delaying-combining has the inherent advantages of an all-fiber structure, its core drawback is that the energy ratio of each delayed pulse after beam splitting is completely determined by the fixed parameters of the beam splitter, lacking independent control over the pulse gain of each branch. On the one hand, it can only generate pulse sequences with symmetrical or regular amplitude, and cannot realize irregular or multi-step complex pulse envelopes. On the other hand, waveform switching requires replacing the beam splitter or delay fiber, making it impossible to achieve rapid switching in industrial production processes. Summary of the Invention

[0005] To address the aforementioned shortcomings and improvement needs of existing technologies, this invention provides a pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control, solving the core technical problem that existing all-fiber pulse train generation schemes cannot independently control the gain of each sub-pulse. This invention can flexibly generate pulse trains and independently control the amplitude of each sub-pulse in an all-fiber architecture. Switching the pulse train time-domain envelope only requires adjusting the pump power ratio of each branch, without replacing any optical components.

[0006] To solve the above technical problems, the present invention provides a pulse train time-domain envelope synthesis system with multi-path delay amplification and independent gain control, including a broadband pulse seed source, a 1×M fiber beam splitter, M parallel delay amplification branches with different optical path lengths between branches, and an M×1 fiber beam combiner, where M≥3 and is a positive integer. The input of the 1×M fiber beam splitter is connected to a broadband pulse seed source, and the M outputs are respectively connected to M delay amplification branches; the outputs of the M delay amplification branches are respectively connected to the M inputs of the M×1 fiber beam combiner. Each delay amplification branch is equipped with N parallel delay amplification units and an electronic control module, with different optical path lengths between units. N ≥ 3 and is a positive integer. The delay amplification unit is used to perform differentiated time-domain delay and power amplification processing on the signal light allocated to it in sequence to output sub-pulses. The electronic control module is used to independently adjust the gain parameters of each delay amplification unit to achieve independent control of the time-domain envelope of the sub-pulses.

[0007] Preferably, the broadband pulse seed source outputs a broadband seed pulse laser with a spectral width greater than 10 nm, and its output pigtail is connected to the input pigtail of a 1×M fiber optic beam splitter; the 1×M fiber optic beam splitter receives the broadband seed pulse laser, and outputs M-path sub-pulse lasers after evenly splitting its power.

[0008] Preferably, each delay amplification branch includes a first passive delay fiber and a sub-pulse amplification and shaping unit that are optically connected sequentially along the signal transmission direction. The first passive delay fiber is fused to one output end of a 1×M fiber splitter, and the output end of the sub-pulse amplification and shaping unit is optically connected to one input end of an M×1 fiber combiner.

[0009] Preferably, the lengths of the first passive delay fibers configured in each delay amplification branch are not equal, and their lengths increase from top to bottom in an arithmetic sequence along the arrangement direction of the delay amplification branches; the optical path difference formed between two adjacent delay amplification branches is greater than the coherence length of the sub-pulse laser.

[0010] Preferably, each sub-pulse amplification and shaping unit includes a 1×N fiber beam splitter, an N-channel delay amplification unit, an N×1 fiber beam combiner, and an electrical control module. The input end of the 1×N fiber beam splitter is fused to the first passive delay fiber to split the incoming single-path sub-pulse laser into N outputs at equal power. The N outputs of the 1×N fiber beam splitter are connected one-to-one with the inputs of the N delay amplification units, and the outputs of each delay amplification unit are connected one-to-one with the N inputs of the N×1 fiber combiner. The electrical control module is electrically connected to the semiconductor pump source in each delay amplification unit, and the gain of each delay amplification unit is independently controlled by adjusting the pump drive current.

[0011] Preferably, each delay amplification unit includes a second passive delay fiber, a gain fiber, a pump signal combiner, and a semiconductor pump source; In this configuration, one end of the second passive delay fiber is fused to one output end of the 1×N fiber splitter, and the other end is fused to the first end of the gain fiber; the signal input end of the pump signal combiner is fused to the second end of the gain fiber, the pump end is connected to the semiconductor pump source, and the output end is connected to one input end of the N×1 fiber combiner.

