A method for generating multi-path broadband white noise based on chaotic micro-ring optical frequency comb

Abstract

The present application belongs to the field of communication technology, and particularly relates to a kind of on-chip multi-path broadband white noise generation method based on chaotic micro-ring optical frequency comb, the implementation of the method includes semiconductor laser, micro-ring resonator, arrayed waveguide grating, photodetector, characterized by: the above-mentioned devices are integrated in the same chip substrate;Semiconductor laser output continuous light injection micro-ring resonator will occur four-wave mixing, self-phase modulation, cross-phase modulation and dispersion combined action, and equal-interval chaotic optical frequency comb is output through the straight-through end of micro-ring resonator.Coupling together after a plurality of micro-ring resonators generate chaotic optical frequency comb of different free spectral range, demultiplexing is carried out through arrayed waveguide grating, and finally multi-path broadband noise signal is output.Compared with existing noise source, the structure is simple, and has the advantages of low power consumption, high stability, bandwidth expansion, and solves the problem of lack of multi-path broadband noise signal implementation scheme, and can be applied to the field of secure communication, random number generation, etc.

Description

A method for generating multi-channel broadband white noise based on chaotic micro-ring optical frequency comb Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a method for generating multi-channel ultrawideband white noise based on a chaotic micro-ring optical frequency comb. Background Technology

[0002] Noise sources, as a typical testing and calibration device, play an important role in many fields such as communication, remote sensing, military, and astronomy by inputting precisely known noise into communication systems and devices under test, thereby detecting the ability of communication systems to transmit and receive signals and analyzing the performance of devices.

[0003] Currently, most noise sources are generated based on electronic random processes. Typical noise sources utilize resistive thermal noise, phase jitter of ring oscillators, circuit metastability, and chaotic circuits to generate Gaussian white noise. However, the noise bandwidth generated by these methods is only on the order of MHz, far from meeting current application requirements. Furthermore, these noise sources often require amplification of the output noise using electrical amplifiers, making the entire system more complex. Moreover, as the noise bandwidth increases, the flatness of the output power spectrum deteriorates, thus limiting their widespread adoption and use in practical applications.

[0004] Using photonics to construct noise generation devices can overcome the bottleneck of electronic bandwidth and achieve broadband noise signal generation. Typical generation methods utilize laser phase noise, amplified spontaneous emission noise, and chaotic lasers. For example, phase noise based on a vertical-cavity surface-emitting laser can generate an optical noise signal of nearly 1 GHz [Physical Review E, 2010, 81(5), 051137]; broadband noise signals with a bandwidth of approximately 12 GHz can also be generated using superluminescent diodes combined with photoelectric conversion devices [Optics Letters, 2011, 36(6), 1020-1022]; and optical heterodyne can be achieved using chaotic lasers generated by two semiconductor lasers with external feedback to generate a noise signal with a bandwidth of 16.7 GHz [Optics Letters, 2017, 25(4), 3153-3164]. Compared to noise signals generated by electronic random processes, the bandwidth of noise signals generated by photonics is greatly enhanced.

[0005] However, the aforementioned random signal generation devices typically only output single or dual noise signals, which cannot meet the current application requirements for multi-channel parallelization, such as multi-channel secure communication, multi-target radar detection, and multi-channel parallel Monte Carlo simulation. Therefore, in order to simultaneously meet the current application requirements for high bandwidth and parallelization, it is crucial to develop a high-bandwidth, scalable, uniformly spectral density, highly stable, and easily implemented multi-channel broadband white noise source. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an on-chip multi-channel broadband white noise generation method based on a chaotic micro-ring optical frequency comb.

