INTELLIGENT REAL-TIME FULL-FIELD MEASUREMENT METHOD AND SYSTEM FOR HIGH-REPETITION-RATE FEMTOSECOND PULSE

Abstract

The present invention discloses an intelligent real-time full-field measurement method and system for a high-repetition-rate femtosecond pulse. The method includes: splitting a to-be-tested signal into n channels; performing a frequency reduction separation on each of the channels; splitting each channel of frequency-reduced time-domain demultiplexed signals into two signals, where a small dispersion component performs time-domain stretching on one signal, and a big dispersion component performs a time-frequency conversion on the other signal; acquiring time-domain intensity information of the to-be-tested signal after the stretching by the small dispersion component and frequency-domain envelope information of the to-be-tested signal after the time-frequency conversion by the big dispersion component; and continuously iterating the acquired time-domain intensity information and frequency-domain envelope information according to a Gerchberg-Saxton algorithm until a convergence is achieved, to obtain information about intensity and phase of the to-be-tested signal in a time domain and a frequency domain.

Claims

1. An intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse, comprising the following steps: A, splitting, by an optical splitter component, a to-be-tested signal into n channels of time-domain demultiplexed signals; B, performing, by a high-speed optoelectronic amplitude modulator, a frequency reduction separation on a pulse luster in each of the n channels of the time-domain demultiplexed signals in a time domain for demultiplexing, wherein a pulse repetition rate of the time-domain demultiplexed signal is changed to a quarter of that of the to-be-tested signal, that is, RR.sub.S/4; C, splitting, by a second optical coupler, each channel of frequency-reduced time-domain demultiplexed signals into two signals, wherein a small dispersion component performs time-domain stretching on one of the two signal; and a big dispersion component performs a time-frequency conversion on another one of the two signal, to map frequency-domain information of the to-be-tested signal to a time domain; D, acquiring, by a high-speed-signal acquisition component, time-domain intensity information of the to-be-tested signal after the stretching by the small dispersion component and frequency-domain envelope information of the to-be-tested signal after the time-frequency conversion by the big dispersion component; and E, assigning, by a data processing component, an initial phase to the acquired time-domain intensity information and the acquired frequency-domain envelope information of the to-be-tested signal, and continuously iterating the acquired time-domain intensity information and the acquired frequency-domain envelope information according to a Gerchberg-Saxton algorithm until a convergence is achieved, to obtain information about intensity and phase of the to-be-tested signal in the time domain and a frequency domain, thereby measuring full-field information of a high-repetition-rate femtosecond pulse in real time.

2. The intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to claim 1, wherein the to-be-tested signal is a to-be-tested femtosecond pulse signal with a repetition rate of RR.sub.S.

3. The intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to claim 1, wherein the high-speed optoelectronic amplitude modulator performs modulation by using an arbitrary waveform generator, to generate a square wave signal of which a repetition rate is RR.sub.S/4, and a duration is far greater than that of a single pulse of the to-be-tested signal.

4. The intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to claim 3, wherein a latter square wave signal of the high-speed optoelectronic amplitude modulator is delayed by 1/RR.sub.S from a previous square wave signal of the high-speed optoelectronic amplitude modulator.

5. A system for implementing the intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to claim 1, comprising: an optical splitter component, an arbitrary waveform generator, n high-speed optoelectronic amplitude modulators, n second optical couplers, n small dispersion components, n big dispersion components, a high-speed-signal acquisition component, and a data processing component, wherein the optical splitter component comprises a plurality of first optical couplers configured to split a to-be-tested signal into n channels of pulses; the arbitrary waveform generator generates modulation signals for the n high-speed optoelectronic amplitude modulators; the n channels of pulses are connected to the n high-speed optoelectronic amplitude modulators in a one-to-one correspondence, and the high-speed optoelectronic amplitude modulator is configured to modulate a time domain of the to-be-tested signal, to realize time-domain demultiplexing frequency reduction separation, and form n channels of time-domain demultiplexed signals; the n channels of the time-domain demultiplexed signals are connected to the n second optical couplers in a one-to-one correspondence, the second optical coupler is configured to split each channel of the time-domain demultiplexed signals into two signals, a small dispersion component performs time-domain stretching on one of the two signal, and a big dispersion component performs a time-frequency conversion on another one of the two signal, to map frequency-domain information of the to-be-tested signal to a time domain; and the n channels of the time-domain demultiplexed signals form a total of 2n signals; the n small dispersion components are connected to n signals of the 2n signals in a one-to-one correspondence; and the n big dispersion components are connected to another n signals of the 2n signals in a one-to-one correspondence; the high-speed-signal acquisition component comprises a high-speed photodetector and a high-speed oscilloscope, and is configured to convert optical signals of the 2n signals into electrical signals and acquire data in real time; and the data processing component is a computer device and configured to analyze and process acquired information.

