阅读说明：本技术 抑制波形畸变的功能模块及方法 (Functional module and method for inhibiting waveform distortion ) 是由 谭小妹 刘赟 李文涛 关珮雯 于 2020-12-10 设计创作，主要内容包括：一种抑制波形畸变的功能模块,其特点在于包括脉冲输入模块、波形畸变抑制模块和脉冲放大模块,本发明通过编辑脉冲上升沿为特定的函数,将上升沿放缓,延长上升沿吸收放大器中反转粒子数的时间,平衡脉冲前沿与后沿的增益,进而改善因增益差引起的脉冲畸变。本发明具有结构简单、功能模块化、集成度高、成本低和操作简单的特点,可有效改善输出脉冲波形畸变。(The invention relates to a functional module for inhibiting waveform distortion, which is characterized by comprising a pulse input module, a waveform distortion inhibiting module and a pulse amplifying module. The invention has the characteristics of simple structure, modular function, high integration level, low cost and simple operation, and can effectively improve the waveform distortion of output pulses.)

1. A functional module for suppressing waveform distortion, comprising:

a pulse input module: used for emitting seed pulse light;

a waveform distortion suppression module: the pulse light source is used for adjusting the rising edge of input seed pulse light and inhibiting waveform distortion;

the pulse amplification module: the laser is used for amplifying the power of the pulse laser and improving the single pulse energy.

2. The functional module for suppressing waveform distortion according to claim 1, comprising the waveform distortion suppressing module (2) including a rising edge function generator (2-1) and a pulse rising edge editor (2-2), wherein an output of the pulse input module (1) is connected to a first input of the pulse rising edge editor (2-2), an output of the rising edge function generator (2-1) is connected to a second input of the pulse rising edge editor (2-2), an output of the pulse rising edge editor (2-2) is connected to an input of the pulse amplifying module (3), and the seed pulse light output by the pulse input module (1) enters the pulse rising edge editor (2-2), under the function effect generated by the rising edge function generator (2-1), after the rising edge editor (2-2) edits the rising edge of the seed pulse light, the pulse amplification module (3) amplifies the power of the pulse laser and improves the single pulse energy.

3. The functional module for suppressing waveform distortion according to claim 2, wherein the function generator (2-1) comprises N time-delay generating switch sets (2-1-1), a signal superimposer (2-1-2) and a low-pass filter (2-1-3), the signal superimposer (2-1-2) superimposes the signals with different time delays generated by the N time-delay generating switch sets (2-1-1), and the noise is filtered by the low-pass filter (2-1-3) and then input to the pulse rising edge editor (2-2) via the second input terminal of the pulse rising edge editor (2-2).

4. The functional module for suppressing waveform distortion as set forth in claim 3, wherein N ≧ 3.

5. The method for suppressing waveform distortion using the functional module for suppressing waveform distortion as claimed in any one of claims 1 to 4, wherein the method comprises the steps of:

presetting a corresponding current value for each group of switch channels, wherein the current value is determined by a resistance value serially connected into the switch group, and the on-off of the switch is controlled by a programmable logic gate chip;

let n be the total number of switch groups, and t be the number of the first switch group₀At a time t_nThe first switch group is disconnected at any time, and a first switch group preset current waveform is generated; the second switch group is at t₁At a time t_nThe current is constantly switched off, and a second switch group preset current waveform is generated; by analogy, the nth switch group is at t_n－1At a time t_nThe n-th switch group is disconnected at the moment to generate a preset current waveform, wherein delta t₁＝t₁-t₀The phase difference of the second switch group relative to the first switch group is called, and the like;

thirdly, superposing the preset current waveform of the first switch group, the preset current waveform of the second switch group, … … and the preset current waveform of the nth switch group by adopting an addition circuit constructed by an operational amplifier, and outputting a superposed waveform;

and fourthly, after low-pass filtering processing is carried out on the superposed waveform, the seed laser is directly driven through current amplification, the closing period of each switch group is adjusted through adjusting the preset current of each switch, and the phase difference of the closing periods among the switch groups is changed to synthesize a plurality of pulse shapes.