[0007] The objective of this invention can be achieved by employing the following technical measures: designing an on-chip multi-channel broadband white noise generation method based on a chaotic micro-ring optical frequency comb, comprising:

[0008] The system comprises a chip substrate, a semiconductor laser array, a microring resonator array, an optical waveguide, a waveguide array grating, and a photodetector array. The laser beams output from m semiconductor lasers are transmitted through the optical waveguide and coupled into their corresponding microring resonators. Within the ring waveguide of the microring resonator, a combination of four-wave mixing, self-phase modulation, cross-phase modulation, stimulated Raman scattering, and dispersion occurs, resulting in a chaotic optical frequency comb output through the microring's through-hole. This chaotic optical frequency comb manifests as equally spaced frequency combs in the optical frequency domain and as a randomly fluctuating chaotic signal in the time domain. By designing the radius of the microring resonator, the free spectral range of the generated chaotic optical frequency combs is altered, resulting in a sequentially increasing free spectral range. The final m chaotic optical frequency combs are combined, demultiplexed into n signals by the waveguide array grating, and then photoconverted by the photodetector array to output n channels of broadband white noise.

[0009] In this process, the semiconductor laser, micro-ring resonator, optical waveguide, waveguide array grating, and photodetector are integrated onto the same chip substrate by bonding.

[0010] The microring resonator includes any one of the following structures: all-through, up-and-down channel, non-concentric circle, and racetrack. The ring waveguide and straight waveguide materials of the microring resonator are silicon, lithium niobate, and high-refractive-index-difference-doped glass. The quality factor Q of the selected microring resonator is greater than 10. 5 .

[0011] Specifically, the center wavelength of the output laser from the semiconductor laser must be smaller than the wavelength corresponding to the nearest resonant frequency, i.e., located at the blue detuning point of the resonant peak in the microring resonator. The linewidth of the output laser from the semiconductor laser must be smaller than the linewidth of the resonant peak in the microring resonator to ensure that the pump light can couple into the ring waveguide of the microring resonator.

[0012] The free spectral range of the chaotic microring optical frequency comb can be achieved by changing the perimeter of the microring resonator, with the radius of the microring resonator increasing sequentially. The free spectral range of the chaotic microring optical frequency comb is calculated using the following formula: .in, λ represents the free spectral range of the microring resonator, λ is the center wavelength of the laser output light, and n g Let be the group refractive index of the microring resonator waveguide, and L be the perimeter of the microring resonator.

[0013] When using waveguide array gratings for demultiplexing, the channel bandwidth of the waveguide array grating should be much larger than the linewidth of a single comb tooth of the chaotic optical frequency comb, and each channel must contain multiple spectral modes.

[0014] In this system, m chaotic micro-ring optical frequency combs with different free spectral ranges are coupled to the same waveguide and then demultiplexed into n signals by a waveguide array grating. Each signal contains multiple modes. Beat frequencies between modes detuned at different frequencies generate white noise at their respective center frequencies. White noise from different frequency bands is spliced ​​together to ultimately produce broadband white noise. Furthermore, by changing the channel bandwidth of the waveguide array grating, more modes in the channel can participate in beat frequency interactions, which can further improve the white noise bandwidth.

[0015] The advantages and positive effects of the multi-channel broadband white noise generation method based on chaotic micro-ring optical frequency comb provided by the present invention are as follows:

[0016] 1. This technical solution proposes an on-chip multi-channel white noise generation method based on chaotic micro-ring optical frequency comb. Compared with existing technical solutions, it has the advantages of simple structure, smaller size, low power consumption and high stability, which can meet the current application requirements for high bandwidth and parallelization.

[0017] 2. This technical solution combines wavelength division multiplexing (WDM) technology to generate multiple broadband white noise signals. By increasing the channel bandwidth of the waveguide array grating, higher bandwidth white noise generation can be achieved, exhibiting bandwidth scalability. Attached Figure Description

[0018] Figure 1 is a schematic diagram of a multi-channel broadband white noise generation method based on a chaotic micro-ring optical frequency comb provided by the present invention.

[0019] Figure 2 is a schematic diagram of the spectrum of a single chaotic optical frequency comb according to a multi-channel broadband white noise generation method based on a chaotic micro-ring optical frequency comb provided by the present invention.

