A method and device for spectral measurement of frequency-domain ghost imaging based on dispersion stretching

Abstract

The present invention discloses a spectral measurement method for frequency-domain ghost imaging based on dispersion stretching. Based on the existing frequency-domain ghost imaging technology based on dispersion stretching, the present invention cuts the target spectrum, and sets multiple dispersion modules with different frequency bands to respectively perform time-domain stretching based on dispersion Fourier transform on multiple optical pulses after spectrum segmentation, and then uses a preset pseudo-random code to simultaneously perform intensity modulation in the time domain on the multiple time-domain stretched optical pulses, thereby realizing time-domain to frequency-domain mapping coding modulation. The present invention also discloses a spectral measurement device for frequency-domain ghost imaging based on dispersion stretching. The present invention can solve the deficiencies of the existing frequency-domain ghost imaging technology based on dispersion stretching in terms of the detection bandwidth range. On the basis of realizing high-precision and large-bandwidth range modulation of the frequency-domain optical field, it can achieve large-bandwidth and high-resolution detection of the spectral target with low-cost detection means, and improve the ability of the frequency-domain ghost imaging technology to detect spectra.

Description

Technical Field

[0001] The present invention relates to a spectral measurement method, and in particular to a frequency-domain ghost imaging spectral measurement method and device based on dispersion stretching. Background Art

[0002] Frequency-domain ghost imaging technology is a new spectral detection method. Analogous to the idea and connotation of spatial-domain ghost imaging technology, frequency-domain ghost imaging exploits the potential of frequency-domain optical field modulation and obtains the target spectral information by performing cross-correlation measurement on the intensity of the frequency-domain optical field. Since the frequency-domain ghost imaging technology only needs to detect the optical power of the target spectrum, it can break through the limitation of the lack of high-sensitivity detectors in special bands and has advantages in anti-interference, low cost, etc. However, in order to achieve high-precision spectral detection, high-resolution spectral encoding needs to be realized by frequency-domain ghost imaging. Several encoding schemes proposed currently applicable to the frequency-domain ghost imaging technology include: (1) using the spectral random intensity fluctuation of the supercontinuum light source itself as the encoding information, but this unknown spectral random encoding needs to be obtained by separate high-resolution spectral detection and essentially cannot reduce the system cost; (2) performing pseudo-random modulation encoding of the spectral intensity on the broadband light source through a commercial programmable optical filter. However, this method is limited by the spectral resolution and modulation speed of the programmable optical filter and is difficult to achieve high-precision modulation and detection of the spectral target.

[0003] In order to break through the current limitation of the spectral pseudo-random coding modulation technology on the frequency-domain ghost imaging technology, dispersion Fourier transform provides a new idea for the pseudo-random modulation of the frequency-domain optical field. Utilizing the frequency-time mapping relationship brought by the dispersion Fourier transform technology, the high-resolution requirement of spectral modulation can be transferred to the more mature time-domain modulation. The time-domain encoding of the system can be generated by an arbitrary waveform generator / ordinary microwave source and modulated onto the stretched time-domain waveform through a Mach-Zehnder intensity modulator. Since there is already a one-to-one mapping relationship between the spectrum and the time-domain waveform at this time, the modulation of the time-domain waveform can also be reflected in the modulation of the spectrum, thereby realizing the modulation mapping between the time domain and the frequency domain. The spectral detection accuracy of the system depends on the stretching degree of the target spectrum in the time domain and the accuracy of the time-domain modulation. Therefore, it is easy to achieve high-resolution detection of the target through mature commercial intensity modulation devices.

[0004] However, this system has been proven in actual experimental verification that the degree of dispersion stretching of the spectrum is limited by the pulse repetition frequency of the mode-locked laser. Excessive stretching of the pulse will cause spectral aliasing in the time domain, resulting in the inability to recover the target spectrum. For a femtosecond pulse laser with a repetition frequency of 10 MHz, currently only a spectral detection with a sub-nanometer degree can be achieved for a spectrum with a bandwidth within 4 nm through this modulation encoding method, and a large bandwidth range cannot be covered. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiency of the existing frequency-domain ghost imaging technology based on dispersion stretching in terms of the detection bandwidth range, and to provide a frequency-domain ghost imaging spectral measurement method based on dispersion stretching, which can achieve large-bandwidth and high-precision spectral measurement.

