Broadband radio frequency optical fiber delay assembly based on dispersion optical fiber compensation technology

Abstract

The invention discloses a broadband radio frequency optical fiber time delay assembly based on a dispersion optical fiber compensation technology, which relates to a signal processing technology and comprises an electro-optical conversion transmitting module, an optical fiber distribution network module and a photoelectric conversion receiving module which are in communication connection in sequence, and the electro-optical conversion transmitting module is composed of a DFB light source, a broadband electro-optical modulator and a bias control panel. The external modulation of the light intensity of the radio-frequency signal is realized; the optical fiber distribution network module is composed of an MEMS optical switch matrix, a specific-length optical fiber ring, an Ethernet switch control circuit and a C-band EDFA, and free combination and dispersion compensation of optical fiber channel lengths are achieved. The photoelectric conversion receiving module is composed of a broadband photoelectric detector and a radio frequency gain amplification and equalization circuit, and photoelectric conversion and processing of the optical carrier signal after time delay are achieved. According to the invention, true time delay of sub-millisecond optical signals in an L-Ku wave band range can be realized, and the method is suitable for large-angle scanning of phased array radar beams and large-range time delay processing of electronic warfare signals.

Description

Technical Field

[0001] The present invention belongs to the technical field of signal processing, and in particular relates to a broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology. Background Art

[0002] Fiber-optic delay lines have a wide range of applications in phased array radar beamforming, electronic information countermeasures, and storage. Because they use optical fiber as a storage medium, they offer outstanding advantages such as wide bandwidth, low insertion loss, and light weight. Furthermore, because they are true optical delay lines, they can effectively address the low instantaneous bandwidth issues associated with electrical phase shifters in traditional solutions, significantly improving radar imaging resolution. Currently, most traditional fiber-optic delay lines operate in a point-frequency mode, with delay times typically within tens of microseconds. With the rapid development of radar technology, higher performance requirements are being placed on fiber-optic delay lines. In comparison, fiber-optic delay lines with broadband RF and a large delay range face the phenomenon of periodic amplitude fluctuations in the output electrical signal across a wide bandwidth due to the dispersion of ordinary single-mode optical fibers, which seriously affects the actual use of fiber-optic delay lines. Summary of the Invention

[0003] To address the aforementioned technical issues, the present invention provides a broadband RF fiber delay assembly based on dispersion-compensating fiber technology. The dispersion coefficient of single-mode fiber (ITU-T G652D) is approximately 18 ps / (nm·km). When the fiber length is on the order of tens of kilometers and the transmitted RF signal is in the L-Ku band, the maximum optical signal pulse width is on the order of tens of picoseconds. A precisely matched length of negative dispersion coefficient compensating fiber (TDCF) is introduced into the fiber loop to achieve zero total dispersion throughout the loop.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A broadband radio frequency fiber delay component based on dispersion fiber compensation technology includes three parts: an electro-optical conversion transmitter module, an optical fiber distribution network module, and an optoelectronic conversion receiver module, which are sequentially connected in communication;

[0006] The electro-optical conversion transmitter module consists of a DFB light source, a broadband electro-optical modulator, and a bias control board to achieve external modulation of the RF signal light intensity;

[0007] The fiber distribution network module consists of a MEMS optical switch matrix, a fiber ring of specific length, an Ethernet switch control circuit, and a C-band EDFA. It enables free combination of fiber channel lengths and dispersion compensation, and compensates for optical path loss of optical links.

[0008] The photoelectric conversion receiving module consists of a broadband photoelectric detector, a radio frequency gain amplifier and an equalization circuit, which realizes the photoelectric conversion of the optical signal, the amplification of the radio frequency signal and the broadband equalization.

[0009] The DFB light source outputs an optical carrier with narrow linewidth and low relative intensity. The broadband electro-optical modulator receives the optical carrier output from the DFB light source, modulates the RF signal to be transmitted onto the optical carrier, and outputs it. The bias control board provides a stable bias voltage for the broadband electro-optical modulator, enabling it to operate at a specified orthogonal bias voltage. The MEMS optical switch matrix controls the on / off of corresponding optical path nodes. A specific length optical fiber loop controls the timing delay and dispersion of the internally transmitted optical signal. The Ethernet switch control circuit receives control instructions and provides specified control voltages to each device pin of the MEMS optical switch matrix. The C-band EDFA compensates for various losses generated by components such as optical switches and optical fibers in the preceding optical path. The broadband photodetector receives the optical carrier signal output by the EDFA and performs photoelectric conversion output. The RF gain amplifier and equalizer circuit performs gain amplification and in-band flatness adjustment on the electrical signal.