6. The system according to claim 5, wherein the n small dispersion components and the n big dispersion components are all dispersive fibers.

7. The system according to claim 5, wherein a dispersion quantity of each of the n small dispersion components is D.sub.1, and a dispersion quantity of each of the n big dispersion components is D.sub.2, wherein |D.sub.2|>|D.sub.1|.

8. The system according to claim 7, wherein the dispersion quantity D.sub.2 of each of the n big dispersion components meets the following far-field diffraction condition: $l\gg \frac{{\tau }_0^2}{2\pi .Math.{\beta }_2.Math.},$ wherein l represents a length of a dispersive fiber, τ.sub.0 represents a width of a to-be-tested pulse, β.sub.2 represents a second-order dispersion coefficient of a big dispersive fiber, λ.sub.0 represents a spectral width of the to-be-tested pulse, and c represents a light speed in vacuum.

9. A system for implementing the intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to claim 2, comprising: an optical splitter component, an arbitrary waveform generator, n high-speed optoelectronic amplitude modulators, n second optical couplers, n small dispersion components, n big dispersion components, a high-speed-signal acquisition component, and a data processing component, wherein the optical splitter component comprises a plurality of first optical couplers configured to split a to-be-tested signal into n channels of pulses; the arbitrary waveform generator generates modulation signals for the n high-speed optoelectronic amplitude modulators; the n channels of pulses are connected to the n high-speed optoelectronic amplitude modulators in a one-to-one correspondence, and the high-speed optoelectronic amplitude modulator is configured to modulate a time domain of the to-be-tested signal, to realize time-domain demultiplexing frequency reduction separation, and form n channels of time-domain demultiplexed signals; the n channels of the time-domain demultiplexed signals are connected to the n second optical couplers in a one-to-one correspondence, the second optical coupler is configured to split each channel of the time-domain demultiplexed signals into two signals, a small dispersion component performs time-domain stretching on one of the two signal, and a big dispersion component performs a time-frequency conversion on another one of the two signal, to map frequency-domain information of the to-be-tested signal to a time domain; and the n channels of the time-domain demultiplexed signals form a total of 2n signals; the n small dispersion components are connected to n signals of the 2n signals in a one-to-one correspondence; and the n big dispersion components are connected to another n signals of the 2n signals in a one-to-one correspondence; the high-speed-signal acquisition component comprises a high-speed photodetector and a high-speed oscilloscope, and is configured to convert optical signals of the 2n signals into electrical signals and acquire data in real time; and the data processing component is a computer device and configured to analyze and process acquired information.

10. A system for implementing the intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to claim 3, comprising: an optical splitter component, an arbitrary waveform generator, n high-speed optoelectronic amplitude modulators, n second optical couplers, n small dispersion components, n big dispersion components, a high-speed-signal acquisition component, and a data processing component, wherein the optical splitter component comprises a plurality of first optical couplers configured to split a to-be-tested signal into n channels of pulses; the arbitrary waveform generator generates modulation signals for the n high-speed optoelectronic amplitude modulators; the n channels of pulses are connected to the n high-speed optoelectronic amplitude modulators in a one-to-one correspondence, and the high-speed optoelectronic amplitude modulator is configured to modulate a time domain of the to-be-tested signal, to realize time-domain demultiplexing frequency reduction separation, and form n channels of time-domain demultiplexed signals; the n channels of the time-domain demultiplexed signals are connected to the n second optical couplers in a one-to-one correspondence, the second optical coupler is configured to split each channel of the time-domain demultiplexed signals into two signals, a small dispersion component performs time-domain stretching on one of the two signal, and a big dispersion component performs a time-frequency conversion on another one of the two signal, to map frequency-domain information of the to-be-tested signal to a time domain; and the n channels of the time-domain demultiplexed signals form a total of 2n signals; the n small dispersion components are connected to n signals of the 2n signals in a one-to-one correspondence; and the n big dispersion components are connected to another n signals of the 2n signals in a one-to-one correspondence; the high-speed-signal acquisition component comprises a high-speed photodetector and a high-speed oscilloscope, and is configured to convert optical signals of the 2n signals into electrical signals and acquire data in real time; and the data processing component is a computer device and configured to analyze and process acquired information.