[0012] Preferably, the lengths of the second passive delay fibers configured in each delay amplification unit are not equal, and their lengths increase from top to bottom in an arithmetic sequence along the arrangement direction of the delay amplification units; the optical path difference formed by two adjacent delay amplification units is greater than the coherence length of the signal light input to a single delay amplification unit.

[0013] Preferably, the optical path difference between adjacent delay amplification units is smaller than the optical path difference between adjacent delay amplification branches.

[0014] Preferably, the gain fibers configured in each delay amplification unit have the same fiber specifications and length.

[0015] Preferably, all optical elements of the pulse train time-domain envelope synthesis system are polarization-maintaining fibers and devices; the broadband seed pulse laser is linearly polarized light, which propagates along the fast or slow axis of the polarization-maintaining fiber.

[0016] Beneficial Effects: This invention provides a pulse train time-domain envelope synthesis system with multi-path delay amplification and independent gain control. It constructs a 1×M×N beam splitting-multi-path delay independent gain control architecture by setting up a broadband pulse seed source, a 1×M fiber beam splitter, M parallel delay amplification branches with different optical path lengths, and an M×1 fiber combiner. Each delay amplification branch incorporates N delay amplification units with different optical path lengths and an electronic control module. This allows the broadband seed pulse laser to be split by the 1×M fiber beam splitter before entering the M delay amplification branches, where the differentiated optical path lengths separate it into branch-level pulse sequences in the time domain. Each branch-level pulse is then split and enters an N-channel delay amplification unit, where it is further separated into time-independent, non-overlapping sub-pulses. Combined with the electronic control module's ability to independently adjust the gain parameters of each delay amplification unit, the output amplitude and temporal shape of each sub-pulse can be precisely controlled. Thus, without the need for any electro-optic or acousto-optic modulators, complex pulse train envelopes with arbitrary amplitude distributions can be directly synthesized in the time domain as required. Finally, only the gain ratio of the M×N-channel delay amplification units needs to be adjusted to achieve independent and adjustable temporal envelopes of each sub-pulse within the pulse train, flexibly outputting various complex temporal envelope pulse trains with adjustable sub-pulse shapes. Attached Figure Description

[0017] Figure 1 This is an optical path structure diagram of the pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control provided by the present invention; Figure 2 This is an optical path diagram of the sub-pulse amplification and shaping unit in the pulse train time-domain envelope synthesis system with multi-path delay amplification and independent gain control provided by the present invention. In the attached figures: 100—Pulse train time-domain envelope synthesis system; 11—Broadband pulse seed source; 12—1×M fiber bundler; 101(i)—Delay amplification branch (M≥3, 1≤i≤M, M and i are both positive integers); 13(i)—First passive delay fiber; 14(i)—Sub-pulse amplification and shaping unit; 15—M×1 fiber bundler; 140(j)—Delay amplification unit; 141—1×N fiber bundler; 142(j)—Second passive delay fiber; 143(j)—Gain fiber; 144(j)—Pump signal bundler; 145(j)—Semiconductor pump source; 146—Electronic control module; 147—N×1 fiber bundler. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] To address the shortcomings of existing technologies, the key to this invention lies in a technical solution that combines a 1×M×N two-stage all-fiber splitting-multi-path delay structure with independent pump gain control for each path. This solution uses two stages of passive delay fibers of unequal length to progressively split a single seed pulse into non-overlapping sub-pulses in the time domain. Simultaneously, each delay amplification branch is equipped with an independently controllable gain amplification module. Leveraging the low coherence characteristics of the broadband seed pulse, the process of combining each stage ensures that only incoherent intensity superposition occurs. Therefore, there is no need to introduce additional amplitude modulation devices such as electro-optic modulators or acousto-optic modulators. This allows for flexible synthesis of the overall pulse train envelope and independent, precise control of the temporal shape of individual sub-pulses within the all-fiber structure. All waveform switching can be completed simply by adjusting the pump drive parameters, without modifying the system hardware.