Technical Field

The invention relates to a laser technology, in particular to a functional module and a method for inhibiting waveform distortion.

Background

The high-power long-pulse fiber laser has a great application prospect in the fields of 3D scanning, laser marking, atmospheric detection, laser cleaning and the like. In the MOPA technology, low-power laser is used as seed light and is injected into a large-mode-field-diameter optical fiber amplifier, and high-power laser output with the same wavelength is obtained through power amplification. The technology can obtain high-power laser output with flexibly adjustable repetition frequency and pulse width, the laser wavelength, the repetition frequency, the frequency spectrum width and the time domain pulse width of the output are all determined by seed sources, and the task of realizing high power is mainly given to an amplifier, so that the technology is a very effective technical means for obtaining high-power pulses.

However, in the optical fiber amplifier, more inversion population is accumulated before the pulse arrives, the rising edge of the optical pulse firstly enters the gain optical fiber, the upper level population is consumed and the amplification gain is obtained, and the later arriving pulse trailing edge causes the gain obtained by the optical fiber to be reduced because the residual upper level population in the optical fiber is reduced. Therefore, after the square pulse passes through the amplifier, the time domain waveform is distorted due to the existence of the gain difference of the front edge and the back edge, which is shown in the figure 1 and 2 that the amplitude of the front edge of the pulse is high and the amplitude of the back edge part of the pulse is in exponential decay distribution. Moreover, the larger the fiber gain, the larger the distortion; the wider the seed pulse width, the greater the distortion. Due to the fact that the nonlinear threshold of the optical fiber is low, under the same single pulse energy and pulse width, if pulse distortion is large, the amplified pulse width is narrowed, and peak power is too high, so that improvement of the single pulse energy is limited, and application effect and range of laser processing are affected.

In order to solve the above technical problems, the prior art provides an electro-optical modulation based pulse-shaped MOPA fiber laser, which compensates the signal waveform through an electro-optical regulator, and improves the output waveform to increase the single pulse energy of the output laser. However, the electro-optical modulator introduces large loss and is expensive, the high loss causes the optical power of the seed entering the amplifier to be reduced, and if a high-power pulse laser output is to be obtained, a multi-stage preamplifier needs to be added, which increases the complexity of the system structure and reduces the reliability.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a functional module for suppressing waveform distortion. The functional module balances the gains of the front edge and the back edge of the pulse by editing the rising edge of the pulse as a specific function, slowing down the rising edge and prolonging the time for the rising edge to absorb the number of particles reversed in the amplifier, thereby improving the pulse distortion caused by the gain difference.

The technical solution of the invention is as follows:

the utility model provides a function module for restraining waveform distortion, its characterized in that includes pulse input module, waveform distortion suppression module and pulse amplification module, the waveform distortion suppression module include rising edge function generator and pulse rising edge editor, pulse input module output with the first input of the pulse rising edge editor of waveform distortion suppression module link to each other, rising edge function generator's output with the second input of pulse rising edge editor link to each other, the output of pulse rising edge editor with the input of pulse amplification module link to each other, pulse input module output seed pulse light get into the pulse rising edge editor, under the function effect that the rising edge function generator produced, after the rising edge editor edited the rising edge of pulse light, the power of the pulse laser is amplified and the single pulse energy is improved through the pulse amplification module.

The function generator comprises N switch groups for generating time delay, a signal superimposer and a low-pass filter, wherein N is more than or equal to 3, the more the number of switches is, the higher the function precision is, the signal superimposer superimposes signals with different time delay generated by the N switch groups for generating time delay, and then the signals are input into the pulse rising edge editor through the second input end of the pulse rising edge editor after noise is filtered by the low-pass filter.

A functional module for suppressing waveform distortion, comprising a pulse input module: for emitting seed light;

the pulse input module emits seed light with a specific waveform, after the seed light passes through the waveform distortion suppression module, the rising edge of the seed pulse is edited into any target function (including but not limited to a linear function, an exponential function, a step function and the like), and then the pulse amplification module is used for amplifying the power and improving the energy of the pulse laser.