11. A system for implementing the intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to claim 4, comprising: an optical splitter component, an arbitrary waveform generator, n high-speed optoelectronic amplitude modulators, n second optical couplers, n small dispersion components, n big dispersion components, a high-speed-signal acquisition component, and a data processing component, wherein the optical splitter component comprises a plurality of first optical couplers configured to split a to-be-tested signal into n channels of pulses; the arbitrary waveform generator generates modulation signals for the n high-speed optoelectronic amplitude modulators; the n channels of pulses are connected to the n high-speed optoelectronic amplitude modulators in a one-to-one correspondence, and the high-speed optoelectronic amplitude modulator is configured to modulate a time domain of the to-be-tested signal, to realize time-domain demultiplexing frequency reduction separation, and form n channels of time-domain demultiplexed signals; the n channels of the time-domain demultiplexed signals are connected to the n second optical couplers in a one-to-one correspondence, the second optical coupler is configured to split each channel of the time-domain demultiplexed signals into two signals, a small dispersion component performs time-domain stretching on one of the two signal, and a big dispersion component performs a time-frequency conversion on another one of the two signal, to map frequency-domain information of the to-be-tested signal to a time domain; and the n channels of the time-domain demultiplexed signals form a total of 2n signals; the n small dispersion components are connected to n signals of the 2n signals in a one-to-one correspondence; and the n big dispersion components are connected to another n signals of the 2n signals in a one-to-one correspondence; the high-speed-signal acquisition component comprises a high-speed photodetector and a high-speed oscilloscope, and is configured to convert optical signals of the 2n signals into electrical signals and acquire data in real time; and the data processing component is a computer device and configured to analyze and process acquired information.

12. The system according to claim 9, wherein the n small dispersion components and the n big dispersion components are all dispersive fibers.

13. The system according to claim 9, wherein a dispersion quantity of each of the n small dispersion components is D.sub.1, and a dispersion quantity of each of the n big dispersion components is D.sub.2, wherein |D.sub.2|>|D.sub.1|.

14. The system according to claim 13, wherein the dispersion quantity D.sub.2 of each of the n big dispersion components meets the following far-field diffraction condition: $l\gg \frac{{\tau }_0^2}{2\pi .Math.{\beta }_2.Math.},$ wherein l represents a length of a dispersive fiber, τ.sub.0 represents a width of a to-be-tested pulse, β.sub.2 represents a second-order dispersion coefficient of a big dispersive fiber, λ.sub.0 represents a spectral width of the to-be-tested pulse, and c represents a light speed in vacuum.

15. The system according to claim 10, wherein the n small dispersion components and the n big dispersion components are all dispersive fibers.

16. The system according to claim 10, wherein a dispersion quantity of each of then small dispersion components is D.sub.1, and a dispersion quantity of each of the n big dispersion components is D.sub.2, wherein |D.sub.2|>|D.sub.1|.

17. The system according to claim 16, wherein the dispersion quantity D.sub.2 of each of the n big dispersion components meets the following far-field diffraction condition: $l\gg \frac{{\tau }_0^2}{2\pi .Math.{\beta }_2.Math.},$ wherein l represents a length of a dispersive fiber, τ.sub.0 represents a width of a to-be-tested pulse, β.sub.2 represents a second-order dispersion coefficient of a big dispersive fiber, λ.sub.0 represents a spectral width of the to-be-tested pulse, and c represents a light speed in vacuum.

18. The system according to claim 11, wherein the n small dispersion components and the n big dispersion components are all dispersive fibers.

19. The system according to claim 11, wherein a dispersion quantity of each of the n small dispersion components is D.sub.1, and a dispersion quantity of each of the n big dispersion components is D.sub.2, wherein |D.sub.2|>|D.sub.1|.

20. The system according to claim 19, wherein the dispersion quantity D.sub.2 of each of the n big dispersion components meets the following far-field diffraction condition: $l\gg \frac{{\tau }_0^2}{2\pi .Math.{\beta }_2.Math.},$ wherein l represents a length of a dispersive fiber, τ.sub.0 represents a width of a to-be-tested pulse, β.sub.2 represents a second-order dispersion coefficient of a big dispersive fiber, λ.sub.0 represents a spectral width of the to-be-tested pulse, and c represents a light speed in vacuum.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a schematic structural diagram of an intelligent real-time full-field measurement system for a high-repetition-rate femtosecond pulse according to an embodiment; and

[0036] FIG. 2 is a schematic diagram of a principle of an intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse according to an embodiment.

DESCRIPTION OF THE EMBODIMENTS

[0037] The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention.

[0038] As shown in FIG. 1 and FIG. 2, an intelligent real-time full-field measurement system for a high-repetition-rate femtosecond pulse includes an optical splitter component 1, an arbitrary waveform generator 2, four high-speed optoelectronic amplitude modulators 3, four second optical couplers 4, four small dispersion components 5, four big dispersion components 6, a high-speed-signal acquisition component 7, and a data processing component 8.

[0039] The optical splitter component 1 includes three first optical couplers. Two of the first optical couplers are both connected to one output end of one first optical coupler, to split a to-be-tested signal 1 into 4 channels of pulses.

[0040] The high-speed-signal acquisition component 7 includes a high-speed photodetector and a high-speed oscilloscope connected thereto.