[0010] Preferably, the DFB light source has an output wavelength of 1550 nm ± 2 nm, a line width of ≤ 2 MHz, and a relative intensity noise of ≤ -150 dBc / Hz.

[0011] Preferably, the broadband electro-optic modulator has an operating bandwidth of 2 GHz to 18 GHz and a bias voltage of 2.5 V.

[0012] Preferably, the bias control board has an operating temperature range of -20°C to +50°C.

[0013] Preferably, the MEMS optical switch matrix is ​​of two types: 2×2 type and 1×2 type, and the switching speed of both types is 200us.

[0014] Preferably, the specific optical fiber ring lengths are 40960 meters, 20480 meters, 10240 meters, 5120 meters, 2560 meters, 1280 meters, 640 meters, 320 meters, 160 meters, 80 meters, 40 meters, 20 meters, and 10 meters, totaling 13 types.

[0015] Preferably, the Ethernet switch control circuit receives a status setting instruction from a host computer and outputs a corresponding voltage switch value to each device pin of the MEMS optical switch matrix.

[0016] Preferably, the C-band EDFA has a gain of 20 dB and a noise figure of 3.5 dB.

[0017] Preferably, the broadband photodetector has an operating bandwidth of 2 GHz to 18 GHz and a responsivity of ≥8.5 mA / mW.

[0018] Preferably, the RF gain amplification and equalization circuit design meets the component operating bandwidth: 2GHz-18GHz, and in-band flatness ≤±3dB.

[0019] The beneficial effects of the present invention are:

[0020] Broadband RF fiber delay components based on dispersion-compensating fiber technology achieve true optical delay for processed signals, effectively offsetting the dispersion effects of traditional fiber transmission and ensuring phase consistency and antenna waveform integrity for broadband RF signals. They are suitable for applications such as phased array radar beamforming and control, and electronic countermeasure information storage. By introducing dispersive fiber and optimizing fiber length and dispersion parameter matching, they achieve true sub-millisecond optical signal delay within the L-Ku band and effectively address the periodic amplitude fluctuations of the delay line output signal across a wide bandwidth. The components are highly integrated and support modular design, facilitating flexible adjustment of delay based on actual needs. This reduces system size and power consumption, reduces reliance on high-frequency electronic components, lowers production costs, and improves reliability and maintainability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural diagram of a broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology of the present invention;

[0022] Figure 2 This is a structural diagram of the fiber optic distribution network module. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned objectives, the present invention adopts the following technical solutions.

[0024] like Figure 1 As shown in the figure, a structural diagram of a broadband RF fiber delay component based on dispersion fiber compensation technology of the present invention is provided, which includes three parts: an electro-optical conversion transmitting module, an optical fiber distribution network module, and an optoelectronic conversion receiving module which are sequentially connected for communication. The components are distinguished based on the functions implemented and the signal flow.

[0025] The electro-optical conversion transmission module is composed of a DFB light source, a broadband electro-optical modulator, and a bias control board. The laser in the DFB light source cooperates with the peripheral power and temperature control circuits to provide the entire component with an optical carrier with stable optical power, narrow linewidth, and low-intensity noise. The optical carrier is input to the optical port of the broadband electro-optical modulator. The bias controller belongs to the peripheral control circuit structure of the broadband electro-optical modulator. It locks the bias point and drift trend of the broadband electro-optical modulator through real-time negative feedback to ensure that the bias voltage of the broadband electro-optical modulator always operates at the orthogonal bias point regardless of changes in the external environment, ensuring that it operates in the linear region. The RF radio frequency signal is fed into the Y-shaped optical waveguide AC signal metal electrode in the broadband electro-optical modulator to achieve optical carrier linear intensity modulation of the RF signal.

[0026] Preferably, the DFB light source has an output wavelength of 1550 nm ± 2 nm, a line width of ≤ 2 MHz, and a relative intensity noise of ≤ -150 dBc / Hz.