[0006] The present invention specifically adopts the following technical solutions to solve the above technical problems:

[0007] A frequency-domain ghost imaging spectral measurement method based on dispersion stretching, which performs spectral segmentation on the optical pulse passing through the target to be measured, and obtains a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured; for each sub-segment optical pulse, first perform time-domain stretching on it by using the method of dispersion, and then use a preset time-domain pseudo-random signal to perform intensity encoding on the time-domain stretched sub-segment optical pulse, and finally perform cross-correlation operation between the optical intensity information of the obtained intensity encoding signal and the time-domain pseudo-random signal to restore the spectrum of the frequency sub-segment of the target to be measured contained in the sub-segment optical pulse; splice the spectra of the frequency sub-segments of the target to be measured contained in all sub-segment optical pulses in sequence to obtain the spectrum of the target to be measured.

[0008] Based on the same inventive concept, the following technical solutions can also be obtained:

[0009] A frequency-domain ghost imaging spectral measurement method based on dispersion stretching, which performs spectral segmentation on the optical pulse passing through the target to be measured, and obtains a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured; for each sub-segment optical pulse, first perform time-domain stretching on it by using the method of dispersion, and then use a preset time-domain pseudo-random signal to perform intensity encoding on the time-domain stretched sub-segment optical pulse. The same time-domain pseudo-random signal is used for each sub-segment optical pulse, and the time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal; merge the intensity encoding signals of all sub-segment optical pulses into one path, and perform cross-correlation operation between the optical intensity information of the combined signal and the time-domain pseudo-random signal to restore the spectrum of the target to be measured.

[0010] A frequency-domain ghost imaging spectral measurement method based on dispersion stretching, which performs spectral segmentation on the optical pulse passing through the target to be measured, and obtains a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured; for each sub-segment optical pulse, perform time-domain stretching on it respectively by using the method of dispersion; merge all the time-domain stretched sub-segment optical pulses into one path, and use a preset time-domain pseudo-random signal to perform intensity encoding on the combined signal. The time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal; finally, perform cross-correlation operation between the optical intensity information of the intensity encoding signal of the combined signal and the time-domain pseudo-random signal to restore the spectrum of the target to be measured.

[0011] A spectral measurement device for frequency-domain ghost imaging based on dispersion stretching, comprising:

[0012] A spectral splitting module, configured to split the optical pulse passing through the target to be measured into spectra, and obtain a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured;

[0013] A time-domain stretching and encoding module, configured to, for each sub-segment optical pulse, first perform time-domain stretching on it by means of dispersion, and then perform intensity encoding on the time-domain stretched sub-segment optical pulse with a preset time-domain pseudo-random signal;

[0014] An optical power measurement module, configured to measure the optical intensity information of the intensity encoding signals of the sub-segment optical pulses;

[0015] A signal processing module, configured to perform cross-correlation operation between the optical intensity information of the intensity encoding signals of the sub-segment optical pulses and the corresponding time-domain pseudo-random signals, so as to restore the spectra of the frequency sub-segments of the target to be measured contained in each sub-segment optical pulse; and splice the spectra of the frequency sub-segments of the target to be measured contained in all sub-segment optical pulses in sequence to obtain the spectrum of the target to be measured.

[0016] A spectral measurement device for frequency-domain ghost imaging based on dispersion stretching, comprising:

[0017] A spectral splitting module, configured to split the optical pulse passing through the target to be measured into spectra, and obtain a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured;

[0018] A time-domain stretching and encoding module, configured to, for each sub-segment optical pulse, first perform time-domain stretching on it by means of dispersion, and then perform intensity encoding on the time-domain stretched sub-segment optical pulse with a preset time-domain pseudo-random signal. All sub-segment optical pulses use the same time-domain pseudo-random signal, and the time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal;

[0019] An optical power measurement module, configured to combine the intensity encoding signals of all sub-segment optical pulses into one path and measure the optical intensity information of the combined signal;

[0020] A signal processing module, configured to perform cross-correlation operation between the optical intensity information of the combined signal and the time-domain pseudo-random signal to restore the spectrum of the target to be measured.

