Laser light source system

Abstract

The invention provides a laser light source system. The laser light source system comprises a monopulse seed source, a pulse selector and a repetition frequency multiplier, the output end of the monopulse seed source is connected with the input end of the pulse selector, the output end of the pulse selector is connected with the input end of the repetition frequency multiplier, and the output end of the repetition frequency multiplier is used for outputting laser pulses in an explosion mode; the monopulse seed source is used for outputting mode-locked pulses; the pulse selector is used for chopping mode-locked pulses and adjusting an envelope shape and repetition frequency; the repetition frequency multiplier is used for adjusting the number of sub-pulses in the envelope and the time interval between adjacent sub-pulses. According to the invention, the envelope repetition frequency, the shape, the sub-pulse repetition frequency and the number of the pulse burst mode laser are adjusted through the pulse selector and the repetition frequency multiplier, the limitation of the pulse repetition frequency is broken through, and the pulse burst mode laser meeting the requirements can be accurately generated.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to a laser light source system. Background Art

[0002] The pulse burst mode is composed of a single pulse with a high repetition rate and an adjacent pulse envelope with a low repetition rate. Therefore, it has the characteristics of high peak power and low average power, and has special applications in flow measurement, pulsed laser deposition, combustion diagnosis, etc. Since the pulse burst mode has the advantages of flexible and adjustable parameters such as the number of sub-pulses and repetition frequency, envelope shape and repetition frequency, and working wavelength, it is widely used in optical communications, industrial processing, medical treatment, scientific research, etc.

[0003] In the prior art, a pulse picker is usually used to chop a pulse sequence to obtain a pulse burst mode. However, due to the nature of the pulse picker's frequency reduction control, the repetition frequency of the sub-pulses is limited by the repetition frequency of the pulse source. Summary of the invention

[0004] The embodiment of the present invention provides a laser light source system to solve the problem in the prior art that the repetition frequency of sub-pulses is limited when a pulse selector is used to generate a pulse burst mode laser.

[0005] In a first aspect, an embodiment of the present invention provides a laser light source system, comprising: a single pulse seed source, a pulse selector and a repetition rate multiplier;

[0006] The output end of the single pulse seed source is connected to the input end of the pulse selector, the output end of the pulse selector is connected to the input end of the repetition rate multiplier, and the output end of the repetition rate multiplier is used to output a burst mode laser pulse;

[0007] The single pulse seed source is used to output the mode-locked pulse;

[0008] The pulse picker is used to chop the mode-locked pulse and adjust the envelope shape and repetition frequency;

[0009] The repetition rate multiplier is used to adjust the number of sub-pulses in the envelope and the time interval between adjacent sub-pulses.

[0010] Optionally, the repetition rate multiplier comprises at least one pulse multiplication unit connected in sequence; the input end of the first pulse multiplication unit forms the input end of the repetition rate multiplier, and the output end of the last pulse multiplication unit forms the output end of the repetition rate multiplier;

[0011] The pulse multiplication unit comprises: two first optical fiber couplers;

[0012] An input end of the first first fiber coupler forms the input end of the pulse multiplication unit, and two output ends of the first first fiber coupler are respectively connected to two input ends of the second first fiber coupler through two optical fibers; an output end of the second first fiber coupler forms the output end of the pulse multiplication unit; wherein the lengths of the two optical fibers are different.

[0013] Optionally, the calculation formula for the number of pulse multiplication units in the repetition rate multiplier is:

[0014] m=2 N

[0015] Wherein, m is the number of sub-pulses in the envelope, N is the number of pulse multiplication units in the repetition rate multiplier, N = 1, 2, ...

[0016] Optionally, the length difference between two optical fibers in the pulse multiplication unit is calculated as:

[0017]

[0018] Among them, L i is the length difference between the two optical fibers in the i-th pulse multiplication unit, i=1, 2, ..., N-1, N is the number of pulse multiplication units in the repetition rate multiplier; n is the refractive index of the optical fiber, and T0 is the time interval between adjacent sub-pulses.

