Microwave photon mixer based on optical add-drop filtering and photoelectric oscillation

Abstract

The invention discloses a microwave photon mixer based on optical add-drop filtering and photoelectric oscillation. The microwave photon mixer comprises a laser, an optical modulation and filtering processing chip, a photoelectric detection unit and a microwave amplifier. Wherein a first optical coupler, a first phase modulator, a second phase modulator, a narrow-band flat-top optical filter, an optical add-drop filter and a second optical coupler are arranged in the optical modulation and filtering processing chip; the photoelectric detection unit comprises a balance detector and a photoelectric detector. The laser outputs optical carriers and is connected with the optical modulation and filtering processing chip to complete radio frequency modulation, local oscillation modulation and sideband selection; wherein the straight-through end of the optical add-drop filter is coupled with the photoelectric detector, then is connected with the microwave amplifier, and then is loaded to the radio frequency input port of the second phase modulator, so that photoelectric oscillation is realized, and a local oscillation signal is generated; and an optical signal output by the second optical coupler is coupled with the balance detector to obtain a required frequency mixing signal. According to the design, an external electric local oscillator source is not needed, the structure is simplified, and the advantage of full integration is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave photonics, and relates to a microwave photon mixer, and in particular to a microwave photon mixer based on optical add / drop filtering and photoelectric oscillation. Background Art

[0002] Mixers are key components at the transmitting and receiving ends of electronic systems. Modern electronic systems have increasing requirements for microwave mixers with wide frequency band, high isolation and large dynamic range. Microwave photonic mixing inherits the advantages of microwave photonic technology such as large bandwidth, tunable frequency, high isolation and no electromagnetic interference, and has inherent technical advantages over traditional microwave mixing. Microwave photonic mixing technology can be roughly divided into different structures based on direct modulation, series external modulation and parallel external modulation. Based on these basic mixing architectures, researchers use different electro-optical modulators to study the optimization of key frequency conversion indicators (efficiency, isolation, nonlinearity), image frequency suppression, self-interference elimination, etc. and propose some optimization methods. However, most of the work requires external electric local oscillators, and in practical applications, the operating frequency is subject to the tuning range of the external electric local oscillator. Therefore, it is necessary to combine microwave photonic mixing technology with photonic signal generation technology to realize tunable microwave photonic mixing with self-generation of local oscillator signals.

[0003] Myunghun Shin et al. proposed a self-generated mixing scheme for local oscillator signals based on a series-connected Maxwell modulator. The scheme uses two Maxwell modulators in cascade. The first stage performs RF modulation, and the second stage modulator is divided into two paths through an optical coupler. One path is combined with a long optical fiber to form an energy storage element, a photodetector, an electric amplifier, etc. to form an optoelectronic oscillator to realize the modulation of the local oscillator signal and the local oscillator signal. The other path is output to the photodetector for photoelectric conversion and outputs a mixing signal. This scheme uses a series-connected microwave photon frequency conversion, and the frequency conversion output has many harmonics. The optoelectronic oscillator requires an electric filter and a long optical fiber delay line, which has a limited tuning range and is not conducive to integration.

[0004] Bo Yang et al. proposed a self-generated frequency conversion scheme for local oscillator signals based on dual parallel MPa modulators. The scheme uses two sub-modulators of the dual parallel MPa modulator to perform local oscillator modulation and intermediate frequency signal modulation respectively. The modulator output signal contains both the local oscillator modulated optical signal and the intermediate frequency modulated optical signal. It is divided into two paths through a coupler. One path is connected to the local oscillator modulation port of the modulator after passing through an optical fiber delay line, a detector, an electrical filter and an electrical amplifier to form an optoelectronic oscillator. The signals output by the two photodetectors have a lot of noise, so an electrical filter must be used, and the tuning range is limited. A long optical fiber delay line is also required, which is not conducive to integration.

