A novel self-oscillating optical frequency comb generator

Abstract

This invention discloses a novel self-oscillating optical frequency comb generator, an OEO loop A, used in conjunction with a continuous spectrum laser and a photoelectric oscillator to generate an optical frequency comb; a signal separation component, connected to the OEO loop A via a 1x15 optical demultiplexer A, used to generate real and imaginary signals; a transmission channel, connected to the signal separation component via a 1x15 optical demultiplexer B, used for signal transmission; and a decoding component, connected to the transmission channel, used to recover the real and imaginary signals and perform decoding processing. The OEO loop A includes a single-mode fiber A, a PIN photodetector, an electrical amplifier A, and a bandpass Bessel filter. This invention demonstrates strong and clear constellation diagrams for receiving signals in a 300Gbps 116-QAM transmission and reception channel over uncompensated fiber optic links of standard single-mode fiber (80km to 240km), exhibiting high applicability in coherent optical communication.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and in particular relates to a novel self-oscillating optical frequency comb generator. Background Technology

[0002] With the continuous improvement of optical fiber communication transmission capacity, increasing the number of WDM channels in order to obtain high data rates has received much attention.

[0003] However, this approach also increases the complexity of photoelectric conversion and produces a much higher data rate than that that photoelectric transmitters and receivers can handle. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a novel self-oscillating optical frequency comb generator, which solves the aforementioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a novel self-oscillating optical frequency comb generator, comprising:

[0006] OEO loop A, used in conjunction with a continuous spectrum laser and an optoelectronic oscillator, is used to generate an optical frequency comb;

[0007] The signal separation component, connected to the OEO loop A via a 1x15 optical decompiler A, is used to generate the real and imaginary signals;

[0008] The transmission channel, connected to the signal separation component via a 1x15 optical demultiplexer B, is used for signal transmission;

[0009] The decoding component, connected to the transmission channel, is used to recover the real and imaginary parts of the signal and perform decoding processing;

[0010] The OEO loop A includes a single-mode fiber A, a PIN photodetector, an electrical amplifier A, and a bandpass Bessel filter. The PIN photodetector is connected to the electrical amplifier A and the single-mode fiber A. The single-mode fiber A is connected to an external signal and a connection spectrum laser. The bandpass Bessel filter is connected to a photoelectric oscillator. The single-mode fiber is connected to a signal separation component through a 1x15 optical decompiler A.

[0011] Based on the above technical solutions, the present invention also provides the following optional technical solutions:

[0012] Further technical solution: The signal separation component includes a rectangular optical filter, a 16QAM modulator A, and a beam splitter A. The rectangular optical filter is connected to a single-mode fiber A through a 1x15 optical demultiplexer A, and the beam splitter A is connected to the transmission channel through a 15x1 optical multiplexer.

[0013] Further technical solution: The transmission channel includes a loop structure of single-mode fiber B and an optoelectronic amplifier B. The single-mode fiber B is connected to the beam splitter A through a 15x1 optical multiplexer, and the optoelectronic amplifier is connected to the single-mode fiber B.

[0014] Further technical solution: The decoding component includes a 90° optical mixer, a DSP digital signal processing module, a decision module, and a 16QAM receiver. The DSP digital signal processing module is connected to the decision module and the 90° optical mixer. The 90° optical mixer is connected to a single-mode fiber B through a 1x15 optical demultiplexer B. The decision module is connected to the 16QAM receiver.

[0015] Further technical solutions include: a zero-difference receiving structure, which is connected to a single-mode fiber B via a 1x15 optical demultiplexer B to generate a new self-oscillating optical frequency comb. The zero-difference receiving structure includes an optoelectronic oscillator B, an OEO loop B, a single-mode fiber C, and a 1x15 optical demultiplexer C. The OEO loop B has the same structure as the OEO loop A, and the OEO loop B is connected to the optoelectronic oscillator B and the 1x15 optical demultiplexer B.

[0016] A further technical solution: The input bit stream of the 16QAM modulator A is generated by a pseudo-random bit sequence generator.

[0017] A further technical solution: The beam splitter A is a beam splitter that injects in-phase optical modulator and quad-phase optical modulator.

[0018] Further technical solution: The loop structure of the single-mode fiber B contains 80km of single-mode fiber per loop and is equipped with an optical amplifier with an optical gain of 18dB. The loop structure of the single-mode fiber B uses a total of three loops.