[0027] Preferably, the broadband electro-optic modulator has an operating bandwidth of 2 GHz to 18 GHz and a bias voltage of 2.5 V.

[0028] Preferably, the bias control board has an operating temperature range of -20°C to +50°C. The fiber distribution network module consists of a MEMS optical switch matrix, a fiber ring of specific length, an Ethernet switch control circuit, and a C-band EDFA. The MEMS optical switch matrix controls the on / off switching of corresponding optical path nodes; the fiber ring of specific length implements timing delay and dispersion control for internally transmitted optical signals; the Ethernet switch control circuit receives control instructions and provides specified control voltages to the pins of each device in the MEMS optical switch matrix; and the C-band EDFA compensates for various losses incurred by components such as optical switches and optical fibers in the preceding optical path. The implementation of the specified step optical delay can be described as follows: a link is formed by connecting 1 1×2 type optical switches at the beginning and end and 13 2×2 type optical switches in the middle, with lengths of 40960 meters, 20480 meters, 10240 meters, 5120 meters, 2560 meters, 1280 meters, 640 meters, 320 meters, 160 meters, 80 meters, 40 meters, 20 meters, and 10 meters, totaling 13 types of optical fiber rings. By controlling the switching combination of each optical switch channel, the transmission time delay of the modulated optical signal output by the electro-optical conversion transmission module is realized in the optical fiber distribution network module. The optical path structure is as follows Figure 2As shown. This fiber link can achieve optical true delay of 0 meters to 81910 meters, with a minimum step of 10 meters. A single type of fiber ring is interconnected by ordinary optical fiber (G.652D) and dispersion-compensating fiber (TDCF) fused taper. The total length of the two optical fiber sections is the specified length of a single fiber ring. The lengths of the two individual optical fibers must be calculated according to the dispersion coefficient to ensure that the dispersion of this type of fiber ring is minimized under the conditions of the optical ITU-C band, thereby achieving dispersion compensation of optical fibers over long distances. The relevant parameters of 13 types of fiber rings are shown in Table 1. The C-band EDFA compensates for the insertion loss caused by the optical interface, optical fiber, etc. in the preceding optical path. The EDFA operates in the output automatic power control mode to ensure that the optical power received by the optoelectronic conversion receiving module is constant, generally about 2dB lower than the saturation input optical power of the photodetector.

[0029] Table 1

[0030] Preferably, the MEMS optical switch matrix is ​​of two types: 2×2 type and 1×2 type, and the switching speed of both types is 200us.

[0031] Preferably, the Ethernet switch control circuit receives a status setting instruction from a host computer and outputs a corresponding voltage switch value to each device pin of the MEMS optical switch matrix, thereby realizing the on / off setting of two paths of a single optical switch (only one on and one off). The MEMS optical switch pin level setting lookup table corresponding to all optical link delay requirement states is located in the memory of the software system single-chip microcomputer.

[0032] Preferably, the C-band EDFA has a gain of 20 dB and a noise figure of 3.5 dB.

[0033] The optoelectronic conversion receiving module consists of a broadband photodetector, an RF gain amplifier, and an equalization circuit. The broadband photodetector receives the delayed optical signal from the fiber optic distribution network module, performs optoelectronic conversion of the signal through square-law detection, and recovers the RF electrical signal. To compensate for signal loss during the electro-optical and optoelectronic conversion processes in the preceding link and improve indicators such as the signal-to-noise ratio, the broadband photodetector is connected to an RF gain amplifier and equalization circuit to perform gain amplification and in-band flatness adjustment of the electrical signal. The RF network inter-stage matching circuit is well designed, and when amplifying the RF electrical signal, the equalization circuit is well designed to ensure in-band amplitude consistency within the L-Ku band.

[0034] Preferably, the broadband photodetector has an operating bandwidth of 2 GHz to 18 GHz and a responsivity of ≥8.5 mA / mW.

[0035] Preferably, the RF gain amplification and equalization circuit design meets the component operating bandwidth: 2GHz-18GHz, and in-band flatness ≤±3dB.

