Laser light source system

Abstract

The application provides a laser light source system. The laser light source system comprises a single-pulse seed source, a pulse selector and a repetition frequency multiplier. The output end of the single-pulse 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 burst mode. The single-pulse seed source is used for outputting mode-locked pulses. The pulse selector is used for chopping the mode-locked pulses, adjusting the envelope shape and the repetition frequency. The repetition frequency multiplier is used for adjusting the number of sub-pulses in the envelope and the time interval of adjacent sub-pulses. The application adjusts the envelope repetition frequency and shape, the sub-pulse repetition frequency and the number of sub-pulses of the pulse burst mode laser through the pulse selector and the repetition frequency multiplier, breaks through the limitation of the pulse repetition frequency, and can accurately generate the pulse burst mode laser meeting the requirements.

Description

Technical Field

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

[0002] Pulse burst mode consists of a high-repetition-rate pulse envelope followed by adjacent pulses at lower repetition rates. This mode exhibits high peak power and low average power, and has particular applications in flow measurement, pulsed laser deposition, and combustion diagnostics. Due to its flexible and adjustable parameters, including the number of sub-pulses and repetition rate, envelope shape and repetition rate, and operating wavelength, pulse burst mode is widely used in optical communications, industrial processing, medical treatment, and scientific research.

[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] An embodiment of the present invention provides a laser light source system to solve the problem in the prior art of limited repetition frequency of sub-pulses when a pulse picker 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 laser pulses in a burst mode;

[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 multiplying unit connected in sequence; the input end of the first pulse multiplying unit forms the input end of the repetition rate multiplier, and the output end of the last pulse multiplying unit forms the output end of the repetition rate multiplier;

[0011] The pulse multiplication unit includes: 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 the 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.

[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 the two optical fibers in the pulse multiplication unit is calculated as follows:

[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, the first optical fiber couplers are 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-state laser, or a gas laser.

[0025] An 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 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. 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

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

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

[0029] Figure 3 The present invention provides a spectrum diagram, a pulse sequence, a spectrum diagram and an autocorrelation trace of a mode-locked pulse;

[0030] Figure 4 1 is a schematic structural diagram of a repetition rate multiplier provided by an embodiment of the present invention;

[0031] Figure 5 This 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 is a pulse sequence diagram corresponding to different frequency division coefficients of the acousto-optic modulator provided by an embodiment of the present invention;

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

[0035] In order to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0036] The terms "comprising" and other any variations thereof in the specification and in the claims and the above-mentioned accompanying drawings mean "including but not limited to", and are intended to cover inclusive not exclusive containing, and are not limited to the examples listed in the text. In addition, the terms "first" and "second" and the like are used to distinguish different objects, rather than to describe a specific order.

[0037] The implementation of the present application will be described in detail below with reference to the specific accompanying drawings:

[0038] Figure 1 A structural schematic diagram of a laser light source system is provided for the embodiments of the present application. Referring to 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 laser pulses in burst mode.

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

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

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

[0043] In the embodiments of the present application, the single-pulse seed source 1 outputs mode-locked pulses, on the basis of which the pulse selector 2 adjusts the envelope shape and the frequency, and then the repetition rate multiplier 3 adjusts the repetition frequency and the number of sub-pulses within the envelope, so that the limitation of the pulse repetition frequency can be broken through, and the pulse burst mode laser meeting the application requirements can be accurately generated.

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

[0045] Further, in a possible implementation, the single-pulse seed source 1 can 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 can 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 fully 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 uses the principle of nonlinear polarization rotation to achieve mode locking, thereby obtaining an ultrafast stable dissipative soliton single pulse (mode-locked pulse) transmitted in the ytterbium-doped optical fiber 13 .

[0051] For example, 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; the spectrum diagram shows that its 3-dB spectral width is 6.637 nm, with steep edges, indicating a dissipative soliton; the pulse sequence shows that it is a dissipative soliton single pulse; the spectrum diagram shows that its basic repetition frequency is 24.77 MHz, and the signal-to-noise ratio is 65.21 dB, indicating a stable dissipative soliton single pulse; at the same time, the autocorrelation trace also shows that its pulse width is 2.81 ps, which is an ultrafast stable seed source that meets the application requirements of the embodiments of the present invention.