[0005] Feng Yang et al. proposed a self-generated frequency conversion scheme for local oscillator signals based on polarization multiplexing dual parallel MPa modulators. In this scheme, the polarization multiplexing dual parallel MPa modulator integrates two dual parallel MPa modulators with different polarization states, which can realize functions such as carrier suppression single sideband and band sideband modulation. Combined with optical filters, the harmonics output by the frequency conversion branch detector are suppressed, and up and down frequency conversion switching can be achieved by adjusting the bias voltage of the modulator. This scheme requires electrical filters and 90° bridges to limit the tuning range. In addition, the use of components such as long optical fiber delay lines and polarization controllers also makes this scheme impossible to integrate. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a microwave photonic mixer based on optical add / drop filtering and optoelectronic oscillation to solve the technical problem in the prior art that the self-generation of local oscillator signals cannot be fully integrated.

[0007] Another object of the present invention is to provide a microwave photonic mixer based on optical add / drop filtering and optoelectronic oscillation to solve the technical problem in the prior art that the link loss of the local oscillator signal self-generation needs to be further reduced.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0009] A microwave photon mixer based on optical add / drop filtering and photoelectric oscillation comprises a laser, an optical modulation and filtering processing chip, a photoelectric detection unit and a microwave amplifier.

[0010] The laser is used to output an optical carrier wave, and is sequentially connected with an optical modulation and filtering processing chip and a photoelectric detection unit from left to right.

[0011] In the optical modulation and filtering processing chip, the input end of the first optical coupler is connected to the laser, and the output end of the first optical coupler is divided into two paths. The first output end of the first optical coupler is connected to the optical input end of the first phase modulator, and the second output end of the first optical coupler is connected to the optical input end of the second phase modulator.

[0012] The optical output end a of the first phase modulator is connected to the input end of the narrow-band flat-top optical filter, and the output end c of the narrow-band flat-top optical filter is connected to the first input end of the second optical coupler.

[0013] The optical output end b of the second phase modulator is connected to the input end of the optical add / drop filter, and the download end d of the optical add / drop filter is connected to the second input end of the second optical coupler.

[0014] The photoelectric detection unit comprises a balanced detector, the first output terminal f1 and the second output terminal f2 of the second optical coupler are both connected to the balanced detector, and the output terminal g of the balanced detector outputs a frequency conversion signal.

[0015] The photoelectric detection unit also includes a photoelectric detector, the through end e of the optical add / drop filter is connected to the photoelectric detector, the photoelectric detector is connected to the microwave amplifier, and the output end of the microwave amplifier is connected to the RF input port of the second phase modulator to form a photoelectric oscillation loop.

[0016] The present invention also has the following technical features:

[0017] The second phase modulator performs local oscillator modulation, and the local oscillator modulated optical signal includes a +1-order sideband, an optical carrier and a -1-order sideband.

[0018] The optical add / drop filter performs sideband selection on the local oscillator modulated optical signal.

[0019] The filtering spectra of the through end e of the optical add / drop filter and the download end d of the optical add / drop filter are complementary. The through end e of the optical add / drop filter is a narrowband notch optical filter, which is used to filter out the optical signal required to realize the optoelectronic oscillation loop. The download end of the optical add / drop filter is a bandpass optical filter, which is used to filter out one of the sidebands of the local oscillator modulation signal.

[0020] The optical add / drop filter is a high-Q-value narrow-bandwidth filter, and the optical add / drop filter can be realized by a micro-ring resonator or a micro-disk resonator.

[0021] The first phase modulator performs radio frequency modulation, and the radio frequency modulated optical signal includes a +1-order sideband, an optical carrier and a -1-order sideband.

[0022] The narrowband flat-top optical filter performs sideband selection on the radio frequency modulated optical signal.

[0023] The narrow-band flat-top optical filter can be realized by cascading microring resonators, cascading microdisk resonators or microring-assisted MZI filters.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] (I) The microwave photon mixer based on optical add / drop filtering and optoelectronic oscillation proposed in the present invention combines microwave photon broadband mixing technology with photonic broadband signal generation technology based on optoelectronic oscillators to achieve broadband tunable microwave photon mixing with self-generation of local oscillator signals.