[0021] A spectral measurement device for frequency-domain ghost imaging based on dispersion stretching, comprising:

[0022] A spectral splitting module, configured to split the optical pulse passing through the target to be measured into spectra, and obtain a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured;

[0023] A time-domain stretching and encoding module is used to perform time-domain stretching on each sub-segment optical pulse by using dispersion respectively; all the time-domain stretched sub-segment optical pulses are combined into one path, and the combined signal is intensity-encoded with a preset time-domain pseudo-random signal. The time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal;

[0024] An optical power measurement module is used to measure the optical intensity information of the intensity-encoded signal of the combined signal;

[0025] A signal processing module is used to restore the spectrum of the target to be measured by performing a cross-correlation operation between the optical intensity information of the intensity-encoded signal of the combined signal and the time-domain pseudo-random signal.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0027] By cutting the target spectrum and performing time-frequency mapping encoding modulation and power detection based on dispersion stretching on each sub-segment spectrum respectively, the present invention can solve the deficiency of the existing frequency-domain ghost imaging technology based on dispersion stretching in the detection bandwidth range. On the basis of realizing high-precision and large-bandwidth range modulation of the frequency-domain optical field, it can achieve large-bandwidth high-resolution detection of the spectral target with low-cost detection means, and improve the ability of the frequency-domain ghost imaging technology to detect spectra. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the first specific embodiment of the spectral measurement device of the present invention;

[0029] Figure 2 It is a comparison of the time waveforms and pulse spectrum waveforms of the optical pulse before and after passing through the dispersion stretching module;

[0030] Figure 3 After spectrum cutting, Figure 1 It is the modulation principle diagram of the time-frequency mapping encoding realized by the parallel dispersion stretching of the device shown;

[0031] Figure 4 It is a schematic structural diagram of the second specific embodiment of the spectral measurement device of the present invention;

[0032] Figure 5 [[ID=,36]]After spectrum cutting, Figure 4 It is the modulation principle diagram of the time-frequency mapping encoding realized by the parallel dispersion stretching of the device shown;

[0033] Figure 6 It is a schematic structural diagram of the third specific embodiment of the spectral measurement device of the present invention;

[0034] Figure 7 After spectrum cutting,Figure 6 The modulation principle diagram of time-frequency mapping coding realized by the device shown through parallel dispersion stretching. Specific implementation manners

[0035] The idea of the present invention is based on the existing frequency-domain ghost imaging technology based on dispersion stretching. By setting multiple dispersion modules with different frequency bands, time-domain stretching based on dispersion Fourier transform is respectively implemented on multiple optical pulses after spectrum splitting, and then the intensity modulation in the time domain is simultaneously performed on the multiple time-domain stretched optical pulses with a preset pseudo-random code, so as to realize time-domain-frequency-domain mapping coding modulation and overcome the deficiencies of the existing frequency-domain ghost imaging technology in terms of the detection bandwidth range.

[0036] For the convenience of public understanding, the technical solutions of the present invention will be described in detail below through three specific embodiments in conjunction with the accompanying drawings:

[0037] Embodiment 1

[0038] The technical solution adopted in this embodiment is specifically as follows:

[0039] A frequency-domain ghost imaging spectral measurement device based on dispersion stretching, comprising:

[0040] A spectrum splitting module, configured to perform spectrum splitting on the optical pulse passing through the target to be measured, and obtain a series of sub-segment optical pulses respectively containing different frequency sub-bands of the target to be measured;

[0041] A time-domain stretching and coding module, configured to, for each sub-segment optical pulse, first perform time-domain stretching on it by using dispersion, and then perform intensity coding on the time-domain stretched sub-segment optical pulse with a preset time-domain pseudo-random signal;

[0042] An optical power measurement module, configured to measure the optical intensity information of the intensity coding signals of each sub-segment optical pulse;

[0043] A signal processing module, configured to restore the spectrum of the frequency sub-band of the target to be measured contained in each sub-segment optical pulse by performing a cross-correlation operation between the optical intensity information of the intensity coding signals of each sub-segment optical pulse and the corresponding time-domain pseudo-random signal; and splice the spectra of the frequency sub-bands of the target to be measured contained in all sub-segment optical pulses in sequence to obtain the spectrum of the target to be measured.

[0044] As Figure 1As shown (the signal processing module is not shown in the figure), in this embodiment, a mode-locked laser is used as the laser source to generate optical pulses with a stable repetition frequency. After the laser beam passes through the spectral target, it is divided into multiple frequency bands with the same bandwidth and increasing center frequencies by a wavelength division multiplexer. Subsequently, each frequency band realizes the dispersion stretching of the optical pulse in the time domain through a large-dispersion chirped fiber grating with a corresponding bandwidth, and at the same time maps the spectral shape corresponding to this section of the optical pulse to the time domain. Subsequently, the same microwave source is used to intensity-modulate a series of identical pseudo-random coding waveforms onto the stretched time-domain optical pulses of each path through a Mach-Zehnder modulator of each path, obtaining the pulse spectrum corresponding to the intensity coding. The optical signal intensity of each path is detected through the optical power meter set for each path, and the reduction of each section of the spectrum is realized by performing a cross-correlation operation between the detected optical intensity and the pseudo-random coding waveform. Finally, the restored multiple sections of the spectrum are spliced in order to obtain the spectrum of the target to be measured.

