An integrated optoelectronic oscillator

Abstract

This invention discloses an integrated optoelectronic oscillator, relating to the field of microwave photonics technology. It includes an optical link and an electrical link. The optical link comprises a dual-mode laser, an optical coupler, an integrated optical delay line chip, and a photodetector, integrated using photonic wire bonding technology. The dual-mode laser serves as the system's direct-modulation light source and microwave photonic filter. Two optical delay lines of different lengths form a double-loop structure to suppress loop modes. The photodetector converts the dual-mode optical signal into an electrical signal, which is injected into the electrical loop. After amplification, the signal is split by a power divider and fed back onto the dual-mode laser, forming a closed loop to output a microwave signal. This integrated optoelectronic oscillator system significantly reduces the system size and weight of optoelectronic oscillators.

Description

Technical Field

[0001] This invention relates to the field of microwave photonics technology, specifically to an integrated optoelectronic oscillator. Background Technology

[0002] High-quality microwave signals have important applications in communications, radar systems, and sensing. Opto-electronic oscillator (OEO) systems in microwave photonics technology have attracted widespread attention due to their ability to generate microwave signals with low phase noise and high spectral purity. A classic OEO system consists of a laser, modulator, long optical fiber, detector, RF amplifier, and microwave bandpass filter. The oscillation frequency of the system is determined by the microwave bandpass filter. By using long optical fiber as a low-loss energy storage medium, the system's Q value is effectively improved, enabling the OEO to generate high-frequency, low-phase-noise, frequency-tunable, high-quality microwave signals.

[0003] Leveraging the low-loss characteristics of optical fibers, OEO systems typically employ long optical fibers, ranging from several kilometers to tens of kilometers. However, the problem with long optical fibers is the reduced spacing between the optoelectronic oscillation loop modes (the loop mode spacing corresponding to a 10km long optical fiber is 20kHz). This necessitates the use of extremely narrow bandwidth (~kHz) filters to achieve single-mode oscillation, which is currently impractical in the high-frequency microwave band. Furthermore, the large size of optoelectronic oscillator systems, due to the discrete optoelectronic components and the length of the optical fiber, hinders their widespread application. Summary of the Invention

[0004] To address the miniaturization issue of optoelectronic oscillator systems, this invention provides an integrated optoelectronic oscillator system. It employs a multifunctional integrated chip and a hybrid integration method to achieve an integrated optoelectronic oscillator. The integrated optoelectronic oscillator system adopts a dual-ring structure, which is beneficial for suppressing loop modes and improving the quality of the output microwave signal. This solution significantly reduces the size of the optoelectronic oscillator system, and the integration method is simple and easy to implement.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] An integrated optoelectronic oscillator includes optical links and electrical links;

[0007] The optical link includes:

[0008] Dual-mode semiconductor laser: used to generate modulated continuous dual-mode optical signals;

[0009] Coupler I: Used to split a dual-mode optical signal into two beams;

[0010] Waveguide delay line: Used for delay processing of received dual-mode optical signals;

[0011] Coupler II: Used to combine delayed dual-mode optical signals;

[0012] Photodetector: Used to beat the combined dual-mode optical signal to obtain a microwave signal;

[0013] Electrical links include:

[0014] Bias I: Used to input microwave signals into the electrical link;

[0015] Electrical amplifier: Used to amplify the power of microwave signals;

[0016] Electrical coupler: used to split a microwave signal into two paths, resulting in two microwave signals with half the power. One microwave signal is used for the feedback loop, and the other is used for the output.

[0017] Bias converter II: Used to input a portion of the microwave signal split off from the coupler into the modulated dual-mode laser to form a closed optoelectronic oscillation loop;

[0018] A dual-mode laser generates a continuous dual-mode optical signal, which enters coupler I. Coupler I splits the dual-mode optical signal into two paths, each entering an optical delay line waveguide for delay processing. The delayed dual-mode optical signals then enter coupler II, which combines the two delayed signals. The combined dual-mode optical signal enters a photodetector for beat frequency analysis, resulting in a microwave signal. The microwave signal output from the optical link is input into the electrical link via biaser I. The microwave signal input to the electrical link is amplified by an electrical amplifier. The amplified microwave signal is then split into two paths by the electrical coupler, resulting in two microwave signals with halved power. One microwave signal is fed back to the dual-mode laser in the optical link via biaser II, forming a closed photoelectric oscillation loop. The other path is used for output.

[0019] Furthermore, the dual-mode laser is a group III-V indium phosphide-based monolithic integrated semiconductor laser.