[0020] Figure 3 is a schematic diagram of the single-channel signal spectrum of a multi-channel broadband white noise generation method based on a chaotic micro-ring optical frequency comb provided by the present invention.

[0021] Figure 4 is a schematic diagram of the power spectrum of a single signal in a multi-channel broadband white noise generation method based on a chaotic micro-ring optical frequency comb provided by the present invention. Detailed Implementation

[0022] The technical measures of the present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can have a clearer understanding of the purpose, advantages, and technical measures of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the practical examples in the present invention, any other practical examples obtained by other skilled in the art without creative effort can be classified as within the protection scope of the present invention.

[0023] As shown in Figure 1, the structure of the on-chip multi-channel broadband white noise generation method based on chaotic micro-ring optical frequency comb provided by the present invention includes: chip substrate 1, semiconductor laser 2, micro-ring resonant cavity 3, optical waveguide 4, waveguide array grating 5, and photodetector array 6.

[0024] The semiconductor laser 2, microring resonator 3, optical waveguide 4, waveguide array grating 5, and photodetector array 6 are all integrated on the chip substrate 1. The laser emitted by the semiconductor laser 2 is used as pump light and coupled into the microring resonator 3. Within the microring resonator 3, a combination of four-wave mixing, self-phase modulation, cross-phase modulation, stimulated Raman scattering, and dispersion occurs, resulting in significant spectral broadening. The microring resonator 3 generates m chaotic microring optical frequency combs with different free spectral ranges. These combs are then coupled to a waveguide and connected to the waveguide array grating 5. The waveguide array grating 5 demultiplexes n signals, each containing multiple modes. When modes with different center wavelengths converge, the corresponding mode beat frequencies generate white noise in different frequency bands. The center frequency of each band is determined by the frequency difference between the corresponding modes. By appropriately selecting the optical frequency differences of each band, the resulting bands with different center frequencies are spliced ​​together to achieve a high-bandwidth white noise signal. Finally, the photodetector array 6 outputs multiple channels of broadband white noise.

[0025] Specifically, this invention uses a silicon photonics chip as a substrate and integrates a semiconductor laser, a microring resonator, an optical waveguide, a waveguide array grating, and a photodetector onto the chip via bonding. The microring resonator described in this invention employs a high-Q, all-pass microring made of high-refractive-index-difference-doped glass, with a Q value ranging from 2 × 10⁻⁶. 6 ~ 3×10 6The spectral range generated by the microring resonator is 1500 nm to 1600 nm. As shown in Figure 2, the chaotic microring optical frequency comb is a broadband light source composed of a series of discrete, equally spaced modes, with adjacent modes spaced approximately 0.4 nm apart. The free spectral range of the generated chaotic optical frequency comb can be changed by altering the radius of the microring resonator. The arrayed waveguide grating described in this invention is made of silicon nitride material, has 16 channels, and a channel spacing of 200 GHz.

[0026] In practical implementation, we use 10 chaotic micro-ring optical frequency combs to generate multiple broadband white noise channels. The output wavelength of the semiconductor lasers is 1553 nm. By designing the radius of the micro-ring resonator, the free spectral ranges of the ten chaotic micro-ring optical frequency combs increase sequentially: 41 GHz, 42 GHz, ..., 50 GHz. The 10 chaotic micro-ring optical frequency combs with different free spectral ranges are converged into a single waveguide and then demultiplexed into 16 signals by an arrayed waveguide grating. The channel bandwidth of the arrayed waveguide grating is 100 GHz. Taking one channel as an example, the channel contains 10 modes, with a center frequency interval of 5 GHz between each mode, as shown in Figure 3. Beat frequencies between modes generate white noise at corresponding center frequencies. The center frequencies of the white noise frequency band generated by these mode beat frequencies are f1, f2, ..., f... 10 These frequency bands are spliced ​​together at 10 GHz, 20 GHz, ..., 100 GHz respectively, and the final output is white noise with a bandwidth of about 100 GHz. The power spectrum is shown in Figure 4.