[0045] Figure 2 It is the schematic diagram of the dispersion Fourier transform that occurs when the optical pulse passes through the dispersion stretching module. As Figure 2 shown:

[0046] When the optical pulse passes through the dispersion stretching module, the large-dispersion chirped fiber grating introduces a second-order phase modulation to the spectrum of the optical pulse. Under the influence of the dispersion effect, the output optical pulse and the input spectrum satisfy the relationship:

[0047]

[0048] where H(ω) represents the transfer function of the dispersive medium at the angular frequency ω. β2 represents the group velocity dispersion parameter,

[0049] L is the length of the dispersive medium. When the group velocity dispersion parameter is large enough to satisfy the far-field distance in the time domain β2L→∞, the time-domain waveform E2(t) of the output optical pulse after the dispersion Fourier transform will satisfy the relationship ω = t / β2L at the angular frequency ω and time t, and will be proportional to the input pulse spectrum E1(ω). At the same time, the envelope of the output spectrum E2(ω) will be consistent with the input spectrum E1(ω). It can be seen from this that the dispersion Fourier transform will make the time domain of the output optical pulse and the spectrum of the input optical pulse show a one-to-one correspondence, and the greater the dispersion, the more separated the adjacent wavelength components are in time. Therefore, the "frequency domain - time" mapping of the optical pulse can be realized.

[0050] Figure 3 For Figure 1Principle diagram of modulation detection for time-frequency mapping coding of the shown structure. The spectrum of the pulsed laser is divided into four sub-pulses of equal bandwidth in sequence through a wavelength division multiplexing module. The four sub-pulses are respectively subjected to time-domain stretching through the dispersion modules of the corresponding paths, and the time-domain waveform of the stretched pulse is mapped to the spectral envelope shape of the corresponding frequency band, thus realizing the first step of frequency-time mapping. Subsequently, on each branch, an intensity modulator is used to perform intensity modulation with the same content on the dispersion-stretched optical pulse, and the obtained time-domain waveform and spectral shape corresponding to the coding change are as shown in the figure. Since the optical pulse after dispersion stretching realizes the mapping from spectrum to time domain, therefore, performing pseudo-random modulation on the time-domain waveform in the time domain will be mapped one by one to the corresponding spectral positions, thus realizing the pseudo-random coding of the spectrum of each sub-pulse. Since the signal format of the modulation coding to each segment of the spectrum is known, the optical power response detected by the optical power meter corresponding to the nth path is:

[0051] S ni =∫I ni (λ)T n (λ)dλ (2)

[0052] In the formula, I ni (λ) is the frequency-domain optical field distribution of the ith modulation corresponding to the nth sub-segment, and T n (λ) is the frequency-domain distribution of the spectral target in the nth segment. Through N times of modulation coding of the frequency-domain optical field, the reconstructed spectral target of this sub-segment can be given by the second-order correlation algorithm:

[0053]

[0054] In the formula, G n (λ) is the restored spectral target of the nth sub-segment, and A i (t) is the time-domain pseudo-random signal provided by the microwave source. Finally, by splicing the restored multi-segment spectral targets G n (λ), the finally restored spectral target can be obtained as:

[0055] G(λ)=G₁(λ)+G₂(λ)+…G n (λ) (4)

[0056] In order to achieve high-precision restoration of the signal with the least number of modulation times and data volume, the present invention preferably adopts an orthogonal coding scheme based on the Fourier basis. The orthogonal coding mode based on the Fourier basis utilizes the orthogonal relationship between trigonometric functions. Since any spectrum can be decomposed into a sum of a series of mutually orthogonal trigonometric function values:

[0057]

[0058] where Δω is the detected spectral bandwidth, ω₀ is the center frequency of the detected spectrum, Ω is the relative optical frequency, an and b n represent the coefficients of the cosine and sine of the nth-order Fourier series. When the frequency-domain modulated optical field is set as follows:

[0059]

[0060]

[0061] where A represents the average intensity of the optical field. Then, the corresponding spectral intensity integral value can be obtained through integral detection:

[0062]

[0063] The spectral target can be restored through matrix operations

[0064]