[0036] In summary, this invention discloses a broadband RF fiber delay assembly based on dispersion-compensating fiber technology, designed to address the problem of signal distortion caused by dispersion effects during fiber transmission of broadband RF signals. By employing dispersion compensation technology, the assembly achieves precise delay control across a wide frequency band while maintaining low insertion loss and high signal integrity. The assembly boasts a compact structure, high reliability, and ease of integration into existing communication and radar systems, offering significant economic and social benefits.

[0037] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology, characterized in that: It includes three parts: electro-optical conversion transmitting module, optical fiber distribution network module, and photoelectric conversion receiving module, which are connected in sequence. The electro-optical conversion transmitter module is used to modulate the optical intensity of the input radio frequency signal to obtain a modulated optical signal; The fiber distribution network module is used to set the transmission time delay by freely combining the lengths of multiple serially connected fiber channels, and to perform dispersion compensation and optical link loss compensation on the modulated optical signal; The photoelectric conversion receiving module is used to perform photoelectric conversion on the delayed optical signal, restore the radio frequency signal, and amplify and equalize it.

2. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 1, characterized in that: The electro-optical conversion transmission module includes a DFB light source, a broadband electro-optical modulator, and a bias control board. The DFB light source is used to output an optical carrier. The broadband electro-optical modulator receives the optical carrier output from the DFB light source, modulates the radio frequency signal to be transmitted, loads it onto the optical carrier, and outputs it. The bias control board provides a stable output bias voltage for the broadband electro-optical modulator, allowing it to operate at a specified orthogonal bias voltage.

3. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 2, characterized in that: The DFB light source has an output wavelength of 1550nm±2nm, a linewidth of ≤2MHz, and a relative intensity noise of ≤-150dBc / Hz. The broadband electro-optical modulator has an operating bandwidth of 2GHz-18GHz and a bias voltage of 2.5V. The bias control board has an operating temperature range of -20°C to +50°C.

4. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 1, characterized in that: The fiber distribution network module includes a MEMS optical switch matrix, optical fiber rings of varying lengths, an Ethernet switch control circuit, and a C-band EDFA. The MEMS optical switch matrix controls the on / off switching of corresponding optical path nodes; the optical fiber rings of varying lengths implement timing delay and dispersion control for internally transmitted optical signals; the Ethernet switch control circuit receives control instructions and provides specified control voltages to the pins of each device in the MEMS optical switch matrix; and the C-band EDFA compensates for various losses generated by the optical switch and optical fiber ring devices in the preceding optical path.

5. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 4, characterized in that: The MEMS optical switch matrix is ​​of two types: 2×2 and 1×2, with a switching speed of 200 μs. The C-band EDFA has a gain of 20 dB and a noise figure of 3.5 dB.

6. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 4, characterized in that: The lengths of the optical fiber rings of different lengths are 40960 meters, 20480 meters, 10240 meters, 5120 meters, 2560 meters, 1280 meters, 640 meters, 320 meters, 160 meters, 80 meters, 40 meters, 20 meters, and 10 meters, totaling 13 types.

7. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 6, characterized in that: A single fiber ring is interconnected by fused tapering of ordinary fiber and dispersion-compensating fiber. The total length of the two fiber segments is the specified length of the single fiber ring. The lengths of the two fiber segments are calculated according to the dispersion coefficient to ensure that the dispersion of the corresponding single fiber ring type is minimized under the conditions of the optical ITU-C band, realizing dispersion compensation of optical fibers over long distances.

8. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 4, characterized in that: The Ethernet switch control circuit receives a status setting instruction from a host computer and outputs a corresponding voltage switch value to each device pin of the MEMS optical switch matrix.

9. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 1, characterized in that: The photoelectric conversion receiving module includes a broadband photodetector and a radio frequency gain amplification and equalization circuit. The broadband photodetector receives the optical carrier signal output by the EDFA and completes the photoelectric conversion output; the radio frequency gain amplification and equalization circuit performs gain amplification and in-band flatness adjustment of the electrical signal.

10. The broadband radio frequency optical fiber delay component based on dispersion optical fiber compensation technology according to claim 9, characterized in that: The broadband photodetector has an operating bandwidth of 2 GHz to 18 GHz and a responsivity of ≥ 8.5 mA / mW. The RF gain amplification and equalization circuit design meets the component operating bandwidth of 2 GHz to 18 GHz and an in-band flatness of ≤ ± 3 dB.

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