[0020] Please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the overall structure of the pulse train time-domain envelope synthesis system 100 with multi-channel delay amplification and independent gain control provided by the present invention. Figure 2 The diagram shows the structure of a single sub-pulse amplification and shaping unit 14(i); the overall structure of the pulse train time-domain envelope synthesis system 100 includes a broadband pulse seed source 11, a 1×M fiber beam splitter 12, M parallel delay amplification branches 101(i) with different optical paths between branches, and an M×1 fiber beam combiner 15; where M≥3 and is a positive integer, i is the optical element corresponding to the i-th branch, and 1≤i≤M and is a positive integer.

[0021] In this embodiment of the invention, the input end of the 1×M fiber beam splitter 12 is connected to the broadband pulse seed source 11, and the M output ends are respectively connected to the input ends of the M delay amplification branches 101(i). The output ends of the M delay amplification branches 101(i) are respectively connected to the M input ends of the M×1 fiber combiner 15. The broadband pulse seed source 11 outputs a broadband seed pulse laser with a spectral width greater than 10nm. Its output pigtail is connected to the input pigtail of the 1×M fiber beam splitter 12. After receiving the broadband seed pulse laser, the 1×M fiber beam splitter 12 divides the power evenly and outputs M sub-pulse lasers, which are then sent to each delay amplification branch 101(i).

[0022] In this embodiment of the invention, each delay amplification branch 101(i) includes a first passive delay fiber 13(i) and a sub-pulse amplification and shaping unit 14(i) that are optically connected sequentially along the signal transmission direction. The input end of the first passive delay fiber 13(i) is fused to one output end of the 1×M fiber splitter 12, and the output end of the sub-pulse amplification and shaping unit 14(i) is optically connected to one input end of the M×1 fiber combiner 15.

[0023] Specifically, the lengths of the first passive delay fiber 13(i) configured in each delay amplification branch 101(i) are not equal, and the lengths increase from top to bottom in an arithmetic sequence along the arrangement direction of the delay amplification branch 101(i); wherein, the lengths of each first passive delay fiber 13(i) increase in an arithmetic sequence, which can accurately set a fixed and consistent time-domain time interval between adjacent branches, and controllably construct a sub-pulse sequence with uniform temporal arrangement.

[0024] In this embodiment of the invention, the optical path difference formed by the length difference of the first passive delay fiber 13(i) between two adjacent delay amplification branches 101(i) is greater than the coherence length of the sub-pulse laser. When the signal laser passes through the first passive delay fiber 13(i), a differentiated time-domain delay is applied. The length difference determines the time interval between adjacent sub-pulses in the pulse train. At the same time, this optical path difference design ensures that the M sub-pulses only have intensity superposition after being bundled by the M×1 fiber combiner 15, without interference.

[0025] In this embodiment of the invention, each delay amplification branch 101(i) is configured with N parallel delay amplification units 140(j) and an electronic control module 146, where N ≥ 3 and is a positive integer. The delay amplification unit 140(j) is used to perform differentiated time-domain delay and power amplification processing on the signal light allocated to it in sequence to output sub-pulses. The electronic control module 146 is used to independently adjust the gain parameters of each delay amplification unit 140(j) to achieve independent control of the time-domain envelope of the corresponding sub-pulse.

[0026] In this embodiment of the invention, each sub-pulse amplification and shaping unit 14(i) includes a 1×N fiber beam splitter 141, an N-channel delay amplification unit 140(j), an N×1 fiber beam combiner 147, and an electrical control module 146; wherein, N≥3 and is a positive integer, j is the optical element corresponding to the j-th branch, and 1≤j≤N and is a positive integer.

