Radio frequency optical fiber link and implementation method for parallel output of fundamental frequency signal and multiple frequency signal

Abstract

The application discloses a radio frequency optical fiber link and an implementation method for parallel output of a base frequency signal and a multiple frequency signal, and belongs to the technical field of wideband radio frequency signal transmission and processing. The link comprises an optical signal generating unit, an optical signal dividing and combining unit and a multi-channel photoelectric conversion unit. The implementation method comprises the following steps: inputting a base frequency signal into the optical signal generating unit to obtain a modulated optical signal and a local oscillation optical signal; inputting the modulated optical signal and the local oscillation optical signal into the optical signal dividing and combining unit to obtain four combined optical signals; and inputting the four combined optical signals into the multi-channel photoelectric conversion unit to output two radio frequency signals, which are respectively a base frequency signal and a multiple frequency signal. The application significantly expands the output wideband signal capacity of the existing radio frequency optical fiber link, and the output signal has the advantages of pure spectrum, low noise and good phase correlation, and has important application value for realizing wideband radio frequency signal generation and distribution in radio frequency photon sensing equipment in biomedical engineering.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wideband radio frequency signal transmission and processing, and particularly relates to a radio frequency optical fiber link and an implementation method for parallel output of a base frequency signal and a frequency multiplication signal, which can be applied to a radio frequency photon sensing device in biomedical engineering to realize wideband radio frequency signal generation and distribution. BACKGROUND

[0002] Biomedical engineering uses radio frequency photon sensing technology to monitor parameters such as pressure, temperature, pulse, and respiration of the human body with high precision. Radio frequency photon sensing technology has the advantages of high sensitivity, good stability, high resolution, good biological safety, low system complexity, and immunity to electromagnetic interference, and can meet the needs of high-precision and safe monitoring of human parameters in various clinical environments, especially in intensive care units (ICU) and nuclear magnetic resonance (MRI) environments.

[0003] In a radio frequency photon sensing device, a radio frequency signal is modulated onto an optical wave, a high-precision optical sensing unit senses changes in the parameters to be measured of the human body, and the parameter changes are mapped to physical quantities such as amplitude, frequency, and phase of the modulated optical signal. Finally, the modulated optical signal is converted back to a radio frequency signal by a photodetector, and the signal processing part processes and extracts the characteristics of the radio frequency signal changes to obtain the parameters to be measured of the human body. As a key part of radio frequency photon sensing, the radio frequency optical fiber link modulates the radio frequency signal onto the optical wave, uses optical fiber as the transmission medium, directly transmits and distributes the modulated optical signal, and converts the optical signal back to a radio frequency signal at the end. The radio frequency optical fiber link uses the characteristics of optical fiber to achieve wideband, long-distance, low-loss, and electromagnetic interference-free signal transmission. Generally, the radio frequency optical fiber link can only transmit a single low-noise base frequency signal, as described in patent CN 109286442B and a low-noise microwave optical fiber link device and implementation method. When the radio frequency photon sensing system needs to use in-phase base frequency signals and frequency multiplication signals to improve the accuracy of parameter measurement, the traditional radio frequency optical fiber link cannot meet the needs.

[0004] Therefore, the present application provides a radio frequency optical fiber link and an implementation method for parallel output of a base frequency signal and a frequency multiplication signal to at least solve some of the above technical problems. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a radio frequency optical fiber link and an implementation method for parallel output of a base frequency signal and a frequency multiplication signal to at least solve some of the above technical problems.

[0006] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0007] The application discloses a radio frequency optical fiber link with parallel output of base frequency signals and multiple frequency signals, which comprises an optical signal generating unit, an optical signal combining unit and a multi-channel photoelectric conversion unit, the optical signal generating unit is inputted with base frequency signals, the optical signal generating unit is provided with a local oscillation optical signal output end and a modulated optical signal output end, the local oscillation optical signal output end and the modulated optical signal output end are connected with the optical signal combining unit, the optical signal combining unit is provided with a first combined optical signal output end, a second combined optical signal output end, a third combined optical signal output end and a fourth combined optical signal output end, the first combined optical signal output end, the second combined optical signal output end, the third combined optical signal output end and the fourth combined optical signal output end are connected with the multi-channel photoelectric conversion unit, and the multi-channel photoelectric conversion unit is outputted with base frequency signals and multiple frequency signals.

