Programmable optical frequency comb light source based on dispersion reconfigurable microcavity

Abstract

The invention discloses a programmable optical frequency comb light source based on a dispersion reconfigurable microcavity, and the structure of the programmable optical frequency comb light source comprises a grating writing and dispersion detection module, an integrated microcavity module with a photoinduced refraction characteristic, an optical comb pumping and spectrum sensing module, and a feedback control and signal processing module. The working principle is as follows: on a micro-ring resonant cavity with a photorefractive effect, laser is written into a programmable Bragg grating, so that a dispersion curve of the micro-cavity is reconstructed in real time; then, an intelligent feedback closed loop is formed by monitoring the spectrum and repetition frequency of the output optical comb and comparing the spectrum and repetition frequency with a target set by a user, and the grating pattern is automatically adjusted until the output spectrum is matched with the target. The programmable optical frequency comb light source can be dynamically reconstructed or switched according to different application requirements. The programmable optical frequency comb can be used as a light source module of a co-packaging optical technology, bandwidth density is improved, power consumption is reduced, and therefore the programmable optical frequency comb can be widely applied to interconnection of next-generation data centers.

Description

Technical Field

[0001] This invention relates to the field of photonic integrated devices, and more particularly to a programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity. Background Technology

[0002] With the explosive growth in AI computing power demand, traditional pluggable optical modules are facing bottlenecks in bandwidth, power consumption, and density. Co-packaged optics (CPO) technology, by co-packaging the optical engine with the chip, shortens the electrical interconnect distance, increases bandwidth density, and reduces power consumption, becoming a key technology for next-generation data center interconnects. However, existing CPO solutions rely on laser arrays, which present challenges in terms of wavelength quantity, stability, and accuracy expansion. Chip-scale multi-wavelength lasers, which can generate multiple uniformly spaced and phase-locked wavelengths from a single device, have become a potential solution to these problems. Currently, the main technical routes for realizing on-chip multi-wavelength light sources include distributed feedback (DFB) laser arrays and quantum dot mode-locked lasers. However, DFB laser arrays suffer from poor wavelength spacing stability and inconsistent noise characteristics among channels; while quantum dot mode-locked lasers can provide stable frequency spacing, their phase noise is usually high, making it difficult to achieve extremely narrow linewidths. Kerr optical frequency comb (microcavity optical comb) technology based on optical microcavities generates numerous broadband, equally spaced and phase-coherent comb teeth in a nonlinear micro-resonant cavity through a single pump light source. It has the significant advantages of high integration, extremely stable wavelength (frequency) spacing, and narrow linewidth of individual comb teeth, and is regarded as a next-generation integrated multi-wavelength light source solution with great development potential.

[0003] A fundamental bottleneck in existing microcavity optical comb technology lies in the fact that its core dispersion characteristics are fixed after device design and fabrication. This directly leads to limited functionality, locked performance, and a lack of intelligent adaptability. Specifically, a fabricated microcavity can only support one spectral pattern and cannot be dynamically reconstructed or switched according to different application requirements. Its final performance is determined after device fabrication, and there is a lack of effective post-processing correction and optimization capabilities for performance degradation or deviations from optimal values ​​caused by process deviations or environmental disturbances. Summary of the Invention

[0004] In view of this, in order to solve the technical problem that existing microcavity optical combs can only support one spectral pattern after fabrication, thus making it impossible to dynamically reconstruct or switch according to different application requirements, this invention proposes a programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity. Its structure includes: a grating writing and dispersion detection module, an integrated microcavity module with photorefractive properties, an optical comb pumping and spectral sensing module, and a feedback control and signal processing module. Its working principle is as follows: a programmable Bragg grating is written on a micro-ring resonant cavity with photorefractive effect using laser, thereby reconstructing the dispersion curve of the microcavity in real time; then, by monitoring the spectrum and repetition rate of the output optical comb and comparing it with the target set by the user, an intelligent feedback closed loop is formed, automatically adjusting the grating pattern until the output spectrum matches the target.