[0041] Four output ends of the three first optical couplers generated through connection are connected to input ends of the four high-speed optoelectronic amplitude modulators 3 in a one-to-one correspondence. The output ends of the four high-speed optoelectronic amplitude modulators 3 are connected to input ends of the four second optical couplers 4 in a one-to-one correspondence. The four high-speed optoelectronic amplitude modulators 3 are all connected to the arbitrary waveform generator 2. One output end of the second optical coupler 4 is connected to an input end of one small dispersion component 5 in a one-to-one correspondence. Another output end of the second optical coupler 4 is connected to an input end of one big dispersion component 6 in a one-to-one correspondence. Output ends of the four small dispersion components 5 and the four big dispersion components 6 are connected to an input end of the high-speed photodetector. The high-speed oscilloscope is connected to the data processing component 8. The data processing component is a computer device and configured to analyze and process acquired information.

[0042] The to-be-tested signal is a to-be-tested femtosecond pulse signal with a high repetition rate of 1 GHz, and the to-be-tested signal is a pulse laser generated by a device such as an optical maser.

[0043] The small dispersion component 5 and the big dispersion component 6 are all dispersive fibers. A dispersion quantity of the small dispersion component 5 is D.sub.1, and a dispersion quantity of the big dispersion component 6 is D.sub.2, where |D.sub.2|>|D.sub.1|.

[0044] If the frequency-domain information is mapped to a time domain, the dispersion quantity D.sub.2 of the big dispersion component needs to meet the following far-field diffraction condition:

[00002]$l\gg \frac{{\tau }_0^2}{2\pi .Math.{\beta }_2.Math.},$

where

[0045] l represents a length of the dispersive fiber, τ.sub.0 represents a width of a to-be-tested pulse, β.sub.2 represents a second-order dispersion coefficient of the big dispersive fiber, λ.sub.0 represents a spectral width of the to-be-tested pulse, and c represents a light speed in vacuum.

[0046] FIG. 2 shows an intelligent real-time full-field measurement method for a high-repetition-rate femtosecond pulse, including the following steps:

[0047] a. An optical splitter component 1 splits a to-be-tested signal pulse with a repetition rate of 1 GHz into four channels of pulses with a repetition rate of 250 MHz in a time domain.

[0048] b. The four channels of pulses are correspondingly inputted into four high-speed optoelectronic amplitude modulators 3, to form four channels of time-domain demultiplexed signals; and a high-speed optoelectronic amplitude modulator 3 performs a frequency reduction separation on a pulse luster in each channel of pulses in a time domain for demultiplexing, where a second pulse is delayed by 1 ns from a first pulse in an aspect of time t, a third pulse is delayed by 1 ns from the second pulse, and a fourth pulse is delayed by 1 ns from the third pulse, and pulse repetition frequencies of the four channels of time-domain demultiplexed signals are each changed to a quarter of that of the to-be-tested signal.

[0049] The four high-speed optoelectronic amplitude modulators 3 perform modulation by using an arbitrary waveform generator 2.

[0050] c. The four channels of time-domain demultiplexed signals formed by using the high-speed optoelectronic amplitude modulators 3 are correspondingly inputted into four second optical couplers 4; and each channel of time-domain demultiplexed signals are split by one second optical coupler 4 into two signals, where a small dispersion component 5 performs time-domain stretching on one signal; and a big dispersion component 6 performs a time-frequency conversion on the other signal, to map frequency-domain information of the to-be-tested signal to a time domain.

[0051] Specifically, the four channels of time-domain demultiplexed signals form eight signals (a, b, c, d, e, f, g, and h). Some signals (a, c, e, and g) each correspond to a small dispersion component 5 for the time-domain stretching; and the other signals (b, d, f, and h) each correspond to a big dispersion component 6 for a time-frequency conversion, to map the frequency-domain information of the to-be-tested signal to the time domain.

[0052] d. A high-speed photodetector and a high-speed oscilloscope acquire in real time time-domain intensity information I.sub.1(t) of the to-be-tested signal after the stretching by the small dispersion component 5 and frequency-domain envelope information of the to-be-tested signal after the time-frequency conversion by the big dispersion component 6.

[0053] e. A data processing component 8 assigns an initial phase to the acquired intensity information I.sub.1(t) and the envelope information I.sub.2 (t), and continuously iterates the information according to a Gerchberg-Saxton algorithm until a convergence is achieved, to obtain information about intensity and phase of the to-be-tested signal in the time domain and a frequency domain, thereby measuring full-field information of a high-repetition-rate femtosecond pulse in real time.

[0054] The foregoing embodiment is one of the implementations of the present invention, but the implementations of the present invention are not limited by the embodiment and test examples. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be equivalent substitutions and are included within the protection scope of the present invention.