[0019] Beneficial effects

[0020] This invention provides a novel self-oscillating optical frequency comb generator, which, compared with the prior art, has the following advantages:

[0021] Beneficial effects:

[0022] 1. In the OFC generation scheme, the microwave signal is replaced by a generated optoelectronic oscillator, which defines the frequency interval between the generated carriers. In total, 15 carriers are generated, of which the center carrier on the receiving side is used to generate the local oscillator optical frequency comb (LO-OFC), and the left and right carriers are used for A6QAM data modulation of single-mode fiber in 80km to 240km single-mode fiber. The error vector magnitude, bit error rate, symbol error rate, and Q factor of the received signal in the 300Gbps 116-QAM transmission receiving channel transmitted on an uncompensated fiber link in standard single-mode fiber from 80km to 240km, along with their clear constellation diagram, strongly support the applicability of the proposed scheme in coherent optical communication. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the self-excited oscillation optical frequency comb generation scheme of the present invention and its deployment in a coherent 16QAM transmission network.

[0024] Figure 2 The generation results (a) of the OFC generation scheme of the present invention and the generation of the local oscillator (b) are used to generate an optical frequency comb.

[0025] Figure 3 The simulation results and constellation diagrams for the transmission of the carrier 193.08THz and 193.08THz single-mode fiber B12 THz in optical fibers from 80km to 240km are presented.

[0026] Figure 4 The error vector magnitude and Q-factor of this invention are given.

[0027] Figure label annotations: 1. Opto-oscillator A; 2. Continuous spectrum laser; 3. Bandpass Bessel filter; 4. Electrical amplifier; 5. PIN photodetector; 6. Single-mode fiber A; 7. Optical decompositer A; 8. Rectangular optical filter; 9. Beam splitter A; 10. 16QAM modulator A; 11. Optical multiplexer; 12. Single-mode fiber B; 13. Optical decompositer B; 14. 90° optical mixer; 15. DSP digital signal processing module; 16. Decision module; 17. 16QAM receiver; 18. Opto-oscillator B; 19. Optical decompositer C; 20. OEO loop B. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0030] Please see Figures 1-4 According to one embodiment of the present invention, a novel self-oscillating optical frequency comb generator includes:

[0031] OEO loop A, used in conjunction with continuous spectrum laser 2 and opto-oscillator A1, is used to generate optical frequency comb;

[0032] The signal separation component, connected to the OEO loop A via a 1x15 optical decompiler A7, is used to generate the real and imaginary signals;

[0033] The transmission channel, connected to the signal separation component via a 1x15 optical demultiplexer B, is used for signal transmission;

[0034] The decoding component, connected to the transmission channel, is used to recover the real and imaginary parts of the signal and perform decoding processing;

[0035] The OEO loop A includes a single-mode fiber A6, a PIN photodetector 5, an electrical amplifier A4, and a bandpass Bessel filter 3. The PIN photodetector 5 is connected to the electrical amplifier A4 and the single-mode fiber A6. The single-mode fiber A6 is connected to an external signal and a connection spectrum laser. The bandpass Bessel filter 3 is connected to an opto-oscillator A1. The single-mode fiber is connected to a signal separation component through a 1x15 optical decompiler A7.

[0036] Specifically, the signal separation component includes a rectangular optical filter 8, a 16QAM modulator A10, and a beam splitter A9. The rectangular optical filter 8 is connected to a single-mode fiber A6 via a 1x15 optical decompiler A7. The 16QAM modulator A10 is connected to the beam splitter A9, which is connected to the transmission channel via a 15x1 optical multiplexer 11. The input bit stream of the 16QAM modulator A10 is generated by a pseudo-random bit sequence generator (PRBS). The beam splitter A9 is a beam splitter for injecting in-phase and quad-phase optical modulators. The optical frequency comb generated by the OEO loop A in conjunction with the continuous spectrum laser 2 and the photoelectric oscillator A1 is decompiled by the 1x15 optical decompiler A7, and the decompiled signal passes successively through the rectangular optical filter 8 and the 16QAM modulator A10, which perform signal filtering. The signal after passing through the 16QAM modulator A10 is divided into real and imaginary parts (I and Q) by the fractionator A.

[0037] Specifically, the transmission channel includes a loop structure of single-mode fiber B12 and an opto-amplifier. The single-mode fiber B12 is connected to the beam splitter A9 via a 15x1 optical multiplexer 11. The opto-amplifier is connected to the single-mode fiber B12 and to the decoding component via a 1x15 optical demultiplexer B13. Each loop of the single-mode fiber B12 loop structure contains 80km of single-mode fiber and has an optical gain of 18dB with the opto-amplifier. The single-mode fiber B12 loop structure uses three loops. The purpose of this configuration is to maintain transmission advantage by using the single-mode fiber B12 loop structure in conjunction with the optical amplifier B to maintain the optical signal gain.

[0038] In the above example, those skilled in the art should know that the number of loops in the loop structure of the single-mode fiber B12 is set according to requirements, and not simply set to three.