[0005] Based on the above scheme, this invention provides a programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity. Its beneficial effects include: 1) Flexible and reconfigurable function: Breaking through the traditional paradigm of "one device, one function," it achieves the ability to "customize the spectrum" on the integrated optical comb. Users can dynamically switch the same device between soliton combs, flat combs, and even arbitrary custom spectral forms via commands, enabling a single chip to adaptively cover various application scenarios such as communication, metrology, and spectroscopy, greatly improving the versatility of the device and the system integration. 2) Enhanced manufacturing value and promotion of paradigm innovation: It allows for post-processing correction of non-ideal devices caused by process deviations, reducing the dependence on the extreme uniformity of the fabrication process, resulting in significant economic benefits. More importantly, it transforms the optical frequency comb from a functionally fixed optical device into a "smart optical processor" that can be programmed in real time, providing a core engine for building the next generation of adaptive, reconfigurable photonic information systems. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the intelligent optical frequency comb light source based on a dispersion-reconfigurable microcavity according to the present invention; Figure 2 This is a flowchart illustrating a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the dispersion and mode splitting distribution obtained by the feedback control and signal processing module in this invention; Figure 4 This is a schematic diagram of the experimental results of the flat optical comb in the embodiments of the present invention; Figure reference numerals: 10, Grating writing and dispersion detection module; 20, Optical comb pumping and spectral sensing module; 30, Integrated microcavity module with photorefractive properties; 40, Feedback control and signal processing module; 101, Grating writing laser; 102, Tunable laser; 103, First optical switch; 104, Second optical switch; 105, Power meter; 106, Data acquisition unit; 201, Pump laser; 202, Optical coupler; 203, Spectrum analyzer; 204, Repetition rate testing module. Detailed Implementation

[0007] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0008] It should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0009] It should be understood that the terms "system," "apparatus," "unit," and / or "module" used in this application are a method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0010] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "a," and / or "the" are not specifically singular and may include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0011] In the description of the embodiments of this application, "a plurality of" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0012] Furthermore, flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, the steps can be processed in reverse order or simultaneously. Additionally, other operations can be added to these processes, or one or more steps can be removed from them.

[0013] Reference Figure 1 This is a schematic diagram of an optional example of the programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity proposed in this invention. The programmable optical frequency comb light source proposed in this embodiment may include, but is not limited to, the following modules: an integrated microcavity module 30 with photorefractive properties, a built-in grating writing and dispersion detection module 10, an optical comb pumping and spectral sensing module 20, and a feedback control and signal processing module 40. Each module is connected by optical fiber and electrical connections to form a complete intelligent closed loop, wherein: The integrated microcavity module 30 with photorefractive properties is the core functional carrier of the system. It is usually made of a material with photorefractive refractive index change characteristics. Its internal refractive index distribution can be non-volatilely modulated by an external light field, thereby realizing dynamic programming of dispersion characteristics.

[0014] The grating writing and dispersion detection module 10 is used to perform dispersion programming and characterization on the integrated microcavity module 30 with photorefractive properties. Its input end includes a high-power grating writing laser 101 and a broadband continuously tunable laser 102, and a first optical switch 103 switches to select the light source injected into the microcavity. Its output end includes a power meter 105 and a data acquisition unit 106, and a second optical switch 104 switches to guide the microcavity output to the corresponding detector. When the first optical switch 103 switches to the grating writing laser 101 and the second optical switch 104 switches to the power meter 105, the system enters the "grating writing and erasing" mode. The feedback control module 40 adjusts the grating writing laser frequency to stabilize the intracavity power, completing the precise writing or erasing of the grating. When the first optical switch 103 switches to the broadband tunable laser 102 and the second optical switch 104 switches to the data acquisition unit 106, the system enters the "dispersion test" mode. By scanning and probing the laser wavelength and recording the transmission spectrum, the real-time dispersion distribution of the microcavity is analyzed by the feedback control and signal processing module 40.

[0015] The optical comb pumping and spectral sensing module 20 is used to excite the optical comb and monitor its output characteristics. Its input is connected to a pump laser 201, which injects continuous pump light into a programmed integrated microcavity module 30 with photorefractive properties to generate an optical frequency comb. Its output is split into two paths via an optical coupler 202: one path is connected to a spectral analyzer 203 for real-time measurement of the spectral shape of the output optical comb; the other path is connected to a repetition rate testing module 204 for detecting the repetition frequency signal of the optical comb. The spectral shape and repetition rate information are synchronously transmitted to the feedback control and signal processing module 40.

[0016] The feedback control and signal processing module 40, as the intelligent control core of the system, is typically implemented based on an embedded computer or a high-performance processor, and runs the core control algorithm. This module receives the target spectrum and related parameters set by the user through a software interface, and receives dispersion data from the grating writing and dispersion detection module 10 and spectral and repetition rate data from the optical comb pump and spectral sensing module 0. It then executes actions such as... Figure 2 The closed-loop workflow shown enables intelligent control of the entire system.