[0026] (II) The present invention utilizes the complementary characteristics of the filtering spectrum of the two ports of the optical add / drop filter to complete the sideband selection function in the optoelectronic oscillator and the mixing module without the need for an additional optical splitter, thereby simplifying the structure and reducing the link loss.

[0027] (III) The optoelectronic oscillator constructed by the present invention does not require a long optical fiber delay line, and all devices can be chip devices to achieve full chip integration, which can reduce the volume and weight compared with the existing technology.

[0028] (IV) In the present invention, by adjusting the center frequencies of the narrowband flat-top optical filter and the optical add / drop filter, the tuning of the LO and RF operating frequencies and the up / down frequency conversion switching can be achieved, which has great application value and market prospects in broadband, multi-band RF transceivers. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The structure diagram of the microwave photon mixer based on optical add / drop filtering and photoelectric oscillation of the present invention is shown.

[0030] Figure 2 is a schematic diagram of optical spectrum and electrical spectrum at different positions provided by an embodiment of the present invention; Figure 2 (a) is a spectrum diagram of the output signal of the optical output end a of the first phase modulator; Figure 2 (b) is a spectrum diagram of the output signal at the optical output end b of the second phase modulator; Figure 2 (c) is the spectrum output from the output end c of the narrow-band flat-top filter; Figure 2 (d) is the spectrum outputted by the download end d of the optical add / drop filter;

[0031] Figure 2 (e) in FIG. 1 is a spectrum diagram of the output of the through-port e of the optical add / drop filter. Figure 2 (f1) and (f2) are optical spectra outputted from the first output terminal f1 and the second output terminal f2 of the second optical coupler; Figure 2 (g) The electrical spectrum output from the output end g of the balanced detector; where, Figure 2 The dotted line in the graph (c) represents the spectrum of a narrow-band flat-top filter; Figure 2 The dotted lines in (d) and (e) represent the optical spectrum of the optical add / drop filter.

[0032] The meanings of the numbers in the figure are: 1-laser, 2-optical modulation and filtering processing chip, 3-photoelectric detection unit, 4-first optical coupler, 5-first phase modulator, 6-second phase modulator, 7-narrowband flat-top optical filter, 8-optical add-drop filter, 9-second optical coupler, 10-balanced detector, 11-photoelectric detector, 12-microwave amplifier.

[0033] The specific contents of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0034] It should be noted that, unless otherwise specified, all components and devices in the present invention are components and devices known in the prior art.

[0035] The present invention provides a microwave photon mixer based on optical add / drop filtering and photoelectric oscillation, wherein:

[0036] A laser is included for outputting an optical carrier;

[0037] It includes optical modulation and filtering processing chips, which are used for local oscillator modulation, radio frequency modulation, sideband selection, and output of optical signals required for frequency conversion and photoelectric oscillation;

[0038] It includes a photoelectric detection unit for photoelectric conversion, outputting a frequency conversion signal and an electric local oscillation signal generated by a photoelectric oscillator;

[0039] It includes microwave amplifiers for amplifying the electric local oscillator of a photoelectric oscillation loop.

[0040] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0041] Example:

[0042] This embodiment provides a microwave photon mixer based on optical add / drop filtering and photoelectric oscillation, such as Figure 1 As shown, a microwave photon mixer based on optical add / drop filtering and photoelectric oscillation includes a laser 1, an optical modulation and filtering processing chip 2, a photoelectric detection unit 3 and a microwave amplifier 12.