[0019] Optionally, the time interval between adjacent sub-pulses is greater than the single pulse duration of the mode-locked pulse.

[0020] Optionally, the coupling ratio of the first optical fiber coupler is 50:50.

[0021] Optionally, each first optical fiber coupler is connected by optical fiber fusion splicing technology.

[0022] Optionally, the pulse selector is an acousto-optic modulator, an electro-optic modulator, a phase modulator or an intensity modulator.

[0023] Optionally, the single pulse seed source is an ultrashort pulse laser.

[0024] Optionally, the single pulse seed source is a fiber laser, a solid laser or a gas laser.

[0025] The embodiment of the present invention provides a laser light source system. The above-mentioned laser light source system includes: a single pulse seed source, a pulse selector and a repetition rate multiplier; the output end of the single pulse seed source is connected to the input end of the pulse selector, the output end of the pulse selector is connected to the input end of the repetition rate multiplier, and the output end of the repetition rate multiplier is used to output a burst mode laser pulse; the single pulse seed source is used to output a mode-locked pulse; the pulse selector is used to chop the mode-locked pulse, adjust the envelope shape and repetition frequency; the repetition rate multiplier is used to adjust the number of sub-pulses in the envelope and the time interval between adjacent sub-pulses. In the embodiment of the present invention, the envelope shape and frequency in the pulse burst mode laser are adjusted by the pulse selector, and the repetition frequency and number of sub-pulses in the envelope are adjusted by the repetition rate multiplier, which can break through the limitation of the pulse repetition frequency and accurately generate a pulse burst mode laser that meets the application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 is a structural schematic diagram of a laser light source system provided by an embodiment of the present invention;

[0028] Figure 2 is a schematic structural diagram of a single pulse seed source provided by an embodiment of the present invention;

[0029] Figure 3 It is a spectrum diagram, pulse sequence, spectrum diagram and autocorrelation trace of a mode-locked pulse provided by an embodiment of the present invention;

[0030] Figure 4 is a structural schematic diagram of a repetition rate multiplier provided by an embodiment of the present invention;

[0031] Figure 5 is an output sequence diagram of a pulse multiplication unit provided by an embodiment of the present invention;

[0032] Figure 6 A pulse burst mode sequence diagram provided by an embodiment of the present invention;

[0033] Figure 7 1. The pulse sequence diagrams corresponding to different frequency division coefficients of the acousto-optic modulator provided by the embodiment of the present invention;

[0034] Figure 8 1 is a pulse burst mode sequence diagram of two different laser light source systems provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0036] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0037] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0038] Figure 1 A schematic diagram of the structure of a laser light source system provided by an embodiment of the present invention. Figure 1 , the laser light source system comprises: a single pulse seed source 1, a pulse selector 2 and a repetition rate multiplier 3;

[0039] The output end of the single pulse seed source 1 is connected to the input end of the pulse selector 2, the output end of the pulse selector 2 is connected to the input end of the repetition rate multiplier 3, and the output end of the repetition rate multiplier 3 is used to output a laser pulse in a burst mode;

[0040] The single pulse seed source 1 is used to output a mode-locked pulse;

[0041] The pulse selector 2 is used to chop the mode-locked pulse and adjust the envelope shape and repetition frequency;

[0042] The repetition rate multiplier 3 is used to adjust the number of sub-pulses in the envelope and the time interval between adjacent sub-pulses.

[0043] In the embodiment of the present invention, a mode-locked pulse is outputted through a single pulse seed source 1, and on this basis, the envelope shape and frequency are adjusted through a pulse selector 2, and then the repetition frequency and number of sub-pulses in the envelope are adjusted through a repetition rate multiplier 3, which can break through the limitation of the pulse repetition frequency and accurately generate a pulse burst mode laser that meets the application requirements.

[0044] In a possible implementation, the single pulse seed source 1 may be an ultrashort pulse laser.

[0045] Furthermore, in a possible implementation, the single-pulse seed source 1 may be a fiber laser, a solid-state laser or a gas laser.