[0017] The specific workflow of this invention is as follows, and its logical correspondence is as follows: Figure 2 The flowchart shown is as follows: 1) Target Input and Intelligent Decision-Making: The user sets the target spectrum (e.g., a flat spectrum) to the feedback control and signal processing module 40 through the software interface, and can also input basic parameters of the microcavity, such as the free spectral range, dispersion coefficient, and quality factor. The feedback control and signal processing module 40 calls the built-in AI model to calculate the "target dispersion and splitting distribution" required to achieve this spectrum based on the target spectrum and parameters. The AI ​​model is a trained deep neural network (encoder-decoder structure), which receives the user-set target spectrum and initial microcavity parameters as input. Through embedded physical constraints and data-driven mapping, it directly solves inversely for the grating writing parameters (including the wavelength of the writing laser, the target splitting distribution, and the dispersion curve) required to achieve the target. This model is trained using a simulation-generated dataset and can be fine-tuned online based on the spectral measurement results after writing, achieving precise and adaptive programming of the comb spectral shape.

[0018] 2) Dispersion Reconstruction and Verification Closed Loop: The feedback control and signal processing module 40 drives the grating writing and dispersion detection module 10 to perform "grating writing and erasing" operations according to the calculated target dispersion parameters, reconstructing the dispersion in the integrated microcavity module 30 with photorefractive properties. The specific physical mechanism of this operation is as follows: a high-power grating writing laser is injected into the microcavity to form a standing wave field within the cavity. At the antinodes of the standing wave, the refractive index of the material is locally and stably reduced through the photorefractive effect, thereby periodically modulating the refractive index, i.e., writing a Bragg grating. When the grating refractive index contrast reaches a threshold, it will cause the microring resonance mode to split. Continuing to inject grating writing laser into a split resonance peak can further enhance the grating contrast at that point; while the erasing operation is achieved by injecting grating writing laser into another split resonance peak. At this time, the second set of gratings written coherently cancels out the original grating space, thereby reducing the overall refractive index modulation depth, which is equivalent to "erasing" or weakening the existing grating. Reversible programming of grating contrast and mode splitting can be achieved by controlling the lasers written to different resonance peaks.

[0019] Subsequently, the grating writing and dispersion detection module 10 switches to "dispersion test" mode to measure the actual dispersion of the programmed microcavity. The feedback control and signal processing module 40 compares the measured actual dispersion with the "target dispersion". If the difference does not meet the preset tolerance, it returns to this step and adjusts the grating writing parameters iteratively; if it meets the tolerance, it proceeds to the next step.

[0020] 3) Optical Comb Excitation and Spectral Verification Closed Loop: The feedback control and signal processing module 40 controls the optical comb pumping and spectral sensing module 20 to start the pump laser 201, pumping the integrated microcavity module 30 with photorefractive properties whose dispersion meets the requirements, thus generating an optical frequency comb. The optical comb pumping and spectral sensing module 20 simultaneously monitors the "spectral shape and repetition rate" of the generated optical comb and feeds the data back to the feedback control and signal processing module 40. The feedback control and signal processing module 40 compares the measured "spectral shape" with the "target spectrum" set by the user. If the difference does not meet the preset tolerance, the feedback control system will determine that the difference is due to a change in dispersion during the optical comb excitation process, which still needs optimization. The process returns to step 1, where the AI ​​model recalculates and updates the target dispersion, initiating a new round of dispersion programming closed loop. If the difference between the measured spectrum and the target spectrum meets the requirements, the system determines that convergence has occurred.

[0021] 4) Output and Locking: After the system passes the above dual closed-loop verification, the feedback control and signal processing module 40 will lock the current pump laser state, and the system will stably output an optical frequency comb that meets the user's set target.

[0022] Figure 3This diagram illustrates a specific example of generating a flat optical comb using the method proposed in this invention. Taking the generation of a flat optical comb as an example, the diagram demonstrates the complete process from a preset target spectrum to solving for key physical parameters: after inputting the target spectral morphology and initial microcavity parameters into the system, optimization calculations are performed via a built-in intelligent processing algorithm, ultimately outputting the target dispersion curve and corresponding mode resonance distribution of the microcavity required to achieve the target spectrum. This diagram aims to exemplify the implementation path and parameter mapping relationship of the method of this invention.