The working principle of the invention is as follows:

the pulse input module emits seed light with a square wave waveform, the seed pulse enters the waveform distortion suppression module, the pulse is modified by a pulse rising edge editor in the module to form a pulse rising edge, and the shape of the rising edge is generated by a function generator. And the pulse after passing through the waveform distortion suppression module is subjected to power amplification and energy improvement through the pulse amplification module. Since the rising edge of the pulse can be edited into any function, if the rising edge is slowed down, the time for the rising edge to absorb the number of particles reversed in the amplifier is prolonged, so that the gains of the leading edge and the trailing edge of the pulse can be balanced, and the pulse distortion caused by the gain difference can be improved.

On the other hand, the invention also provides a method for realizing the suppression of the waveform distortion by adopting the functional module for suppressing the waveform distortion, which comprises the following steps:

presetting a corresponding current value for each group of switch channels, wherein the current value is determined by a resistance value serially connected into the switch group, and the on-off of the switch is controlled by a programmable logic gate chip;

let n be the total number of switch groups, and t be the number of the first switch group₀At a time t_nThe first switch group is disconnected at any time, and a first switch group preset current waveform is generated; the second switch group is at t₁At a time t_nThe current is constantly switched off, and a second switch group preset current waveform is generated; by analogy, the nth switch group is at t_n－1At a time t_nThe n-th switch group is disconnected at the moment to generate a preset current waveform, wherein delta t₁＝t₁-t₀The phase difference of the second switch group relative to the first switch group is called, and the like;

thirdly, superposing the preset current waveform of the first switch group, the preset current waveform of the second switch group, … … and the preset current waveform of the nth switch group by adopting an addition circuit constructed by an operational amplifier, and outputting a superposed waveform;

and fourthly, after low-pass filtering processing is carried out on the superposed waveform, the seed laser is directly driven through current amplification, the closing period of each switch group is adjusted through adjusting the preset current of each switch, and the phase difference of the closing periods among the switch groups is changed to synthesize a plurality of pulse shapes.

The invention has the following technical effects:

(1) the existing market is constructed by a high sampling rate DA, the cost is high, the structure is complex, the structure is simple, the function is modularized, and the integration level is high; low cost, simple operation and reliable operation.

(2) The seed laser is driven by the waveform current, so that the energy injected into the amplification stage is changed exponentially within a pulse width time, the high gain of the amplification stage to the front edge of a signal is effectively inhibited, and the pulse distortion is improved.

Drawings

FIG. 1 is a diagram illustrating an input waveform in the prior art;

FIG. 2 is a diagram illustrating an output waveform in the prior art;

FIG. 3 is a first function generated by the function generator of the present invention;

FIG. 4 is a schematic diagram of an amplified output waveform of a corresponding input waveform of a function of the present invention;

FIG. 5 is a schematic structural diagram of a functional module for suppressing waveform distortion according to the present invention;

FIG. 6 is a schematic diagram of a function generator according to the present invention;

FIG. 7 is a schematic diagram of the relationship between the switch set and the predetermined current according to the present invention;

FIG. 8 is a schematic diagram of a waveform after the switch sets are stacked according to the present invention;

FIG. 9 is a schematic diagram of the output waveform after filtering according to the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples, which should not be construed as limiting the scope of the invention.

Referring to fig. 5 and 6, fig. 5 is a schematic structural diagram of a functional module for suppressing waveform distortion of the present invention, and fig. 6 is a schematic structural diagram of a function generator of the present invention, as can be seen from the drawings, the functional module for suppressing waveform distortion of the present invention includes a pulse input module 1, a waveform distortion suppression module 2 and a pulse amplification module 3, the waveform distortion suppression module 2 includes a rising edge function generator 2-1 and a pulse rising edge editor 2-2, an output end of the pulse input module 1 is connected to a first input end of the pulse rising edge editor 2-2 of the waveform distortion suppression module 2, an output end of the rising edge function generator 2-1 is connected to a second input end of the pulse rising edge editor 2-2, an output end of the pulse rising edge editor 2-2 is connected to an input end of the pulse amplification module 3, the seed pulse light output by the pulse input module 1 enters the pulse rising edge editor 2-2, and under the function effect generated by the rising edge function generator 2-1, after the rising edge of the seed pulse light is edited by the pulse rising edge editor 2-2, the power amplification and single pulse energy of the pulse laser are improved through the pulse amplification module 3.