[0008] Further, the optical signal generating unit comprises a laser, a 1*2 optical coupler and an optical modulator, the laser is connected with the 1*2 optical coupler, the 1*2 optical coupler is provided with a first output end and a second output end, the first output end is the local oscillation optical signal output end, the second output end is connected with the optical modulator, the input end of the optical modulator is inputted with base frequency signals, and the output end of the optical modulator is the modulated optical signal output end and outputs modulated optical signals.

[0009] Further, the optical signal combining unit comprises a 90-degree optical mixing coupler, the local oscillation optical signal output end of the 1*2 optical coupler and the modulated optical signal output end of the optical modulator are connected with the input end of the 90-degree optical mixing coupler.

[0010] Further, the multi-channel photoelectric conversion unit comprises a first balanced optical detector and a second balanced optical detector, the first combined optical signal output end and the second combined optical signal output end are connected with the first balanced optical detector, the first balanced optical detector outputs base frequency signals, the third combined optical signal output end and the fourth combined optical signal output end are connected with the second balanced optical detector, and the second balanced optical detector outputs multiple frequency signals.

[0011] Further, the optical powers of the first combined optical signal, the second combined optical signal, the third combined optical signal and the fourth combined optical signal are respectively represented as:

[0012]

[0013]

[0014]

[0015]

[0016] In the formula, A0 is the optical field intensity after power division of the laser, C mC is the electric field loss coefficient of the modulated light signal L C is the electric field loss coefficient of the modulated light signal

[0017] The method for realizing the radio frequency optical fiber link with the base frequency signal and the frequency doubled signal output in parallel comprises the following steps:

[0018] Step 1: inputting the base frequency signal into an optical signal generating unit to obtain a modulated light signal and a local oscillation light signal;

[0019] Step 2: inputting the modulated light signal and the local oscillation light signal into an optical signal synthesizing unit to obtain four synthesized light signals, which are respectively a first synthesized light signal, a second synthesized light signal, a third synthesized light signal and a fourth synthesized light signal;

[0020] Step 3: inputting the four synthesized light signals into a multi-channel photoelectric conversion unit to output two radio frequency signals, which are respectively the base frequency signal and the frequency doubled signal.

[0021] Further, the step 1 is specifically that the base frequency signal is inputted into an optical modulator, and the laser emitted by a laser is split into two paths with equal power through a 1×2 optical coupler; one path is directly outputted as the local oscillation light signal, and the other path enters the optical modulator and obtains the modulated light signal under the amplitude modulation of the inputted base frequency signal.

[0022] Further, the step 2 is specifically that the local oscillation light signal and the modulated light signal are respectively inputted into a 90° optical hybrid coupler, and after being split, phase-shifted, superimposed and beat in the 90° optical hybrid coupler, the four synthesized light signals are obtained, which are respectively the first synthesized light signal, the second synthesized light signal, the third synthesized light signal and the fourth synthesized light signal.

[0023] Further, the optical powers of the first synthesized light signal, the second synthesized light signal, the third synthesized light signal and the fourth synthesized light signal are respectively represented as:

[0024]

[0025]

[0026]

[0027]

[0028] In the formula, A0 is the optical electric field intensity after power splitting of the laser, C m C is the electric field loss coefficient of the modulated light signal L C is the electric field loss coefficient of the modulated light signal

[0029] Further, the step 3 is specifically: the first synthesized optical signal and the second synthesized optical signal are input into a first balanced optical detector for photoelectric subtraction detection, and a base frequency signal is output; the third synthesized optical signal and the fourth synthesized optical signal are input into a second balanced optical detector for photoelectric subtraction detection, and a frequency-doubled signal is output.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The present application obtains four synthesized optical signals by coherent processing of laser light from the same laser, and two of the four are a group, and then photoelectric subtraction detection is performed on the two groups to obtain a base frequency signal and a frequency-doubled signal simultaneously. The method proposed in the present application significantly expands the output broadband signal capability of the existing radio frequency fiber link, and the output signal has the advantages of pure spectrum, low noise, and good phase coherence, and has important application value in the realization of broadband radio frequency signal generation and distribution in biomedical engineering and other equipment. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The figure is a radio frequency fiber link overall block diagram of the present application.

[0033] Figure 2 The figure is an optical signal generation unit block diagram of the present application.

[0034] Figure 3 The figure is an optical signal distribution synthesis unit block diagram of the present application.