[0046] For example, if the single-pulse seed source 1 is a fiber laser, the single-pulse seed source 1 may be a net positive fiber laser, an all-positive fiber laser, or a net negative fiber laser.

[0047] For another example, if the single pulse seed source 1 is a fiber laser, the single pulse seed source 1 may also be a gain-doped fiber laser such as an ytterbium-doped fiber laser, an erbium-doped fiber laser or a thulium-doped fiber laser.

[0048] More specifically, the single pulse seed source 1 may be a full positive dispersion ytterbium-doped fiber laser.

[0049] Specifically, the single pulse seed source 1 may include: a laser diode 11, a wavelength division multiplexer 12, an ytterbium-doped optical fiber 13, a second optical fiber coupler 14, a first squeezed polarization controller 15, a polarization-dependent isolator 16, a second squeezed polarization controller 17 and a bandpass filter 18; for specific connection methods, see Figure 2 The various components can also be arranged on the optical plate 19.

[0050] The single pulse seed source 1 provided in the embodiment of the present invention realizes mode locking by using the principle of nonlinear polarization rotation, thereby obtaining an ultrafast stable dissipative soliton single pulse (mode-locked pulse) transmitted in the ytterbium-doped optical fiber 13 .

[0051] Exemplarily, the laser diode 11 may be a 976 nm laser diode, the length of the ytterbium-doped optical fiber 13 may be 0.5 m, and the second optical fiber coupler 14 may be a 50:50 optical fiber coupler.

[0052] Figure 3 The spectrum diagram, pulse sequence, spectrum diagram and autocorrelation trace of the mode-locked pulse output when the pump power is 146 mW are shown; from the spectrum diagram, it can be seen that its 3-dB spectrum width is 6.637 nm, with steep edges, and is a dissipative soliton; from the pulse sequence, it can be seen that it is a dissipative soliton single pulse; from the spectrum diagram, it can be seen that its basic repetition frequency is 24.77 MHz, and the signal-to-noise ratio is 65.21 dB, which is a stable dissipative soliton single pulse; at the same time, it can also be seen from the autocorrelation trace that its pulse width is 2.81 ps, which is an ultrafast stable seed source that meets the application requirements of the embodiment of the present invention.

[0053] In one possible implementation, reference Figure 4 The repetition rate multiplier 3 comprises at least one pulse multiplication unit 31 connected to each other in sequence; the input end of the first pulse multiplication unit 31 forms the input end of the repetition rate multiplier 3, and the output end of the last pulse multiplication unit 31 forms the output end of the repetition rate multiplier 3;

[0054] The pulse multiplication unit 31 may include: two first fiber couplers (311 and 312);

[0055] An input end of the first first fiber coupler 311 forms the input end of the pulse multiplication unit 31, and two output ends of the first first fiber coupler 311 are respectively connected to two input ends of the second first fiber coupler 312 through two optical fibers 313; an output end of the second first fiber coupler 312 forms the output end of the pulse multiplication unit 31; wherein the lengths of the two optical fibers 313 are different.

[0056] In the embodiment of the present invention, reference Figure 4 The pulse multiplication unit 31 includes two first optical fiber couplers. The first first optical fiber coupler 311 divides the pulse signal (pulse No. 1) into two, and the two signals are respectively transmitted through two optical fibers 313 to the second first optical fiber coupler 312 and synthesized into one signal. Figure 5 ,Since the lengths of the two optical fibers are different, there is a delay, so one pulse (pulse 1) in the original signal is delayed and synthesized into two pulses (pulse 1 and pulse 2);

[0057] The delay between two pulses is Wherein, L1 is the length difference between the two optical fibers in the first pulse multiplication unit 31; and n is the refractive index of the optical fiber.