[0053] In one possible implementation, reference Figure 4 The repetition rate multiplier 3 comprises at least one pulse multiplying unit 31 connected in sequence; the input end of the first pulse multiplying unit 31 forms the input end of the repetition rate multiplier 3, and the output end of the last pulse multiplying 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 the two output ends of the first first fiber coupler 311 are respectively connected to the 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 fiber couplers. The first first fiber coupler 311 splits the pulse signal (pulse 1) into two, and the two signals are respectively transmitted through two optical fibers 313 to the second first fiber coupler 312 and synthesized into one signal. Figure 5 Since the lengths of the two optical fibers are different and there is a time delay, 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 4 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, 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 interval between each pulse, 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 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. 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 two sub-pulses are required, the first pulse multiplication unit 31 outputs them; when four sub-pulses are required, the second pulse multiplication unit 31 outputs them; and when eight sub-pulses are required, the third pulse multiplication unit 31 outputs them.

[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] The number of pulse multiplication units 31 in the repetition frequency multiplier 3 and the difference of the optical fibers in each pulse multiplication unit can be determined according to the number of sub-pulses and the time interval of the sub-pulses, and the number of sub-pulses and the repetition frequency of the pulse burst mode can be adjusted by changing the number of pulse multiplication units 31 in the repetition frequency multiplier 3 and the difference of the optical fibers in each pulse multiplication unit.

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

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

[0076] Meanwhile, since the dissipative soliton is used as the seed source in the embodiment of the application, the coupling ratio of the first fiber coupler can be prevented from fluctuating too much, the stability and accuracy of the coupling ratio of the first fiber coupler are improved, and the adaptability of the first fiber coupler to the all-normal-dispersion ytterbium-doped fiber laser is increased.

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

[0078] For example, the pulse selector 2 can be an acousto-optic modulator, which includes an electrically controlled selector and can be connected to the upper computer, so that the frequency division coefficient, pulse train, delay and gate width and other parameters of the acousto-optic modulator can be changed by the upper computer.

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

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

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

[0082] In a possible implementation, the first fiber couplers can be connected by fiber fusion technology.

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

[0084] Corresponding to the above embodiments, 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 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 they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. 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 various 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 laser pulses 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; The repetition rate multiplier comprises at least one pulse multiplying unit connected in sequence; the input end of the first pulse multiplying unit forms the input end of the repetition rate multiplier, and the output end of the last pulse multiplying unit forms the output end of the repetition rate multiplier; The pulse multiplication unit includes: 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 via 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; The calculation formula for the number of pulse multiplication units in the repetition rate multiplier is: in, is the number of sub-pulses in the envelope, is the number of pulse multiplication units in the repetition rate multiplier, ; The calculation formula for the length difference between the two optical fibers in the pulse multiplication unit is: in, For the The length difference between the two optical fibers in a pulse multiplication unit, , is the number of pulse multiplication units in the repetition rate multiplier; is the refractive index of the optical fiber, is the time interval between adjacent sub-pulses, is the speed of light in a vacuum.

2. The laser light source system according to claim 1, wherein: The time interval between adjacent sub-pulses is greater than the single pulse duration of the mode-locked pulse.

3. The laser light source system according to claim 1, wherein: The coupling ratio of the first optical fiber coupler is 50:

50.

4. The laser light source system according to claim 1, wherein: The first optical fiber couplers are connected by optical fiber fusion splicing technology.

5. The laser light source system according to any one of claims 1 to 4, wherein: The pulse selector is an acousto-optic modulator, an electro-optic modulator, a phase modulator or an intensity modulator.

6. The laser light source system according to any one of claims 1 to 4, wherein: The single pulse seed source is an ultrashort pulse laser.

7. The laser light source system according to claim 6, wherein: The single pulse seed source is a fiber laser, a solid laser or a gas laser.

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