[0035] Figure 4 The figure is a multi-channel photoelectric conversion unit block diagram of the present application. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] In the description of the present application, it should be noted that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0038] Embodiment 1

[0039] As Figure 1As shown, a radio frequency optical fiber link with parallel output of a fundamental frequency signal and a harmonic signal includes an optical signal generation unit, an optical signal distribution and synthesis unit, and a multi-channel photoelectric conversion unit. The optical signal generation unit receives a fundamental frequency signal as input and has a local oscillator optical signal output terminal and a modulated optical signal output terminal. Both the local oscillator optical signal output terminal and the modulated optical signal output terminal are connected to the optical signal distribution and synthesis unit. The optical signal distribution and synthesis unit has a first synthesized optical signal output terminal, a second synthesized optical signal output terminal, a third synthesized optical signal output terminal, and a fourth synthesized optical signal output terminal. The first, second, third, and fourth synthesized optical signal output terminals are all connected to the multi-channel photoelectric conversion unit, and the multi-channel photoelectric conversion unit outputs a fundamental frequency signal and a harmonic signal.

[0040] In this embodiment, the radio frequency fiber optic link consists of an optical signal generation unit, an optical signal distribution and combining unit, and a multi-channel photoelectric conversion unit. The fundamental frequency signal is input to the optical signal generation unit, resulting in a modulated optical signal and a local oscillator optical signal. After transmission through a certain distance via optical fiber, the modulated and local oscillator optical signals enter the optical signal distribution and combining unit, outputting four combined optical signals. These four combined optical signals then enter the multi-channel photoelectric conversion unit, outputting two parallel radio frequency signals: a fundamental frequency signal and a frequency-harmonic signal. This embodiment utilizes optical beat aberration to coherently process coherent laser signals from the same source to generate multiple optical signals, and simultaneously generates and transmits coherent frequency-harmonic signals based on the fundamental frequency signal's optical fiber transmission.

[0041] As one embodiment, such as Figure 2 As shown, the optical signal generating unit includes a laser, a 1×2 optical coupler, and an optical modulator. The laser is connected to the 1×2 optical coupler, which has a first output terminal and a second output terminal. The first output terminal is the local oscillator optical signal output terminal, and the second output terminal is connected to the optical modulator. The optical modulator receives a fundamental frequency signal at its input terminal and outputs a modulated optical signal at its output terminal. The fundamental frequency signal is input to the optical modulator. The laser emitted by the laser passes through the 1×2 optical coupler and is split into two paths of equal power; one path is directly output as the local oscillator optical signal; the other path enters the optical modulator and, under the amplitude modulation of the input fundamental frequency signal, obtains a modulated optical signal. The optical modulator is a single-arm driven type, and its operating point is set at the minimum optical power value.

[0042] As one embodiment, such as Figure 3As shown in the figure, the optical signal branching unit includes a 90° optical hybrid coupler, and the local oscillator optical signal output end of the 1x2 optical coupler and the modulated optical signal output end of the optical modulator are connected to the input end of the 90° optical hybrid coupler. The local oscillator optical signal and the modulated optical signal are input into the 90° optical hybrid coupler, and after branching, phase shifting, superimposing and beat in the 90° optical hybrid coupler, four synthesized optical signals are obtained: a first synthesized optical signal, a second synthesized optical signal, a third synthesized optical signal and a fourth synthesized optical signal.

[0043] As one of the embodiments, as shown in the figure, Figure 4 As shown in the figure, the multi-channel photoelectric conversion unit includes a first balanced optical detector and a second balanced optical detector, the first synthesized optical signal output end and the second synthesized optical signal output end are connected to the first balanced optical detector, the first balanced optical detector outputs a base frequency signal, the third synthesized optical signal output end and the fourth synthesized optical signal output end are connected to the second balanced optical detector, and the second balanced optical detector outputs a frequency doubled signal. The first synthesized optical signal and the second synthesized optical signal are input into the first balanced optical detector for photoelectric subtraction detection, and a base frequency signal is output; the third synthesized optical signal and the fourth synthesized optical signal are input into the second balanced optical detector for photoelectric subtraction detection, and a frequency doubled signal is output.

[0044] The following provides an embodiment of a specific calculation scheme of the optical power of the first synthesized optical signal, the second synthesized optical signal, the third synthesized optical signal and the fourth synthesized optical signal:

[0045]

[0046]

[0047]

[0048]

[0049] In the formula, A0 is the photoelectric field intensity after power division of the laser, C m is the electric field loss coefficient of the modulated optical signal, C L is the electric field loss coefficient of the local oscillator optical signal, and φ is the optical wave phase change caused by the base frequency signal. The formula (1), the formula (2), the formula (3) and the formula (4) correspond to the optical power calculation formulas of the first synthesized optical signal, the second synthesized optical signal, the third synthesized optical signal and the fourth synthesized optical signal respectively.