[0043] Specifically, a laser 1 is used to output an optical carrier wave, and is connected to an optical modulation and filtering processing chip 2 and a photoelectric detection unit 3 from left to right;

[0044] like Figure 1 As shown, in the optical modulation and filtering processing chip 2, the input end of the first optical coupler 4 is connected to the laser 1, and the output end of the first optical coupler 4 is divided into two paths. The first output end of the first optical coupler 4 is connected to the optical input end of the first phase modulator 5, and the second output end of the first optical coupler 4 is connected to the optical input end of the second phase modulator 6;

[0045] like Figure 1 As shown, the optical output end a of the first phase modulator 5 is connected to the input end of the narrow-band flat-top optical filter 7, and the output end c of the narrow-band flat-top optical filter 7 is connected to the first input end of the second optical coupler 9;

[0046] like Figure 1As shown, the optical output end b of the second phase modulator 6 is connected to the input end of the optical add / drop filter 8, and the download end d of the optical add / drop filter 8 is connected to the second input end of the second optical coupler 9;

[0047] like Figure 1 As shown, the photoelectric detection unit 3 includes a balanced detector 10, the first output terminal f1 and the second output terminal f2 of the second optical coupler 9 are both connected to the balanced detector 10, and the output terminal g of the balanced detector 10 outputs a frequency conversion signal;

[0048] like Figure 1 As shown, the photoelectric detection unit 3 also includes a photoelectric detector 11, the through end e of the optical add / drop filter 8 is connected to the photoelectric detector 11, the photoelectric detector 11 is connected to the microwave amplifier 12, and the output end of the microwave amplifier 12 is connected to the RF input port of the second phase modulator 6 to form a photoelectric oscillation loop.

[0049] Specifically, the laser 1 is used to output an optical carrier, which is coupled to the optical input end of the optical modulation and filtering processing chip 2. The first optical coupler 4 is used to couple the optical carrier emitted by the laser 1 and split it into two paths, which are input to the first phase modulator 5 and the second phase modulator 6 respectively.

[0050] Specifically, the second phase modulator 6 is used for local oscillator modulation, and the local oscillator modulated optical signal includes a +1-order sideband, an optical carrier and a -1-order sideband; the first phase modulator 5 is used for radio frequency modulation, and the radio frequency modulated optical signal includes a +1-order sideband, an optical carrier and a -1-order sideband.

[0051] Specifically, the optical add / drop filter 8 is a high-Q narrow bandwidth filter, which can be implemented by a microring resonator or a microdisk resonator. Its through-port e and download-port d filtering spectra have complementary characteristics, and can complete the sideband selection function in the optoelectronic oscillator and the mixing module.

[0052] Specifically, the through-end e of the optical add / drop filter 8 is a narrowband notch optical filter. If the +1-order sideband of the local oscillator modulated optical signal is within the stopband of the through-end e of the optical add / drop filter 8, the optical carrier and the -1-order sideband must be within the passband of the through-end e of the optical add / drop filter 8. Conversely, if the -1-order sideband of the local oscillator modulated optical signal is within the stopband of the through-end e of the optical add / drop filter 8, the optical carrier and the +1-order sideband must be within the passband of the through-end e of the optical add / drop filter 8, thereby realizing the phase modulation-intensity modulation conversion. The through-end e of the optical add / drop filter 8 is connected to the optical input end of the photodetector 11 to complete the photoelectric conversion. The radio frequency output port of the photodetector 11 passes through the microwave amplifier 12 and is then connected to the radio frequency input port of the second phase modulator 6 to form an optoelectronic oscillator. The frequency of the local oscillator signal stably oscillated and output by the optoelectronic oscillator is the optical carrier frequency f c The center frequency f of the notch filter stopband OF Difference |fc -f OF |.

[0053] Specifically, the download end d of the optical add / drop filter 8 is a bandpass filter complementary to the through end e. The download end d is a passband at the stopband frequency of the through end e, and can filter out the +1st order sideband or -1st order sideband of the local oscillator modulated optical signal.