The function generator 2-1 comprises N switches 2-1-1 for generating time delay, a signal superimposer 2-1-2 and a low-pass filter 2-1-3, wherein N is more than or equal to 3, the more the number of the switches is, the higher the function precision is, the signal superimposer 2-1-2 superimposes signals with different time delay generated by the N switches 2-1-1 for generating time delay, and then the signals are input into the pulse rising edge editor 2-2 through a second input end of the pulse rising edge editor 2-2 after noise is filtered by the low-pass filter 2-1-3.

Examples

As shown in fig. 5, a functional module for suppressing waveform distortion includes a pulse input module 1: for emitting seed light; in this embodiment, the pulse input module 1 includes a semiconductor laser and a driving board thereof;

the waveform distortion suppression module 2: the device is used for adjusting the rising edge of the input pulse so as to inhibit waveform distortion; in the present embodiment, a function generator 2-1 (the function is an exponential function) and a pulse rising edge editor 2-2 are included;

the function generator 2-1 is shown in fig. 6, and includes a "switch bank" 2-1-1 for generating time delay (the number of switch banks N is 7, the higher the number of switches, the higher the function precision), a "signal superimposer" 2-1-2 for superimposing signals with different time delays, and a "low-pass filter" 2-1-3 for filtering noise. The on-off time and current of each switch are set through the switch group, and the rising edge of the pulse can be simulated into different functions by matching with the signal adder and the low-pass filter.

The pulse amplification module 3: the power amplification and single pulse energy promotion are used for pulse laser; in this embodiment, the pulse amplification module 3 includes an isolator, an active fiber (double-clad ytterbium-doped fiber), a pump combiner, and the like.

The method for realizing the suppression of the waveform distortion by using the functional module for suppressing the waveform distortion comprises the following steps:

step 1, as shown in fig. 6, in this embodiment, the number of switch groups is 7, and a corresponding current value is preset for each group of switch channels, and the current value is determined by a resistance value serially connected to the switch group. The on-off of the switch is controlled by a programmable logic gate chip, the working frequency of the chip in the embodiment reaches 500MHz, and the time resolution is 2 ns.

Step 2. As shown in FIG. 7, switch sets 1, t₀At a time t₇The switch is switched off at any time, and a preset current waveform of the switch group 1 is generated;

switch group 2, t₁At a time t₇The current is switched off at any time, and a preset current waveform of the switch group 2 is generated; similarly, switch groups 7, t₆At a time t₇The switch is switched off at any time, and a preset current waveform of the switch group 7 is generated. Wherein Δ t is defined₁＝t₁-t₀This is referred to as the phase difference of switch set 2 relative to switch set 1, and so on.

The waveform shown in fig. 8 can be output by superimposing the waveforms, and in this embodiment, the superimposing circuit is implemented by using an adder circuit constructed by an operational amplifier, where the bandwidth of the operational amplifier is 350 MHz.

The waveform is subjected to low-pass filtering, frequency components above 50MHz are attenuated by second-order RC filtering in the embodiment, the waveform as shown in FIG. 9 can be output, and the current of the waveform is amplified to directly drive the seed laser.

Similarly, adjusting the preset current of each switch, adjusting the on-period of each switch group, adjusting the on-period phase difference between the switch groups can synthesize a plurality of pulse shapes.

And 3, driving the seed laser by adopting the waveform current to enable the energy injected into the amplification stage to change exponentially within a pulse width time, effectively inhibiting the high gain of the amplification stage to the leading edge of the signal and improving the pulse distortion.

Experiments show that the functional module for inhibiting waveform distortion has the characteristics of simple structure, function modularization, high integration level, low cost and simplicity in operation, and can effectively improve waveform distortion of output pulses.