[0027] Specifically, the input end of the 1×N fiber beam splitter 141 is fused to the output end of the first passive delay fiber 13(i) to split the incoming single-path sub-pulse laser into N outputs with equal power. The N output ends of the 1×N fiber beam splitter 141 are connected one-to-one with the input ends of the N delay amplification units 140(j). The output ends of each delay amplification unit 140(j) are connected one-to-one with the N input ends of the N×1 fiber combiner 147. The electrical control module 146 is electrically connected to the semiconductor pump source 145(j) in each delay amplification unit 140(j) and the gain of each delay amplification unit 140(j) is independently controlled by adjusting the pump drive current.

[0028] Please see Figure 2Each delay amplification unit 140(j) includes a second passive delay fiber 142(j), a gain fiber 143(j), a pump signal combiner 144(j), and a semiconductor pump source 145(j). One end of the second passive delay fiber 142(j) is fused to one output end of a 1×N fiber splitter 141, and the other end is fused to the first end of the gain fiber 143(j). The signal input end of the pump signal combiner 144(j) is fused to the second end of the gain fiber 143(j), the pump end is optically connected to the semiconductor pump source 145(j), and the output end is optically connected to one input end of an N×1 fiber combiner 147.

[0029] In this embodiment of the invention, the lengths of the second passive delay fibers 142(j) configured in each delay amplification unit 140(j) are not equal, and the lengths increase from top to bottom in an arithmetic sequence along the arrangement direction of the delay amplification units 140(j). The optical path difference formed by the length difference of the second passive delay fibers 142(j) between two adjacent delay amplification units 140(j) is greater than the coherence length of the signal light input to a single delay amplification unit 140(j). When the signal laser passes through the second passive delay fiber 142(j), a differentiated time-domain delay is applied. The length difference determines the time-domain resolution of the sub-pulse shaping. At the same time, this optical path difference design ensures that the N pulses only have intensity superposition after being bundled by the N×1 fiber combiner 147, without interference.

[0030] In a preferred embodiment, the optical path difference between adjacent delay amplification units 140(j) is smaller than the optical path difference between adjacent delay amplification branches 101(i), thereby forming a two-stage delay architecture with large intervals between branches forming pulse train timing and small intervals within units completing single-pulse envelope shaping. At the same time, the fiber specifications and lengths of the gain fiber 143(j) configured in each delay amplification unit 140(j) are the same, ensuring that the basic gain of each unit is consistent. Gain differences can be achieved by adjusting the pump current, simplifying the envelope calibration process.

[0031] In this embodiment of the invention, all optical elements of the pulse train time-domain envelope synthesis system 100 adopt polarization-maintaining fiber and polarization-maintaining device. The broadband seed pulse laser is linearly polarized light, which is transmitted along the fast axis or slow axis of the polarization-maintaining fiber. This can effectively suppress the influence of polarization fluctuations on the pulse amplitude and envelope shape, and improve the stability and consistency of the system output.

[0032] The pulse train time-domain envelope synthesis system 100 provided in this embodiment of the invention adopts a two-stage gain control mechanism combining pre-calibration and electronic control, and realizes flexible control of the time-domain envelope according to the hierarchical logic of "single pulse shaping - pulse train synthesis": The first stage is single-path sub-pulse time-domain envelope shaping: multiple sets of pump power combination parameters are pre-calibrated through experiments. Each set of parameters corresponds to the driving current ratio of N semiconductor pump sources 145(j) in the single-path sub-pulse amplification and shaping unit 14(i), respectively matching preset sub-pulse shapes such as flat-top waveform, ramp waveform, reverse ramp waveform, double-peak waveform, and multi-step waveform. All calibrated parameter sets are pre-stored in the electronic control module 146. When the target sub-pulse waveform is selected during operation, the electronic control module 146 can output the matching driving current to the corresponding semiconductor pump sources 145(j). By independently adjusting the gain of each delay amplification unit 140(j), the N pulses with differentiated delays are made to complete the incoherent intensity superposition, and the shaped sub-pulse with the target time-domain envelope is output.