[0039] Specifically, the decoding component includes a 90° optical mixer 14, a DSP digital signal processing module 15, a decision module 16, and a 16QAM receiver 17. The DSP digital signal processing module 15 is connected to the decision module 16 and the 90° optical mixer 14. The 90° optical mixer 14 is connected to a single-mode fiber B12 via a 1x15 optical demultiplexer B13. The decision module 16 is connected to the 16QAM receiver 17. The 90° optical mixer 14 receives the signal through the 1x15 optical demultiplexer B and recovers the real and imaginary parts (I and Q) of the signal, which are then transmitted to the DSP digital signal processing module 15 for offline DSP processing. A decision is then made, and the decided signal is decoded by a 16QAM modulator.

[0040] Specifically, it also includes: a zero-difference receiving structure, connected to a single-mode fiber B12 via a 1x15 optical demultiplexer B13, for generating a new self-oscillating optical frequency comb. The zero-difference receiving structure includes an opto-oscillator B18, an OEO loop B20, and a 1x15 optical demultiplexer C19. The OEO loop B20 has the same structure as OEO loop A, and is connected to the opto-oscillator B18 and the 1x15 optical demultiplexer B13. An optical zero-difference receiver structure is used, where the local oscillator (LO) source is replaced by the same OFC source used at the transmitter end, such as... Figure 1 As shown, however, the laser source is replaced by the center carrier frequency (193.1 THz), which is reserved for generating the LO self-oscillating OFC source.

[0041] In this embodiment of the invention, the OEO loop A receives one of the two signals separated into two paths and, together with the opto-oscillator A1 and the continuous spectrum laser 2, generates an optical frequency comb. The generated optical frequency comb is decompiled by a 1x15 optical decompiler A7, and the decompiled signal passes through a rectangular optical filter 8 and a 16QAM modulator A10 for signal filtering. The signal after passing through the 16QAM modulator A10 is divided into real and imaginary parts (I and Q) by a fractionator A. A 15x1 optical multiplexer 11 is used to jointly modulate the carrier and inject the data into the transmission channel. The signal is then transmitted to the decoding component through the transmission channel. The transmission channel adopts a loop structure of single-mode fiber B12 and an optical amplifier B to maintain the optical signal gain to preserve the transmission advantage. In the decoding component, a 1x15 optical demultiplexer B with the same number of channels is used to separate the optical signal and identify each carrier. The identified carrier is transmitted to a 90° optical mixer 14 to recover the real and imaginary parts (I and Q) of the signal and transmitted to a DSP digital signal processing module 15 for offline DSP processing. Then, a decision is made, and the decided signal is decoded by a 16QAM receiver 17. At the same time, the separated optical signal at the receiving end passes through a zero-difference receiving structure, which includes an OEO loop A. The local oscillator (LO) source of the zero-difference receiving structure is replaced by the same OFC source used at the transmitter end, and the laser source is replaced by the center carrier frequency (193.1THz). This center carrier frequency is reserved for generating the LO self-oscillating OFC source.

[0042] Simulation results are as follows Figure 2 As shown, the generated comb contains 15 carrier frequencies and has a high carrier-to-noise ratio. The results of the generated OFC and self-oscillating local oscillator can be found in... Figure 2 As seen in the image, the amplitude difference varies from left to right. These carriers are filtered using a rectangular optical filter 8 and passed individually by a 16QAM modulator, with each carrier covering a 20Gb data rate. A beam splitter using injected in-phase and quadrature-phase (IQ) optical modulators separates the filtered signal into real and imaginary parts (I and Q). An optical combiner combines the signals from both ends to produce the desired 16QAM signal.

[0043] The system proposed in this patent performs well in terms of bit error rate, symbol error rate, and Q factor. Figure 3 The BER performance of the proposed scheme is shown under different fiber spans. It can be seen that the scheme provides optimal results for fiber transmissions of 80km and 160km, while the BER value at 240km remains below the threshold. Furthermore, the constellation diagrams for Channel 1 and Channel 2 can also be obtained... Figure 3 As seen in the illustration. Meanwhile, the error vector magnitude, bit error rate, symbol error rate, and Q-factor of the received channel can be... Figure 4As seen in the results, it can be concluded that the proposed OFC generation scheme has the potential to be deployed in single-mode fiber A6QAM coherent optical communication systems with fiber spans ranging from 80km to 240km.

[0044] This invention utilizes SO-OFC generators on both the OLT and ONU sides, replacing the laser array on the OLT side as the transmitter and serving as a local oscillator source on the ONU side. Compared to conventional LiNbO3 MZM, EAM offers superior performance in terms of lower power consumption and faster response. Furthermore, EAM is widely used as a transmitter in high-speed and long-distance optical communication systems due to its ease of integration with relatively small-sized lasers. A self-oscillating OFC is generated through a cascaded configuration of the EAM and polarization controller. The self-oscillating loop is configured using a high-speed PIN photodetector, an electrical amplifier 4, standard single-mode fiber, and a bandpass Bessel filter 3. 20Gbps 16QAM data is modulated on each carrier without using dispersion-compensating fiber in the transmission line. At the receiver, a Gaussian optical filter is used to identify the carrier signal, and a 16QAM receiver 17 detects the in-phase and quadrature phase of the input signal.