[0020] Furthermore, the dual-mode laser serves as the direct-tuned light source and microwave photonic filter of the optoelectronic oscillator system, the beat frequency signal of the dual-mode optical signal serves as the oscillation seed source of the system, and the mode spacing of the dual-mode optical signal ( The oscillation frequency of the photoelectric oscillator system is determined by ( ) ).

[0021]

[0022] in, These are the frequencies corresponding to the two modes, respectively.

[0023] Furthermore, the coupler I, optical delay line, and coupler II are all integrated into a chip based on silicon nitride low-loss material. The specific structure is as follows: 1x2 port coupler I splits and connects two waveguide delay lines of different lengths, and then 1x2 port coupler II combines them.

[0024] Furthermore, two waveguide delay lines of different lengths form two optoelectronic closed loops of different lengths, suppressing loop modes.

[0025] Furthermore, the dual-mode laser, coupler and waveguide delay line integrated chip, and photodetector are integrated using photonic wire bonding.

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

[0027] (1) The present invention achieves an integrated optoelectronic oscillator system by using a multi-functional integrated chip and a hybrid integration scheme, thereby reducing the size and weight of the optoelectronic oscillator system.

[0028] (2) The present invention uses a dual-path optical delay line chip as the energy storage medium of the system, which is beneficial to reducing the size of the system. The two optical waveguide delay lines of the dual-path optical delay line chip have different lengths and different loop mode spacing, which is beneficial to suppressing loop modes. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an integrated optoelectronic oscillator according to an embodiment of the present invention. Detailed Implementation

[0030] The present invention will now be further described with reference to the accompanying drawings.

[0031] To facilitate understanding of this application, the technical solutions of this disclosure will be described in more detail below with reference to the accompanying drawings. However, it should be understood that the embodiments described herein are only for the purpose of fully describing this disclosure and are not all embodiments of this disclosure.

[0032] This embodiment proposes an integrated optoelectronic oscillator. The integrated optoelectronic oscillator is achieved by employing a multifunctional integrated chip and a hybrid integration scheme. The integrated optoelectronic oscillator includes optical and electrical links, as shown in the schematic diagram below. Figure 1 As shown, the optical link includes:

[0033] Dual-mode laser: used to generate modulated continuous dual-mode optical signals;

[0034] Coupler I: Used to split the dual-mode optical signal into two beams;

[0035] Waveguide delay line: used to delay the dual-mode optical signal;

[0036] Coupler II: Used to combine the delayed dual-mode optical signals;

[0037] Photodetector: Used to beat the combined dual-mode optical signal to obtain a microwave signal;

[0038] Electrical links include:

[0039] Bias I: Used to input the microwave signal output by the detector into the electrical link;

[0040] Electrical amplifier: Used to amplify the power of the microwave signal output by the detector;

[0041] Electrical coupler: used to split the microwave signal into two paths, resulting in two microwave signals with half the power. One microwave signal is used for the feedback loop, and the other is used for output.

[0042] Bias converter II: Used to input a portion of the microwave signal split off from the coupler into the modulated dual-mode laser to form a closed optoelectronic oscillation loop.

[0043] A dual-mode laser generates a continuous dual-mode optical signal, which enters coupler I. Coupler I splits the dual-mode optical signal into two paths, each entering an optical delay line waveguide for delay processing. The delayed dual-mode optical signals then enter coupler II, which combines the two delayed signals. The combined dual-mode optical signal is then fed into a photodetector to generate a microwave signal. The microwave signal output from the optical link is input into the electrical link via bias 1. This microwave signal is amplified by an electrical amplifier, and then split into two paths by the electrical coupler, resulting in two microwave signals with halved power. One microwave signal is fed back to the dual-mode laser in the optical link via bias 1, forming a closed photoelectric oscillation loop. The other path is used for output.

[0044] Preferably, the dual-mode laser, coupler I, waveguide delay line and coupler II integrated chip, and photodetector are integrated using photonic wire bonding.

[0045] Preferably, the dual-mode semiconductor laser can be a monolithic integrated semiconductor laser based on indium phosphide (IP) of the III-V group, which outputs a dual-mode optical signal under the drive of a DC signal.

[0046] In this embodiment, a dual-mode semiconductor laser serves as the direct-tuned light source and microwave photonic filter of the optoelectronic oscillator system, and the beat frequency signal of the dual-mode optical signal serves as the oscillation seed source of the system, determining the oscillation frequency of the optoelectronic oscillator system.