[0033] The second stage is the overall time-domain envelope synthesis of the pulse train: Based on the adjustable envelope of a single sub-pulse, multiple sets of overall pump power combination parameters between the M sub-pulse amplification and shaping units 14(i) are further calibrated. Each set of overall parameters corresponds to preset pulse train envelope shapes such as flat-top pulse train, exponentially decaying pulse train, ramp pulse train, anti-ramp pulse train, multi-peak pulse train, and multi-step pulse train. The above-mentioned overall parameter sets are also pre-stored in the electronic control module 146. When the target pulse train envelope is selected during operation, the electronic control module can synchronously adjust the pump drive current of the M branches, so that the shaping sub-pulses output by each branch are sequentially bundled and superimposed according to the predetermined time-domain delay order, and finally form the pulse train of the target envelope in the time domain. The entire envelope switching process can be completed online only by adjusting the electrical parameters, without the need to replace any optical components.

[0034] The technical solution of the present invention will now be described in conjunction with specific embodiments.

[0035] Example 1 (Four-sub-pulse train synthesis system with M=4 and N=4): Please see Figure 1 and Figure 2 Example 1 provides a four-sub-pulse train synthesis system, the specific parameters of its main optical components are as follows: The broadband pulse seed source 11 has a center wavelength of 1064 nm, an output spectrum 3dB bandwidth of approximately 20 nm, an output pulse repetition frequency of 140 kHz, a pulse width of 15 ns, and an average power of approximately 50 mW.

[0036] The 1×4 fiber beam splitter divides the seed pulse into four paths with equal power, which are connected to the first passive delay fiber 13(1), the first passive delay fiber 13(2), the first passive delay fiber 13(3), and the first passive delay fiber 13(4), respectively. The lengths of the four fiber segments are 0m, 30m, 60m, and 90m from top to bottom according to the arrangement direction, and the corresponding time domain delays are 0ns, 150ns, 300ns, and 450ns, respectively. The time delay difference between two adjacent sub-pulses is about 150ns, which serves as the time interval between each sub-pulse in the synthesized pulse train. The four pulse lasers after beam splitting are input to the four corresponding sub-pulse amplification and shaping units 14(i).

[0037] Within each subpulse amplification and shaping unit 14(i), a 1×4 fiber beam splitter divides the input subpulse signal laser into four equal-power paths, which are respectively connected to the second passive delay fiber 142(1), the second passive delay fiber 142(2), the second passive delay fiber 142(3), and the second passive delay fiber 142(4). The lengths of the four fiber segments from top to bottom are 3m, 3.5m, 4m, and 4.5m, respectively, and the corresponding time-domain delays are 15ns, 17.5ns, 20ns, and 22.5ns, respectively. The time delay difference between two adjacent paths is approximately 2.5ns, which serves as the time resolution for subpulse time-domain amplification and shaping.

[0038] Each of the four delay branches is equipped with a gain fiber 143(j), which is a double-clad ytterbium-doped fiber with a core / inner cladding diameter of 10 / 130μm and a length of 3m. The pump light cladding absorption coefficient is approximately 1.8dB / m@915nm. Each branch is equipped with a semiconductor pump source 145(j), which is a semiconductor laser with a center wavelength of 915nm and a maximum output power of 10W. Each branch is also equipped with a pump signal combiner 144(j), which is a (1+1)×1 side pump signal combiner.

[0039] The 4×1 fiber combiner combines the four delayed and amplified pulsed laser beams and outputs a single sub-pulse after amplification and shaping. The electrical control module 146 of the single sub-pulse amplification and shaping unit 14(i) has 4 independently adjustable constant current drive channels. The four electrical control modules 146 of the whole system have a total of 16 drive channels, which can independently drive and control the semiconductor pump source 145(j) of each branch.

