Ultra-wideband pulse signal detection method based on time stretching

Abstract

The invention belongs to the field of electromagnetic environment perception, and provides an ultra-wideband pulse signal detection method based on time stretching. The system is composed of a broadband light source, a single-mode long optical fiber, an electro-optical modulator, a photoelectric detector, a data acquisition card and an industrial personal computer. According to the invention, the method does not depend on a heavy and expensive traditional oscilloscope, utilizes the optical signal dispersion principle to stretch the signal time domain, and achieves the detection and sampling of ultra-wideband pulse signals with narrow time domain pulse width and extremely low duty ratio.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic environment sensing, and particularly relates to a method for detecting ultra-wideband pulse signals based on time stretching. Background Technology

[0002] With the development of electronic information technology, the demand for electromagnetic environment detection is increasing. The detection of nanosecond-level ultra-wideband pulse signals is crucial for the electromagnetic compatibility (EMC) design of electronic equipment. However, ultra-wideband pulse signals are characterized by extremely narrow pulse widths and low duty cycles. Due to their small dynamic range, poor resilience, and the large size and high cost of the equipment, traditional signal acquisition systems are difficult to meet the measurement requirements.

[0003] With the maturation and application of microwave photonics, the electric field to be measured can be modulated onto light using a photoelectric field sensor with a high damage threshold, and the laser carrying the electrical signal can be transmitted to the back end for detection using optical fiber.

[0004] The problem of poor resilience has been solved. Due to the extremely narrow time-domain pulse width and extremely low duty cycle of nanosecond-level ultra-wideband signals, although the front-end probe can sense the ultra-wideband signal propagating in space, the back-end struggles to effectively perform analog-to-digital conversion, making it difficult for the system to capture the complete waveform. Furthermore, using a traditional oscilloscope for measurement requires equipment with extremely high sampling rates, which are bulky and expensive.

[0005] With the research and development of microwave photonics technology, there are methods for photon time stretching both domestically and internationally. These methods utilize the principle of dispersion to first stretch the time domain of a picosecond-level supercontinuum pulsed light source, and then modulate the radio frequency signal onto the pulsed light source, thereby achieving time domain stretching of the radio frequency signal and reducing the sampling pressure on backend equipment.

[0006] However, this type of method is more suitable for stretching and acquiring continuous signals; for ultra-wideband signals with a small duty cycle, it is difficult to effectively modulate them onto optical pulses. Summary of the Invention

[0007] To overcome the shortcomings of the above-mentioned technologies, this invention proposes a method for detecting ultra-wideband pulse signals. By modulating the ultra-wideband pulse signal onto a broadband continuous light source and transmitting it through a single-mode optical fiber, effective modulation is achieved. Furthermore, the sampling pressure of the back-end system is reduced through the dispersion effect of the optical fiber.

[0008] The specific technical solution of the present invention is as follows:

[0009] An ultrawideband pulse detection method based on time stretching includes a broadband ASE continuous light source, an MZ electro-optic modulator, a single-mode optical fiber, a data acquisition card, a photodetector, and an industrial control computer.

[0010] Preferably, the ASE continuous light source has a wavelength range of C+L, a flat spectrum with a 3dB bandwidth of 1528nm-1602nm, an optical power of 10dBm, and exhibits continuous natural noise in the time domain.

[0011] Preferably, the MZ electro-optic modulator is biased at 0V. The half-wave voltage is 5.58V.

[0012] Preferably, the single-mode fiber is 50km long and has a dispersion coefficient of 17ps / nm×km.

[0013] Preferably, the data acquisition card is 16-bit with a sampling rate of 400MS / s.

[0014] Preferably, the photodetector has a bandwidth of 1 GHz and is DC blocked.

[0015] Preferably, the industrial control computer includes an RF input interface and integrates time-domain plotting software.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention proposes a system method for detecting ultra-wideband pulse signals. This method is low in cost, occupies little space, requires low hardware sampling rate, and has a simple structure that is easy to integrate and apply. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 It is the broadband ASE light source used in this invention.

[0020] Figure 2 This is a diagram of the ultra-wideband signal detection system of the present invention.

[0021] 1-ASE broadband light source, 2-single-mode long optical fiber, 3-signal source, 4-electro-optic modulator, 5-photodetector, 6-industrial control computer

[0022] Figure 3 (a) is a time-domain diagram of the signal source used in this invention, and (b) is a time-domain diagram of the ultra-wideband signal after stretching in this invention. Detailed Implementation

[0023] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0025] The principle of ultra-wideband signal detection in this invention is as follows:

[0026] Firstly, optical fiber dispersion refers to the phenomenon of signal pulse broadening caused by the different propagation speeds of light waves of different frequencies or modes when the optical signal is transmitted in the optical fiber.

[0027] First, the frequency domain phase change φ(ω) of the light field can be fully expanded into a Taylor series form:

[0028]

[0029] The second-order propagation constant is the main influencing factor on pulse time-domain broadening. The relationship between the dispersion coefficient D and the second-order propagation constant is as follows:

[0030]

[0031] The integral over wavelength λ can be expressed as:

[0032]

[0033] Therefore, the relationship between the dispersion coefficient D and the second-order propagation constant is:

[0034]

[0035] Optical pulse frequency domain:

[0036]

[0037] The photocurrent obtained after time-domain stretching is:

[0038]

[0039] The quantitative relationship between time-domain pulse width and spectral width is as follows:

[0040]

[0041] Therefore, the output pulse width is:

[0042] Alternatively, it can be approximated using the dispersion coefficient D:

[0043] T out =D·L·Δλ ​​(9)

[0044] The above principle will be verified through a specific example below.

[0045] This invention provides an ultra-wideband signal detection system, as shown in the system flowchart. The ultra-wideband signal is modulated onto a broadband ASE (Alternating Current Acoustic Light) source by an electro-optic modulator, and then broadened by long fiber dispersion. After passing through a photodetector, it is converted into an analog electrical signal and the data is saved via a 400M acquisition card, as shown in the figure. The signal source is directly injected into an oscilloscope for observing the signal time domain, as shown in the figure (940 ps). After being stretched by the system, the result is also shown in the figure.

[0046] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0048] In this invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting ultra-wideband pulse signals based on time stretching, characterized in that, It includes an ASE light source, an MZ electro-optic modulator, a single-mode long optical fiber, a data acquisition card, and a photodetector.

2. The ultra-wideband pulse detection method according to claim 1, characterized in that, The ASE light source has a flat spectrum and a 3dB bandwidth of 1528-160nm.

3. The ultra-wideband pulse detection method according to claim 1, characterized in that, The ASE light source has an optical power of 10 dBm.

4. The ultra-wideband pulse detection method according to claim 1, characterized in that, The MZ electro-optic modulator has a half-wave voltage of 5.58V.

5. The ultra-wideband pulse detection method according to claim 1, characterized in that, The single-mode optical fiber is 50 km long and has a dispersion coefficient of 17 ps / nm×km.

6. The ultra-wideband pulse detection method according to claim 1, characterized in that, The data acquisition card has a sampling rate of 400 MS / s.

7. The ultra-wideband pulse detection method according to claim 1, characterized in that, The photodetector has a bandwidth of 1 GHz and is DC blocking.

8. An application of ultra-wideband pulse detection as described in any one of claims 1-7, characterized in that, It can detect Gaussian pulse signals with a base width of 940ps.

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