[0050] Embodiment 2

[0051] The method for realizing the radio frequency optical fiber link with parallel output of the base frequency signal and the frequency doubled signal includes the following steps:

[0052] Step 1, input the base frequency signal into the optical signal generation unit to obtain a modulated optical signal and a local oscillator optical signal;

[0053] Step 2, the modulated light signal and the local oscillator light signal input light signal division and synthesis unit, to obtain four-way synthesis light signal, respectively, the first synthesis light signal, the second synthesis light signal, the third synthesis light signal and the fourth synthesis light signal;

[0054] Step 3, the four-way synthesis light signal input multi-channel photoelectric conversion unit, output two-way radio frequency signal, respectively, the fundamental frequency signal and the frequency multiplication signal.

[0055] The embodiment provides a kind of method for simultaneously generating conversion of fundamental frequency signal and frequency multiplication signal, two balanced optical detectors are respectively carried out photoelectric subtraction detection to two-way in input four-way synthesis light signal, then obtain two-way parallel fundamental frequency signal and frequency multiplication signal.

[0056] As one of the embodiments, the step 1 is specifically as follows: the fundamental frequency signal input light modulator, the laser emitted by laser is divided into two ways with equal power by 1x2 optical coupler;One way is directly output as the local oscillator light signal;The other way enters the light modulator, and obtains the modulated light signal under the amplitude modulation of input fundamental frequency signal.

[0057] As one of the embodiments, the step 2 is specifically as follows: the local oscillator light signal and the modulated light signal are input into 90° optical hybrid coupler, and after shunting, phase shifting, superimposing and beat difference in 90° optical hybrid coupler, four-way synthesis light signal is obtained: the first synthesis light signal, the second synthesis light signal, the third synthesis light signal and the fourth synthesis light signal.

[0058] As one of the embodiments, the step 3 is specifically as follows: the first synthesis light signal and the second synthesis light signal input first balanced optical detector for photoelectric subtraction detection, and output to obtain the fundamental frequency signal;The third synthesis light signal and the fourth synthesis light signal input second balanced optical detector for photoelectric subtraction detection, and output to obtain the frequency multiplication signal.

[0059] The following provides a specific calculation scheme embodiment of the first synthesis light signal, the second synthesis light signal, the third synthesis light signal and the fourth synthesis light signal:

[0060]

[0061]

[0062]

[0063]

[0064] In the formula, A0 is the optical field intensity after power division of laser, C m is the electric field loss coefficient of modulated light signal, C Lis the electric field loss coefficient of the local light signal, and φ is the phase change of the light wave caused by the base frequency signal.

[0065] The application provides a novel radio frequency optical fiber link and method for parallel output of a base frequency signal and a frequency multiplication signal, and has the advantages of high performance and simple structure, and has important application value for realization of wideband radio frequency signal generation and distribution for radio frequency photon sensing equipment in biomedical engineering.

[0066] Finally, it should be noted that: the above embodiments are merely the preferred embodiments of the present application to illustrate the technical solutions of the present application, but not limit it, of course, nor limit the patent scope of the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; that is to say, any modification or embellishment made in the spirit of the main design idea and spirit of the present application has no substantial significance, and the technical problems solved are still consistent with the present application, and should be included in the protection scope of the present application; in addition, the technical solutions of the present application are directly or indirectly applied to other related technical fields, which are also included in the patent protection scope of the present application.

Claims

1. A radio frequency optical fiber link with parallel output of a fundamental signal and a frequency multiplied signal, characterized by, The application relates to a multi-channel photoelectric conversion device, which comprises a light signal generating unit, a light signal combining unit and a multi-channel photoelectric conversion unit, the light signal generating unit is inputted with a base frequency signal, the light signal generating unit has a local oscillation light signal output end and a modulated light signal output end, the local oscillation light signal output end and the modulated light signal output end are connected with the light signal combining unit, the light signal combining unit has a first combined light signal output end, a second combined light signal output end, a third combined light signal output end and a fourth combined light signal output end, the first combined light signal output end, the second combined light signal output end, the third combined light signal output end and the fourth combined light signal output end are connected with the multi-channel photoelectric conversion unit, and the multi-channel photoelectric conversion unit is outputted with a base frequency signal and a frequency-doubled signal. The light signal combining unit comprises a 90-degree optical mixing coupler, the local oscillation light signal and the modulated light signal are respectively inputted into the 90-degree optical mixing coupler, after being branched, phase-shifted, superposed and beat in the 90-degree optical mixing coupler, four combined light signals are obtained, and the optical powers of the first combined light signal, the second combined light signal, the third combined light signal and the fourth combined light signal are respectively represented as: (1) (2) (3) (4) wherein A 0 is the optical field intensity of the laser, C m is the electrical field loss factor of the modulated optical signal, C L is the electrical field loss factor of the local optical signal, f is the phase change of the optical wave caused by the baseband signal.