[0058] Similarly, if a two-stage pulse multiplication unit 31 is provided, refer to Figure 5 , then the two pulses become four pulses (pulse 1 and pulse 2 are delayed to form pulse 3 and pulse 4 respectively); the time interval between the two groups (2 pulses) is Wherein, L2 is the length difference between the two optical fibers in the second pulse multiplication unit 31;

[0059] Based on the above analysis, since the pulse multiplication unit 31 multiplies by 2 times each time, in a possible implementation manner, the calculation formula for the number of pulse multiplication units 31 in the repetition rate multiplier 3 can be:

[0060] m=2 N

[0061] Wherein, m is the number of sub-pulses in the envelope, N is the number of pulse multiplication units 31 in the repetition rate multiplier 3, N = 1, 2, ... .

[0062] In a possible implementation manner, the calculation formula for the length difference between the two optical fibers in the pulse multiplication unit 31 may be:

[0063]

[0064] Among them, L iis the length difference between the two optical fibers in the i-th pulse multiplication unit 31, i=1, 2, ..., N-1, N is the number of pulse multiplication units 31 in the repetition rate multiplier 3; n is the refractive index of the optical fiber, and T0 is the time interval between adjacent sub-pulses.

[0065] Based on the above analysis, we can see that Figure 5 , ignoring the pulse width, the time interval between pulse 1 and pulse 2 is T2, and the time interval between pulse 1 and pulse 2 is T1. To ensure the consistency of the time intervals between pulses, T2 should be half of T1.

[0066] And so on.

[0067] Based on the above analysis, but

[0068] From this we can get,

[0069] The delay of the last pulse multiplication unit 31 determines the time interval between each sub-pulse. The time interval between adjacent sub-pulses is defined as T0. That is to say

[0070] For example, Figure 4 The repetition rate multiplier 3 in the embodiment includes three pulse multiplication units 31, and the number of sub-pulses outputted from the output end of each pulse multiplication unit 31 is 2, 4, and 8 respectively. In order to improve the applicability of the repetition rate multiplier 3, the second output end of the pulse multiplication unit 31 can be led out (314). For example, when 2 sub-pulses are needed, the first pulse multiplication unit 31 outputs; when 4 sub-pulses are needed, the second pulse multiplication unit 31 outputs; when 8 sub-pulses are needed, the third pulse multiplication unit 31 outputs.

[0071] The difference between the two optical fibers in each pulse multiplication unit 31 is 2.4m, 1.2m, and 0.6m, respectively, and the delay is 12ns, 6ns, and 3ns, respectively. Figure 6 .

[0072] The differences between the two optical fibers in each pulse multiplication unit 31 are 0.44 m, 0.22 m, and 0.11 m, respectively, so the delays are 2.2 ns, 1.1 ns, and 0.55 ns, respectively.

[0073] In the embodiment of the present invention, the number of pulse multiplying units 31 in the repetition rate multiplier 3 and the difference in optical fibers in each pulse multiplying unit can be determined according to the number of sub-pulses and the time intervals of the sub-pulses. The number of sub-pulses and the repetition frequency of the pulse burst mode can be adjusted by changing the number of pulse multiplying units 31 in the repetition rate multiplier 3 and the difference in optical fibers in each pulse multiplying unit.

[0074] In a possible implementation manner, the coupling ratio of the first optical fiber coupler may be 50:50.

[0075] The present invention limits the coupling ratio of the first optical fiber coupler to 50:50, ensuring uniform light splitting and uniform amplitude distribution of the pulse burst mode.

[0076] At the same time, since the embodiment of the present invention adopts dissipative solitons as the seed source, it is possible to avoid excessive fluctuations in the coupling ratio of the first optical fiber coupler, improve the stability and accuracy of the coupling ratio of the first optical fiber coupler, and increase the compatibility of the first optical fiber coupler with the full-positive dispersion ytterbium-doped fiber laser.

[0077] In a possible implementation, the pulse selector 2 may be an acousto-optic modulator, an electro-optic modulator, a phase modulator or an intensity modulator.

[0078] For example, the pulse selector 2 may be an acousto-optic modulator, which includes an electronically controlled selector that can be connected to a host computer to change parameters such as the frequency division coefficient, pulse train, delay, and gate width of the acousto-optic modulator through the host computer.