[0045] In this invention, the microwave signal is replaced by a generated optoelectronic oscillator in the OFC generation scheme. This oscillator defines the frequency interval between the generated carriers. In total, 15 carriers are generated, with the center carrier on the receiving side used to generate the local oscillator optical frequency comb (LO-OFC), and the left and right carriers used for A6QAM data modulation in 80km to 240km single-mode fiber. The error vector magnitude, bit error rate, symbol error rate, and Q factor of the received signal in the 300Gbps 116-QAM transmission receiving channel transmitted on an uncompensated fiber link of standard single-mode fiber from 80km to 240km, along with their clear constellation diagram, strongly support the applicability of the proposed scheme in coherent optical communication.

[0046] It should be noted that, in this document, relational terms such as first, second, etc., A and B are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A novel self-oscillating optical frequency comb generator, characterized in that, Also includes: OEO loop A, used in conjunction with a continuous spectrum laser (2) and an opto-oscillator A (1), is used to generate an optical frequency comb; The signal separation component is connected to the OEO loop A via a 1x15 optical decompiler A (7) to generate the real and imaginary signals; The transmission channel, connected to the signal separation component via a 1x15 optical demultiplexer B, is used for signal transmission; The decoding component, connected to the transmission channel, is used to recover the real and imaginary parts of the signal and perform decoding processing; The OEO loop A includes a single-mode fiber A (6), a PIN photodetector (5), an electrical amplifier A (4), and a bandpass Bessel filter (3). The PIN photodetector (5) is connected to the electrical amplifier A (4) and the single-mode fiber A (6). The single-mode fiber A (6) is connected to an external signal and a connection spectrum laser. The bandpass Bessel filter (3) is connected to an opto-oscillator A (1). The single-mode fiber is connected to a signal separation component through a 1x15 optical decompiler A (7).

2. The novel self-oscillating optical frequency comb generator according to claim 1, characterized in that, The signal separation component includes a rectangular optical filter (8), a 16QAM modulator A (10), and a beam splitter A (9). The rectangular optical filter (8) is connected to a single-mode fiber A (6) through a 1x15 optical demultiplexer A (7), and the beam splitter A (9) is connected to the transmission channel through a 15x1 optical multiplexer (11).

3. The novel self-oscillating optical frequency comb generator according to claim 1, characterized in that, The transmission channel includes a loop structure of a single-mode fiber B (12) and an opto-amplifier B. The single-mode fiber B (12) is connected to a beam splitter A (9) via a 15x1 optical multiplexer (11), and the opto-amplifier is connected to the single-mode fiber B (12).

4. The novel self-oscillating optical frequency comb generator according to claim 3, characterized in that, The decoding component includes a 90° optical mixer (14), a DSP digital signal processing module (15), a decision module (16), and a 16QAM receiver (17). The DSP digital signal processing module (15) is connected to the decision module (16) and the 90° optical mixer (14). The 90° optical mixer (14) is connected to a single-mode fiber B (12) through a 1x15 optical demultiplexer B (13). The decision module (16) is connected to the 16QAM receiver (17).

5. The novel self-oscillating optical frequency comb generator according to claim 3, characterized in that, Also includes: The zero-difference receiving structure is connected to a single-mode fiber B (12) via a 1x15 optical demultiplexer B (13) to generate a new self-oscillating optical frequency comb. The zero-difference receiving structure includes an opto-oscillator B (18), an OEO loop B (20), and a 1x15 optical demultiplexer C (19). The OEO loop B (20) has the same structure as the OEO loop A. The OEO loop B (20) is connected to the opto-oscillator B (18) and the 1x15 optical demultiplexer B (13).

6. The novel self-oscillating optical frequency comb generator according to claim 2, characterized in that, The input bit stream of the 16QAM modulator A(10) is generated by a pseudo-random bit sequence generator.

7. The novel self-oscillating optical frequency comb generator according to claim 2, characterized in that, The beam splitter A(9) is a beam splitter that injects in-phase optical modulators and quad-phase optical modulators.

8. The novel self-oscillating optical frequency comb generator according to claim 3, characterized in that, The loop structure of the single-mode fiber B(12) contains 80km of single-mode fiber per loop and is equipped with an optical amplifier with an optical gain of 18dB. The loop structure of the single-mode fiber B(12) uses a total of three loops.

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