[0065] Therefore, the corresponding Fourier time-domain coding signal can be set through a microwave source as:

[0066]

[0067] Embodiment 2

[0068] The technical solution adopted in this embodiment is specifically as follows:

[0069] A frequency-domain ghost imaging spectroscopy measurement device based on dispersion stretching, comprising:

[0070] A spectral splitting module, configured to split the optical pulse passing through the target to be measured into spectra, and obtain a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured;

[0071] A time-domain stretching and coding module, configured to, for each sub-segment optical pulse, first perform time-domain stretching on it by using dispersion, and then perform intensity coding on the time-domain stretched sub-segment optical pulse by using a preset time-domain pseudo-random signal, and the same time-domain pseudo-random signal is used for each sub-segment optical pulse, and the time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal;

[0072] An optical power measurement module, configured to combine the intensity coding signals of all sub-segment optical pulses into one path and measure the optical intensity information of the combined signal;

[0073] A signal processing module, configured to restore the spectrum of the target to be measured by performing a cross-correlation operation between the optical intensity information of the combined signal and the time-domain pseudo-random signal.

[0074] Such as Figure 4As shown (the signal processing module is not shown in the figure), the only difference in the hardware structure between this embodiment and Embodiment 1 is that after following the same frequency-time mapping and time-frequency mapping coding modulation, in Embodiment 2, the multiplexing is performed again in the power detection part, and then the optical power of the combined signal is detected by an optical power meter (i.e., the sum of the total power intensities of each path). The additional condition required for this detection mode based on Embodiment 1 is that the time-domain width of each path signal after dispersion stretching has an integer multiple relationship with the period of the modulation signal.

[0075] Figure 5 It is the modulation detection schematic diagram of the time-frequency mapping coding for Embodiment 2, which more detailedly shows the difference between Embodiment 2 and Embodiment 1 in the detection part. As Figure 5 shown, after the same frequency-time mapping and time-frequency mapping modulation as in Embodiment 1, the pulse spectrum and the pulse time-domain waveform also follow the same changes as in Embodiment 1; while in Embodiment 2, due to the combination of each branch, the signal spectra after combination are spliced together in sequence, and the corresponding time-domain pulse signals overlap with each other within each repetition frequency period without interference. Since only an optical power meter is used to detect the total power of the combined signal spectrum in Embodiment 2, it is required that the Fourier orthogonal coding waveforms modulated on each path of the spliced signal total spectrum also satisfy phase continuity and are known after splicing, so as to ensure that the Fourier orthogonal coding on the total spectrum used for cross-correlation recovery is also complete and known.

[0076] The power detection, calculation, and recovery mechanism of Embodiment 2 is similar to that of Embodiment 1 and can be mathematically expressed as:

[0077]

[0078]

[0079] Embodiment 3

[0080] The technical solution adopted in this embodiment is specifically as follows:

[0081] A frequency-domain ghost imaging spectroscopy measurement device based on dispersion stretching, comprising:

[0082] A spectrum splitting module, configured to split the optical pulse passing through the target to be measured into a series of sub-section optical pulses respectively containing different frequency sub-sections of the target to be measured;

[0083] A time-domain stretching and coding module, configured to respectively stretch each sub-section optical pulse in the time domain by using dispersion; combine all the sub-section optical pulses after time-domain stretching into one path, and perform intensity coding on the combined signal with a preset time-domain pseudo-random signal, and the time-domain width of each sub-section optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal;

[0084] An optical power measurement module for measuring the optical intensity information of the intensity-encoded signal of the combined signal;

[0085] A signal processing module for restoring the spectrum of the target to be measured by performing a cross-correlation operation between the optical intensity information of the intensity-encoded signal of the combined signal and the time-domain pseudo-random signal.

[0086] As Figure 6 shown (the signal processing module is not shown in the figure), which is different from the hardware structure of Embodiment 2 in that: after multi-channel dispersion stretching in Embodiment 3, the multi-channels are directly combined, and after unified time-frequency mapping coding modulation of the combined signals through an intensity modulator, the corresponding power intensity is detected through an optical power meter. This detection mode requires the same conditions as those implemented in Embodiment 2, that is, the time-domain width of each signal after dispersion stretching needs to be an integer multiple of the period of the modulation signal.