[0040] Specifically, in this embodiment 1, the driving current parameters of each semiconductor pump source 145(j) corresponding to three typical sub-pulse waveforms are shown in Table 1 below: Table 1

[0041] Based on the flat-topped sub-pulse waveform, the pump current parameters of the 4-channel sub-pulse amplification and shaping unit 14(i) corresponding to the envelopes of the three typical pulse trains are shown in Table 2: Table 2

[0042] Specifically, the working principle of Example 1 is based on the incoherent intensity superposition of broadband pulses and a two-stage independent gain control mechanism. The seed pulse output by the broadband pulse seed source has a short coherence length, so that the optical path difference between each branch after two-stage beam splitting is much greater than the coherence length of the signal light. When the pulses are combined, only intensity superposition occurs without interference fluctuations. The first-stage delay amplification branch 101(i) splits the single pulse into M sub-pulses arranged sequentially in the time domain through differential optical path, forming the basic timing sequence of the pulse train. The second-stage delay amplification unit 140(j) further splits the single sub-pulse into multiple subdivided pulses with micro-scale small-domain intervals, forming the shaping resolution of the sub-pulses. By independently adjusting the driving current of each semiconductor pump source 145(j) through the electronic control module 146, the pulse energy at each time domain position can be precisely controlled. After two-stage beam combining, the pulse train laser output with flexible control of both the sub-pulse shape and the overall envelope of the pulse train is finally achieved.

[0043] The core of this invention lies in combining a 1×M×N beam splitting-multi-path delay structure with independent pump gain control for each path, forming a pulse train synthesis system with two-dimensional "time-domain-power" regulation. The original seed single pulse is expanded into a series of sub-pulse sequences in the time domain after being branched by unequal-length delays. Each sub-pulse is then shaped and amplified by a 1×N beam splitting-multi-path delay amplification structure. The shape of the sub-pulse is controlled by the driving current of the semiconductor pump source 145(j) of each delay amplification unit 140(j), thereby enabling the direct synthesis of complex pulse train envelopes with arbitrary amplitude distributions in the time domain as needed. Furthermore, the time-domain envelope of each sub-pulse within the pulse train is adjustable without the need for any electro-optic or acousto-optic modulators. Simultaneously, by independently controlling the pump power of each path, the gain of each signal laser in the M×N delayed pulses can be precisely set. Ultimately, pulse train outputs with various complex time-domain envelopes and adjustable sub-pulse shapes can be achieved as needed.

[0044] In summary, unlike existing technical solutions, this invention integrates both time-domain separation and precise quantitative energy control within an all-fiber structure. The gain of each sub-pulse is completely independent, and the pulse shape is adjustable, with instantaneous switching via electronic control parameters. This provides a novel path for realizing a fully electronically controlled, modulation-free programmable pulse train laser source, offering the following specific technical advantages: (1) The flexibility of pulse train envelope is greatly improved: By changing the pump drive current value of each channel, the present invention can realize the online switching of different envelopes such as flat-top pulse train, exponential decay pulse train, ramp pulse train, multi-peak pulse train, and step pulse train, without changing the system hardware throughout the process. (2) The shape of each sub-pulse in the pulse train is adjustable and the number is expandable: By changing the value of each pump drive current, the present invention can realize the output of various complex multi-step envelope sub-pulses. Relying on the cascaded structure of multi-level beam splitting and delay, the number of sub-pulses in the pulse train can be expanded many times to adapt to the pulse train length requirements of different processes. (3) High industrial operation stability: The time domain delay of each path in this invention is determined by the fixed fiber length, with zero drift. Combined with the full polarization-maintaining fiber scheme, it can ensure long-term stability of polarization state. (4) Controllable system cost: The present invention is based on standard optical fiber devices and semiconductor pump sources, and does not require additional devices such as acousto-optic or electro-optic modulators.

[0045] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are 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 within the scope of protection of the present invention.