2. The radio frequency optical fiber link of claim 1, wherein, The light signal generating unit comprises a laser, a 1*2 optical coupler and a light modulator, the laser is connected with the 1*2 optical coupler, the 1*2 optical coupler has a first output end and a second output end, the first output end is a local oscillation light signal output end, the second output end is connected with the light modulator, the input end of the light modulator is inputted with a base frequency signal, and the output end of the light modulator is a modulated light signal output end and outputs a modulated light signal.

3. The radio frequency optical fiber link of claim 2, wherein, The light signal combining unit comprises a 90-degree optical mixing coupler, the local oscillation light signal output end of the 1*2 optical coupler and the modulated light signal output end of the light modulator are connected with the input end of the 90-degree optical mixing coupler.

4. The radio frequency optical fiber link of claim 3, wherein, The multi-channel photoelectric conversion unit comprises a first balanced light detector and a second balanced light detector, the first combined light signal output end and the second combined light signal output end are connected with the first balanced light detector, the first balanced light detector outputs a base frequency signal, the third combined light signal output end and the fourth combined light signal output end are connected with the second balanced light detector, and the second balanced light detector outputs a frequency-doubled signal.

5. The method for implementing a radio frequency optical fiber link with parallel output of baseband and frequency multiplied signals, characterized in that, The application further discloses a multi-channel photoelectric conversion method, which comprises the following steps: Step 1, inputting a base frequency signal into the light signal generating unit to obtain a modulated light signal and a local oscillation light signal; Step 2, inputting the modulated light signal and the local oscillation light signal into the light signal combining unit to obtain four combined light signals, which are respectively a first combined light signal, a second combined light signal, a third combined light signal and a fourth combined light signal; Step 3, inputting the four combined light signals into the multi-channel photoelectric conversion unit to output two radio frequency signals, which are respectively a base frequency signal and a frequency-doubled signal; The light signal combining unit comprises a 90-degree optical mixing coupler, the local oscillation light signal and the modulated light signal are respectively inputted into the 90-degree optical mixing coupler, after being branched, phase-shifted, superposed and beat in the 90-degree optical mixing coupler, four combined light signals are obtained, and the optical powers of the first combined light signal, the second combined light signal, the third combined light signal and the fourth combined light signal are respectively represented as: (1) (2) (3) (4) wherein A 0 is the optical field intensity after power splitting of the laser, C m is the electrical field loss factor of the modulated optical signal, C L is the electrical field loss factor of the local optical signal, f is the phase change of the optical wave caused by the baseband signal.

6. The baseband signal and frequency-multiplied signal parallel output radio frequency optical fiber link implementation method according to claim 5, characterized in that, The step 1 is specifically: inputting a base frequency signal into an optical modulator, and the laser emitted by a laser is divided into two paths with equal power through a 1*2 optical coupler; one path is directly output as a local light signal, and the other path enters the optical modulator and obtains a modulated light signal under the amplitude modulation of the input base frequency signal.

7. The method of claim 6, wherein the method further comprises: The step 2 is specifically: inputting the local light signal and the modulated light signal into a 90° optical hybrid coupler respectively, and obtaining four paths of synthesized light signals after shunting, phase shifting, superimposing and beat difference in the 90° optical hybrid coupler, which are a first synthesized light signal, a second synthesized light signal, a third synthesized light signal and a fourth synthesized light signal.

8. The baseband signal and frequency-multiplied signal parallel output RF fiber link implementation method of claim 5, wherein, The step 3 is specifically: inputting the first synthesized light signal and the second synthesized light signal into a first balanced optical detector for photoelectric subtraction detection, and outputting a base frequency signal; inputting the third synthesized light signal and the fourth synthesized light signal into a second balanced optical detector for photoelectric subtraction detection, and outputting a frequency-doubled signal.

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