[0087] Figure 7 It is the modulation detection schematic diagram of the time-frequency mapping coding of Embodiment 3. Different from Embodiment 2, after stretching by dispersion modules for different frequency bands for each channel, the stretched signals of each channel are directly combined, so that the signal spectra after combining are spliced together in sequence, and the corresponding time-domain pulse signals overlap with each other within each repetition period without interference. Since the overlapping time-domain pulse signals do not interfere with each other within each period, the Fourier coding implemented through the same intensity modulator will be simultaneously mapped to the time-domain pulse signals corresponding to each frequency band and the spectra of the corresponding frequency bands. By ensuring that the time-domain width after dispersion stretching is an integer multiple of the period of the modulation signal, it can be ensured that the Fourier orthogonal coding waveforms modulated in different sub-bands also satisfy phase continuity and are known after spectrum splicing, so that the Fourier orthogonal coding on the total spectrum for cross-correlation recovery is also complete and known.

[0088] The power detection and calculation recovery mechanism of Embodiment 3 is the same as that of Embodiment 2, and can be mathematically expressed as:

[0089]

[0090] In summary, the present invention can break through the common limitations of the repetition frequency of the mode-locked laser and the bandwidth of the spectrum to be stretched on the basis of the existing frequency-domain ghost imaging technology based on dispersion stretching, overcome the deficiencies of the existing frequency-domain ghost imaging technology in the detection bandwidth range and spectrum coding modulation accuracy, and provide a spectral detection method that simultaneously meets the requirements of low cost, large bandwidth, and high-precision detection.

Claims

1. A spectral measurement method of frequency-domain ghost imaging based on dispersion stretching, characterized in that Perform spectral splitting on the optical pulse passing through the target to be measured, obtaining a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured; for each sub-segment optical pulse, first perform time-domain stretching on it by means of dispersion, and then use a preset time-domain pseudo-random signal to perform intensity encoding on the time-domain stretched sub-segment optical pulse. The same time-domain pseudo-random signal is used for each sub-segment optical pulse, and the time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal; merge the intensity encoding signals of all sub-segment optical pulses into one path, and restore the spectrum of the target to be measured by performing a cross-correlation operation between the optical intensity information of the combined signal and the time-domain pseudo-random signal.

2. A spectral measurement method of frequency-domain ghost imaging based on dispersion stretching, characterized in that, Perform spectral splitting on the optical pulse passing through the target to be measured, obtaining a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured; for each sub-segment optical pulse, perform time-domain stretching on it by means of dispersion respectively; merge all the time-domain stretched sub-segment optical pulses into one path, and use a preset time-domain pseudo-random signal to perform intensity encoding on the combined signal. The time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal; finally, restore the spectrum of the target to be measured by performing a cross-correlation operation between the optical intensity information of the intensity encoding signal of the combined signal and the time-domain pseudo-random signal.

3. A spectral measurement device for frequency-domain ghost imaging based on dispersion stretching, characterized in that, Comprising: A spectral splitting module, configured to perform spectral splitting on the optical pulse passing through the target to be measured, obtaining a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured; A time-domain stretching and encoding module, configured to, for each sub-segment optical pulse, first perform time-domain stretching on it by means of dispersion, and then use a preset time-domain pseudo-random signal to perform intensity encoding on the time-domain stretched sub-segment optical pulse. The same time-domain pseudo-random signal is used for each sub-segment optical pulse, and the time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal; An optical power measurement module, configured to merge the intensity encoding signals of all sub-segment optical pulses into one path and measure the optical intensity information of the combined signal; A signal processing module, configured to restore the spectrum of the target to be measured by performing a cross-correlation operation between the optical intensity information of the combined signal and the time-domain pseudo-random signal.

4. A frequency-domain ghost imaging spectroscopy measurement device based on dispersion stretching, characterized in that, Comprising: A spectral splitting module, configured to perform spectral splitting on the optical pulse passing through the target to be measured, obtaining a series of sub-segment optical pulses respectively containing different frequency sub-segments of the target to be measured; A time-domain stretching and encoding module, configured to, for each sub-segment optical pulse, perform time-domain stretching on it by means of dispersion respectively; merge all the time-domain stretched sub-segment optical pulses into one path, and use a preset time-domain pseudo-random signal to perform intensity encoding on the combined signal. The time-domain width of each sub-segment optical pulse after dispersion stretching has an integer multiple relationship with the period of the time-domain pseudo-random signal; An optical power measurement module, configured to measure the optical intensity information of the intensity encoding signal of the combined signal; A signal processing module, configured to restore the spectrum of the target to be measured by performing a cross-correlation operation between the optical intensity information of the intensity encoding signal of the combined signal and the time-domain pseudo-random signal.

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