Claims

1. A pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control, characterized in that, It includes a broadband pulse seed source, a 1×M fiber beam splitter, M parallel delay amplification branches with different optical path lengths between branches, and an M×1 fiber combiner, where M≥3 and is a positive integer. The input end of the 1×M fiber beam splitter is connected to the broadband pulse seed source, and the M output ends are respectively connected to the M delay amplification branches; the output ends of the M delay amplification branches are respectively connected to the M input ends of the M×1 fiber beam combiner. Each of the aforementioned delay amplification branches is configured with N parallel delay amplification units and an electronic control module, where N ≥ 3 and is a positive integer. The delay amplification unit is used to sequentially perform differentiated time-domain delay and power amplification processing on the signal light it allocates to output a sub-pulse. The electronic control module is used to independently adjust the gain parameters of each delay amplification unit to achieve independent control of the time-domain envelope of the sub-pulse.

2. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 1, characterized in that, The broadband pulse seed source outputs a broadband seed pulse laser with a spectral width greater than 10 nm, and its output pigtail is connected to the input pigtail of the 1×M fiber beam splitter; the 1×M fiber beam splitter receives the broadband seed pulse laser, and outputs M-path sub-pulse lasers after evenly splitting its power.

3. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 2, characterized in that, Each of the aforementioned delay amplification branches includes a first passive delay fiber and a sub-pulse amplification and shaping unit that are optically connected sequentially along the signal transmission direction. The first passive delay fiber is fused to one output end of the 1×M fiber splitter, and the output end of the sub-pulse amplification and shaping unit is optically connected to one input end of the M×1 fiber combiner.

4. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 3, characterized in that, The lengths of the first passive delay fibers configured in each of the delay amplification branches are not equal, and their lengths increase from top to bottom in an arithmetic sequence along the arrangement direction of the delay amplification branches; the optical path difference formed between two adjacent delay amplification branches is greater than the coherence length of the sub-pulse laser.

5. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 3, characterized in that, Each of the sub-pulse amplification and shaping units includes a 1×N fiber beam splitter, N channels of the delay amplification unit, an N×1 fiber beam combiner, and the electrical control module. The input end of the 1×N fiber beam splitter is fused to the first passive delay fiber to split the single sub-pulse laser into N outputs of equal power. The N outputs of the 1×N fiber beam splitter are connected one-to-one with the inputs of the N delay amplification units, and the outputs of each delay amplification unit are connected one-to-one with the N inputs of the N×1 fiber combiner. The electrical control module is electrically connected to the semiconductor pump source in each delay amplification unit, and the gain of each delay amplification unit is independently controlled by adjusting the pump drive current.

6. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 5, characterized in that, Each of the delay amplification units includes a second passive delay fiber, a gain fiber, a pump signal combiner, and the semiconductor pump source; In this configuration, one end of the second passive delay fiber is fused to one output end of the 1×N fiber splitter, and the other end is fused to the first end of the gain fiber; the signal input end of the pump signal combiner is fused to the second end of the gain fiber, the pump end is connected to the semiconductor pump source, and the output end is connected to one input end of the N×1 fiber combiner.

7. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 6, characterized in that, The lengths of the second passive delay fibers configured in each of the delay amplification units are not equal, and their lengths increase in an arithmetic sequence from top to bottom along the arrangement direction of the delay amplification units; the optical path difference formed by two adjacent delay amplification units is greater than the coherence length of the signal light input to a single delay amplification unit.

8. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 7, characterized in that, The optical path difference between adjacent delay amplification units is less than the optical path difference between adjacent delay amplification branches.

9. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 6, characterized in that, The gain fiber configured in each of the aforementioned delay amplification units has the same fiber specifications and length.

10. The pulse train time-domain envelope synthesis system with multi-channel delay amplification and independent gain control according to claim 2, characterized in that, All optical elements of the pulse train time-domain envelope synthesis system are polarization-maintaining fibers and devices; the broadband seed pulse laser is linearly polarized light, which propagates along the fast or slow axis of the polarization-maintaining fiber.

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