[0047] In this embodiment, a dual-loop structure is adopted, with each loop having a different length of optical delay line waveguide and different mode spacing between the two loops, which is beneficial for suppressing side-mode signals.

[0048] In this embodiment, coupler I, optical delay line and coupler II are integrated chips based on low-loss materials such as silicon nitride. The specific structure is that 1x2 port coupler I splits and connects two waveguide delay lines of different lengths, and then 1x2 port coupler II combines them.

[0049] Preferably, the electrical links are integrated on a printed circuit board.

[0050] An integrated optoelectronic oscillator is achieved by employing a multifunctional integrated chip and a hybrid integration scheme. This integrated optoelectronic oscillator includes optical and electrical links. The optical link comprises a dual-mode laser, an optical coupler, an integrated optical delay line chip, and a photodetector, integrated using photonic wire bonding technology. The dual-mode laser serves as the system's direct-modulation light source and microwave photonic filter. Two optical delay lines of different lengths form a double-loop structure to suppress loop modes. The electrical link of the integrated optoelectronic oscillator includes a biaser, an electrical amplifier, an electrical coupler, and a power divider, integrating the electrical components onto a printed circuit board. The dual-wavelength optical signal output from the dual-mode laser is split into two paths by the optical coupler I, each entering one of the two delay lines before being combined and fed into the photodetector. The photodetector converts the dual-mode optical signal into an electrical signal, which is injected into the electrical loop. After amplification by the amplifier, the signal is split again by the power divider and fed back onto the dual-mode laser, forming a closed loop and outputting a microwave signal. This integrated optoelectronic oscillator system significantly reduces the system size and weight of optoelectronic oscillators.

[0051] The above-described embodiments illustrate preferred embodiments of the present invention. These embodiments are for understanding the methods and core ideas of this application, but are not intended to limit the present invention. Modifications or substitutions made to the present invention by those skilled in the art without departing from the principles of the present invention are all considered to be within the scope of protection of the present invention.

Claims

1. An integrated optoelectronic oscillator, comprising an optical link and an electrical link; characterized in that, The optical link includes: Dual-mode semiconductor laser: used to generate modulated continuous dual-mode optical signals; Coupler I: Used to split a dual-mode optical signal into two beams; Waveguide delay line: Used for delay processing of received dual-mode optical signals; Coupler II: Used to combine delayed dual-mode optical signals; Photodetector: Used to beat the combined dual-mode optical signal to obtain a microwave signal; Electrical links include: Bias I: Used to input microwave signals into the electrical link; Electrical amplifier: Used to amplify the power of microwave signals; Electrical coupler: used to split a microwave signal into two paths, resulting in two microwave signals with half the power. One microwave signal is used for the feedback loop, and the other is used for the output. Bias converter II: Used to input a portion of the microwave signal split off from the coupler into the modulated dual-mode laser to form a closed optoelectronic oscillation loop; A dual-mode laser generates a continuous dual-mode optical signal, which enters coupler I. Coupler I splits the dual-mode optical signal into two paths, each entering an optical delay line waveguide for delay processing. The delayed dual-mode optical signals then enter coupler II, which combines the two delayed signals. The combined dual-mode optical signal enters a photodetector for beat frequency analysis, resulting in a microwave signal. The microwave signal output from the optical link is input into the electrical link via biaser I. The microwave signal input to the electrical link is amplified by an electrical amplifier. The amplified microwave signal is then split into two paths by the electrical coupler, resulting in two microwave signals with halved power. One microwave signal is fed back to the dual-mode laser in the optical link via biaser II, forming a closed photoelectric oscillation loop. The other path is used for output. The dual-mode laser is a group III-V indium phosphide-based monolithic integrated semiconductor laser. The dual-mode laser serves as the direct-tuned light source and microwave photonic filter of the optoelectronic oscillator system, the beat frequency signal of the dual-mode optical signal serves as the oscillation seed source of the system, and the mode spacing of the dual-mode optical signal... Determine the oscillation frequency of the photoelectric oscillator system ; ； in, and are the frequencies corresponding to the two modes, respectively; Coupler I, optical delay line and coupler II are all integrated into a chip based on silicon nitride low-loss material. The specific structure is as follows: 1x2 port coupler I splits and connects two waveguide delay lines of different lengths, and then 1x2 port coupler II combines them. Two waveguide delay lines of different lengths form two optoelectronic closed loops of different lengths, suppressing loop modes; The dual-mode laser, coupler and waveguide delay line integrated chip, and photodetector are integrated using photonic wire bonding.

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