[0079] Figure 7 The figure shows the pulse sequence diagram when the pulse selector 2 is an acousto-optic modulator, and the frequency division coefficients are 2, 3, 4, 5, 6 and 7 respectively. Figure 7 It can be seen that the chopping effect is very good, the amplitude distribution is uniform, and the pulse burst mode envelope interval can be adjusted.

[0080] In a possible implementation manner, the time interval between adjacent sub-pulses is greater than a single pulse duration of the mode-locked pulse.

[0081] To ensure that the sub-pulses do not overlap, the time interval between adjacent sub-pulses is greater than the single pulse duration of the mode-locked pulse.

[0082] In a possible implementation manner, each first optical fiber coupler may be connected by using an optical fiber fusion splicing technology.

[0083] The first optical fiber couplers and other components can be connected by using optical fiber fusion splicing technology.

[0084] Corresponding to the above embodiment, Figure 8The pulse burst mode sequence diagrams are shown respectively when the frequency division coefficient is 2 and the first-level optical fiber difference is 44cm, and the pulse burst mode sequence diagrams are shown when the frequency division coefficient is 5 and the first-level optical fiber difference is 2.4m. Figure 8 It can be seen that the envelope and sub-pulse repetition frequency are both precisely adjustable, the amplitude distribution is uniform, and the stability is strong, which greatly improves the practicality of the pulse burst mode.

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser light source system, characterized in that: include: Single pulse seed source, pulse selector and repetition rate multiplier; The output end of the single pulse seed source is connected to the input end of the pulse selector, the output end of the pulse selector is connected to the input end of the repetition rate multiplier, and the output end of the repetition rate multiplier is used to output a laser pulse in a burst mode; The single pulse seed source is used to output a mode-locked pulse; The pulse selector is used to chop the mode-locked pulse and adjust the envelope shape and repetition frequency; The repetition rate multiplier is used to adjust the number of sub-pulses in the envelope and the time interval between adjacent sub-pulses.

2. The laser light source system according to claim 1, characterized in that: The repetition rate multiplier comprises at least one pulse multiplication unit connected in sequence; the input end of the first pulse multiplication unit forms the input end of the repetition rate multiplier, and the output end of the last pulse multiplication unit forms the output end of the repetition rate multiplier; The pulse multiplication unit comprises: two first optical fiber couplers; An input end of the first first fiber coupler forms the input end of the pulse multiplication unit, and two output ends of the first first fiber coupler are respectively connected to two input ends of the second first fiber coupler through two optical fibers; an output end of the second first fiber coupler forms the output end of the pulse multiplication unit; wherein the two optical fibers have different lengths.

3. The laser light source system according to claim 2, characterized in that: The calculation formula for the number of pulse multiplication units in the repetition rate multiplier is: m＝2 N Wherein, m is the number of sub-pulses in the envelope, N is the number of pulse multiplication units in the repetition rate multiplier, N=1, 2, ...

4. The laser light source system according to claim 2, characterized in that: The calculation formula for the length difference of the two optical fibers in the pulse multiplication unit is: Among them, L i is the length difference between the two optical fibers in the i-th pulse multiplication unit, i=1, 2, ..., N-1, N is the number of pulse multiplication units in the repetition rate multiplier; n is the refractive index of the optical fiber, and T0 is the time interval between adjacent sub-pulses.

5. The laser light source system according to claim 4, characterized in that: The time interval between the adjacent sub-pulses is greater than the single pulse duration of the mode-locked pulse.

6. The laser light source system according to claim 2, characterized in that: The coupling ratio of the first optical fiber coupler is 50:

50.

7. The laser light source system according to claim 2, characterized in that: The first optical fiber couplers are connected by optical fiber fusion splicing technology.

8. The laser light source system according to any one of claims 1 to 7, characterized in that: The pulse selector is an acousto-optic modulator, an electro-optic modulator, a phase modulator or an intensity modulator.

9. The laser light source system according to any one of claims 1 to 7, characterized in that: The single pulse seed source is an ultrashort pulse laser.

10. The laser light source system according to claim 9, characterized in that: The single pulse seed source is a fiber laser, a solid laser or a gas laser.

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