[0054] Specifically, the narrowband flat-top optical filter 7 can be realized by a cascaded microring resonator, a cascaded microdisk resonator or a microring-assisted MZI filter. If the +1-order sideband of the RF modulated optical signal is within the passband of the narrowband flat-top optical filter 7, then the optical carrier and the -1-order sideband must be within the stopband of the narrowband flat-top optical filter 7. Conversely, if the -1-order sideband of the RF modulated optical signal is within the passband of the narrowband flat-top optical filter 7, then the optical carrier and the +1-order sideband must be within the stopband of the narrowband flat-top optical filter 7.

[0055] Specifically, the optical coupler 9 combines the RF modulated optical sideband and the LO modulated optical sideband filtered by the narrowband flat-top optical filter 7 and the optical add / drop filter 8, and the combined optical signal is input to the balanced detector 10, and is output as a frequency conversion signal after being photoelectrically converted;

[0056] Specifically, by adjusting the operating frequency of the laser 1, the narrowband flat-top optical filter 7 and the optical add / drop filter 8, the tuning of the local oscillator and the radio frequency operating frequency and the up / down conversion switching can be achieved.

[0057] Specifically, the laser 1, the photoelectric detection unit 3 and the microwave amplifier 12 may be packaged modules or chip devices.

[0058] The specific operation of the microwave photon mixer based on optical add / drop filtering and photoelectric oscillation of the present invention includes the following steps:

[0059] Step 1: The laser 1 outputs an optical carrier which is coupled to the optical input end of the optical modulation and filtering processing chip 2, and is divided into two paths through the first optical coupler 4 and input into the first phase modulator 5 and the second phase modulator 6 respectively.

[0060] Step 2, couple the optical carrier output by the laser 1 to the second phase modulator 6. The optical signal output by the second phase modulator 6 is filtered by the optical add-drop filter 8. The through-end e of the optical add-drop filter 8 is a narrowband notch optical filter to realize the phase modulation-intensity modulation conversion. The through-end e of the optical add-drop filter 8 is coupled with the photodetector 11, and then connected to the microwave amplifier 12. The output end of the microwave amplifier 12 is connected to the RF input port of the second phase modulator 6 to form an optoelectronic oscillator. The relative position of the operating frequency of the laser 1 and the optical add-drop filter 8 is adjusted so that the -1 order sideband and the optical carrier of the local oscillator modulated optical signal are located in the passband of the through-end e of the optical add-drop filter 8, and the +1 order sideband of the local oscillator modulated optical signal is located in the stopband of the through-end e of the optical add-drop filter 8. The optoelectronic oscillator achieves stable output, and the spectrum of the output of the second phase modulator 6 is shown in FIG. Figure 2 As shown in (b) in FIG. 1 , the spectrum output from the through-port e of the optical add / drop filter 8 is shown in FIG. Figure 2 As shown in (e) in FIG. 1 , it can be seen that the filtering at the download end d of the optical add / drop filter 8 is complementary to the filtering at the through end e. The download end d of the optical add / drop filter 8 is a bandpass filter complementary to the through end e. At this time, the +1-order sideband of the local oscillator modulated optical signal can be filtered out. The output spectrum is shown in FIG. Figure 2 As shown in (d) in .

[0061] Step 3: Load the RF signal with frequency f1-f2 to the RF input port of the first phase modulator 5. The spectrum output by the first phase modulator 5 is as shown in FIG. Figure 2 As shown in (a), after filtering by the narrowband flat-top optical filter 7, if the +1-order sideband of the RF modulated optical signal is within the passband of the output end c of the narrowband flat-top optical filter 7, then the optical carrier and the -1-order sideband must be within the stopband of the output end c of the narrowband flat-top optical filter 7. The spectrum of the RF modulated optical signal obtained at the output end c is shown in FIG. Figure 2 As shown in (c) in .

[0062] Step 4: The optical signal output from the download end d of the optical add / drop filter 8 and the optical signal output from the output end c of the narrow-band flat-top optical filter 7 are output through the second optical coupler 9 to obtain a spectrum as shown in FIG. Figure 2 As shown in (f1) and (f2) in FIG. 8 , it can be seen that the output optical signal includes the +1-order sideband of the local oscillator modulated optical signal and the +1-order sideband of the RF modulated optical signal.