[0027] It is worth noting that the on-chip multi-channel broadband white noise generation method based on chaotic micro-ring optical frequency combs disclosed in this invention combines multi-channel chaotic micro-ring optical frequency combs with wavelength division multiplexing (WDM) technology to generate multi-channel broadband white noise signals. This invention introduces a chaotic micro-ring optical frequency comb and integrates a micro-ring resonator, a semiconductor laser, a waveguide array grating, and a photodetector onto a chip, resulting in a compact, highly integrated, and small-sized on-chip multi-channel white noise source. By increasing the channel bandwidth of the arrayed waveguide grating, the number of modes in the channel can be increased. The increased beat frequency interaction of more modes can significantly improve the bandwidth for generating white noise, exhibiting bandwidth scalability. Unlike existing technologies, its structure is relatively simple and highly stable, meeting the current application requirements for high bandwidth and parallelization.

[0028] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for generating multi-channel broadband white noise based on a chaotic micro-ring optical frequency comb, comprising 10 semiconductor lasers (2) with the same center wavelength, a micro-ring resonator (3) with the same number of semiconductor lasers (2), a waveguide array grating (5), and a photodetector array (6); wherein, The semiconductor laser (2), micro-ring resonator (3), waveguide array grating (5), and photodetector array (6) are all integrated on the same chip substrate 1, and the devices are connected by optical waveguides (4); the continuous light output from the semiconductor laser (2) is injected into the micro-ring resonator (3) after being transmitted through the optical waveguide; the center wavelength of the laser output from the semiconductor laser is located at the blue detuning point of the resonant peak of the micro-ring resonator, that is, the pump wavelength is smaller than the wavelength corresponding to the resonant frequency closest to this pump wavelength; the linewidth of the laser output from the semiconductor laser is smaller than the linewidth of the resonant peak of the micro-ring resonator, and the combined effects of four-wave mixing, self-phase modulation, cross-phase modulation, stimulated Raman scattering, and dispersion will occur in the micro-ring resonator (3), resulting in a large broadening of the spectrum; a chaotic optical frequency comb with equal frequency spacing is output through the direct port of the micro-ring resonator (3); by designing the micro-ring resonator... The radius of the resonant cavity (3) is used to generate chaotic optical frequency combs with different free spectral ranges. The chaotic optical frequency combs generated by each micro-ring resonant cavity are coupled to a waveguide and then demultiplexed into n signals by the waveguide array grating (5). When using the waveguide array grating for wave demultiplexing, the channel bandwidth of the waveguide array grating should be much larger than the linewidth of a single comb tooth of the chaotic optical frequency comb. Each channel must contain multiple spectral modes. The n high-bandwidth white noises are obtained through the photodetector array (6), where n ≥ 2. The bandwidth of each white noise generated is related to the channel bandwidth of the waveguide array grating. Under the beat frequency action of multiple different detuned spectral modes, the spectra generated after photoelectric conversion will be spliced ​​together in sequence to finally generate broadband white noise. By adjusting the channel bandwidth of the waveguide array grating, the bandwidth of the white noise can be greatly improved, and the spectral bandwidth of each white noise reaches 100 GHz.

2. The method for generating multi-channel broadband white noise based on a chaotic micro-ring optical frequency comb as described in claim 1, characterized in that: Its micro-ring resonator structure can be all-through, up-and-down channel, non-concentric circle, or racetrack type.

3. The method for generating multi-channel broadband white noise based on a chaotic micro-ring optical frequency comb as described in claim 1, characterized in that: The free spectral range of a chaotic optical frequency comb can be tuned by designing the radius of the microring resonator, and the free spectral range of the generated multiple chaotic optical frequency combs increases sequentially, while the frequency detuning between corresponding modes of the chaotic optical frequency comb gradually increases; the free spectral range of the chaotic microring optical frequency comb is calculated using the following formula: ;in, λ represents the free spectral range of the microring resonator, λ is the center wavelength of the laser output light, and n g Let be the group refractive index of the microring resonator waveguide, and L be the length of the microring resonator.

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