[0023] Figure 4 This is a schematic diagram of the results obtained from the actual experiment using the method described above. The experiment successfully generated a flat optical comb covering the 1540 nm to 1600 nm wavelength band, with a spectral flatness within ±1.5 dB. This experimental result directly verifies that the method of this invention can effectively control the output characteristics of the optical comb according to a preset target, and achieve high-performance spectral output in actual devices.

[0024] This invention provides an intelligent programmable microcavity optical frequency comb based on real-time feedback and dispersion programming, solving the core problem of traditional microcavity optical frequency combs having fixed output spectral characteristics and being unable to be dynamically reconfigured on demand. By introducing intelligent closed-loop control of "sensing-decision-execution," this system upgrades the microcavity optical frequency comb from a device with fixed functions to an intelligent optical comb light source whose output spectrum can be dynamically defined by software. The frequency spacing and spectral shape of this intelligent optical comb are tunable, enabling dense wavelength division multiplexing (DWDM) technology in co-packaged optical modules, significantly increasing the transmission capacity of a single optical fiber, and meeting the high bandwidth requirements of CPO (Content Processing) applications.

[0025] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A programmable optical frequency comb light source based on a dispersive reconfigurable microcavity, characterized in that, include: An integrated microcavity module with photorefractive properties has its internal refractive index distribution non-volatilely modulated by an external optical field; A grating writing and dispersion detection module is used to perform dispersion programming and characterization on the integrated microcavity module; An optical comb pump and spectral sensing module is used to excite the optical comb and monitor its output characteristics; The feedback control and signal processing module responds to user input, receives data from the grating writing and dispersion detection module and data from the optical comb pump and spectrum sensing module, and regulates the programmable optical frequency comb light source.

2. The programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity according to claim 1, characterized in that, The grating writing and dispersion detection module specifically includes: Write-grid lasers and tunable lasers; The first optical switch is used to switch between the input writing laser and the detection laser; The second optical switch is used to switch the output. A power meter is used to detect output power; A data acquisition unit is used to acquire microcavity transmission spectra.

3. The programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity according to claim 2, characterized in that, The specific working process of the grating writing and dispersion detection module is as follows: The light source injected into the microcavity is selected by switching the first optical switch; The microcavity output is guided to the corresponding detector by switching via the second optical switch; When the first optical switch is switched to the grating laser and the second optical switch is switched to the power timer, the system enters the "grating writing and erasing" mode. The grating laser frequency is adjusted through the feedback control and signal processing module to complete the precise writing or erasing of the grating. When the first optical switch is switched to the tunable laser and the second optical switch is switched to the data acquisition unit, the system enters the "dispersion test" mode. By scanning and probing the laser wavelength and recording the transmission spectrum, the real-time dispersion distribution of the microcavity is obtained by the feedback control and signal processing module.

4. The programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity according to claim 1, characterized in that, The microcavities in the integrated microcavity module with photorefractive properties are made of materials including, but not limited to, any one of arsenic sulfide, arsenic selenide, germanium arsenic selenium, germanium arsenic sulfide, germanium tellurium selenium, germanium tellurium sulfide, arsenic sulfide selenium, lithium niobate, and lithium tantalate.

5. The programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity according to claim 1, characterized in that, The optical comb pumping and spectral sensing module includes a pump laser at the input end and an optical coupler at the output end. The output of the optical comb pumping and spectral sensing module includes two parts, wherein: A portion of the output is input to a spectrometer to test the shape of the output optical comb spectrum; Another portion of the output is used to test the optical comb repetition rate.

6. The programmable optical frequency comb light source based on a dispersive reconfigurable microcavity according to claim 1, characterized in that, The specific working process of the feedback control and signal processing module is as follows: Receive the target spectrum from user input; The actual spectrum monitored by the spectral sensing module is acquired in real time, and the difference between the actual spectrum and the target spectrum is calculated. Based on the difference, identify the comb teeth whose matching degree exceeds the set value, retest the microcavity dispersion and calculate the grating writing mode splitting amount required to compensate for the difference, and obtain the grating writing control parameters. The grating writing control parameters are sent to the grating writing and dispersion detection module to perform dispersion reconstruction.

7. The programmable optical frequency comb light source based on a dispersion-reconfigurable microcavity according to claim 6, characterized in that, Also includes: The process includes a cyclic difference calculation step, a control parameter calculation step, and a dispersion reconstruction step. When the difference is less than a set threshold, the output is locked.

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