[0063] Step 5: The optical signal output by the second optical coupler 9 is coupled to the balanced detector 10, and a mixed signal is obtained through photoelectric conversion, such as Figure 2 As shown in (g) in the figure, the frequency is f1-f LO ~f2-f LO The intermediate frequency signal.

Claims

1. A microwave photon mixer based on optical add / drop filtering and photoelectric oscillation, comprising a laser (1), an optical modulation and filtering processing chip (2), a photoelectric detection unit (3) and a microwave amplifier (12), characterized in that: The laser (1) is used to output an optical carrier wave, and is sequentially connected to an optical modulation and filtering processing chip (2) and a photoelectric detection unit (3) from left to right; In the optical modulation and filtering processing chip (2), the input end of the first optical coupler (4) is connected to the laser (1), the output end of the first optical coupler (4) is divided into two paths, the first output end of the first optical coupler (4) is connected to the optical input end of the first phase modulator (5), and the second output end of the first optical coupler (4) is connected to the optical input end of the second phase modulator (6); The optical output end a of the first phase modulator (5) is connected to the input end of the narrow-band flat-top optical filter (7), and the output end c of the narrow-band flat-top optical filter (7) is connected to the first input end of the second optical coupler (9); The optical output end b of the second phase modulator (6) is connected to the input end of the optical add / drop filter (8), and the download end d of the optical add / drop filter (8) is connected to the second input end of the second optical coupler (9); The photoelectric detection unit (3) comprises a balanced detector (10), the first output end f1 and the second output end f2 of the second optical coupler (9) are both connected to the balanced detector (10), and the output end g of the balanced detector (10) outputs a frequency conversion signal; The photoelectric detection unit (3) further comprises a photoelectric detector (11), the through end e of the optical add / drop filter (8) is connected to the photoelectric detector (11), the photoelectric detector (11) is connected to the microwave amplifier (12), and the output end of the microwave amplifier (12) is connected to the radio frequency input port of the second phase modulator (6), thereby forming a photoelectric oscillation loop.

2. The microwave photonic mixer based on optical add / drop filtering and optoelectronic oscillation according to claim 1, characterized in that: The second phase modulator (6) performs local oscillator modulation, and the local oscillator modulated optical signal includes a +1-order sideband, an optical carrier and a -1-order sideband; The optical add / drop filter (8) performs sideband selection on the local oscillator modulated optical signal.

3. The microwave photonic mixer based on optical add / drop filtering and optoelectronic oscillation according to claim 1, characterized in that: The filtering spectra of the through end e of the optical add / drop filter (8) and the download end d of the optical add / drop filter (8) are complementary. The through end e of the optical add / drop filter (8) is a narrowband notch optical filter, which is used to filter out the optical signal required to realize the optoelectronic oscillation loop. The download end of the optical add / drop filter (8) is a bandpass optical filter, which is used to filter out one of the sidebands of the local oscillator modulation signal.

4. The microwave photonic mixer based on optical add / drop filtering and optoelectronic oscillation according to claim 1, characterized in that: The optical add / drop filter (8) is a high-Q-value narrow-bandwidth filter, and the optical add / drop filter (8) can be realized by a micro-ring resonator or a micro-disk resonator.

5. The microwave photonic mixer based on optical add / drop filtering and optoelectronic oscillation according to claim 1, characterized in that: The first phase modulator (5) performs radio frequency modulation, and the radio frequency modulated optical signal includes a +1-order sideband, an optical carrier and a -1-order sideband; The narrowband flat-top optical filter (7) performs sideband selection on the radio frequency modulated optical signal.

6. The microwave photonic mixer based on optical add / drop filtering and optoelectronic oscillation according to claim 1, characterized in that: The narrow-band flat-top optical filter (7) can be realized by a cascaded micro-ring resonator, a cascaded micro-disk resonator or a micro-ring assisted MZI filter.

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