Arc optical frequency comb device, system and communication equipment

Abstract

The invention discloses an arc optical frequency comb device and system and communication equipment, and relates to the technical field of optical communication. According to the device, active or passive functional devices such as a wavelength division multiplexer, a gain waveguide, a microcavity structure, a delay tuning unit, a beam splitter and the like are all integrated on the same silicon nitride chip to form an on-chip laser resonant cavity, and the coupling alignment error of a discrete optical fiber and a spatial optical path is eliminated. The gain waveguide provides optical power amplification, and the microcavity structure forms a soliton state optical frequency comb based on a Kerr nonlinear effect; the delay tuning unit adjusts the detuning amount between the main cavity and the microcavity in real time by introducing accurate light delay, so that rapid excitation and stable locking of the soliton state optical frequency comb are realized, and traditional mechanical tuning is replaced. The beam splitter feeds back part of light to maintain oscillation, and the other part of light is output as a low-noise soliton optical frequency comb. The above structure solves the problems of large size, complex adjustment and poor stability of the existing system through the cooperation of all-on-chip integration and tuning and detuning.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and in particular to an arc optical frequency comb device, system and communication equipment. Background Technology

[0002] Laser cavity soliton microcombs based on the nonlinear Kerr effect typically involve injecting a pump laser into a microring resonant cavity with a high quality factor. Under conditions of dispersion and nonlinearity balance, multiple phase-locked comb teeth are generated using modulation instabilities and four-wave mixing effects. However, these techniques usually rely on discrete fiber optics to construct the gain main cavity and depend on free-space coupling and mechanical delay lines for cavity length adjustment. This results in a large system size, complex structure, poor stability, and difficulty in achieving fast and precise soliton state control and stable maintenance, severely hindering its practical application. Summary of the Invention

[0003] The main objective of this application is to provide an arc-type optical frequency comb device, system, and communication equipment, aiming to solve the technical problems of how to improve the stability, control speed, and conversion efficiency of the optical frequency comb.

[0004] To achieve the above objectives, embodiments of this application provide an arc-shaped optical frequency comb device, the arc-shaped optical frequency comb device comprising: Silicon nitride chip; A laser resonant cavity integrated on the silicon nitride chip, the laser resonant cavity comprising: A wavelength division multiplexer is used to couple a first wavelength light provided by a pump source and a second wavelength light provided by a beam splitter to form a preset composite light, and inject the preset composite light into a gain waveguide; The gain waveguide is used to provide optical power gain for the preset synthesized light and to provide the amplified preset synthesized light to the microcavity structure; The microcavity structure is used to form an arc state optical frequency comb with a preset phase based on the preset synthesized light through the Kerr nonlinear effect and transmit it to the delay tuning unit. The delay tuning unit is used to receive and output the arc state optical frequency comb, and at the same time adjust the detuning between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure by introducing a preset optical delay amount, so as to maintain the arc state optical frequency comb. The beam splitter is used to split the arc state optical frequency comb provided by the delay tuning unit into beams at a preset ratio, feed a portion of it back to the wavelength division multiplexer as the second wavelength light, and output the other portion.

[0005] In one embodiment, the delay tuning unit includes: an optical delay line and a micro heating element; The micro heating element is integrated on the optical delay line; The micro heating element is used to adjust the refractive index of the optical delay line based on the thermo-optical effect to introduce the preset optical delay amount, so as to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure in conjunction with the optical delay line.

[0006] In one embodiment, the delay tuning unit includes: an optical delay line and a carrier injection structure; The carrier injection structure is integrated on the optical delay line; The carrier injection structure is used to adjust the refractive index of the optical delay line based on the carrier dispersion effect to introduce the preset optical delay amount, so as to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure in conjunction with the optical delay line.

[0007] In one embodiment, the delay tuning unit includes: an optical delay line and a piezoelectric driver; The piezoelectric driver is integrated into the optical delay line; The piezoelectric actuator is used to adjust the refractive index of the optical delay line based on the photoelastic effect to introduce the preset optical delay amount, so as to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure in conjunction with the optical delay line.

[0008] In one embodiment, the optical delay line adopts either a helical waveguide structure or a multi-level ring waveguide structure.

[0009] In one embodiment, the microcavity structure is either a microring resonator or an FP cavity.

[0010] In one embodiment, the laser resonant cavity further includes a filter; The filter is disposed in the optical path between the delay tuning unit and the beam splitter; The filter is used to filter out non-target wavelength light other than the arc state optical frequency comb; The filter can be either a micro-ring filter or an MZI filter.

[0011] In one embodiment, the laser resonant cavity further includes: an isolator; The isolator is disposed in the optical path between the delay tuning unit and the beam splitter; The isolator is used to ensure that the arc state optical frequency comb is transmitted unidirectionally from the delay tuning unit to the beam splitter.

[0012] In addition, this application also proposes an arc-shaped optical frequency comb system, which adopts the arc-shaped optical frequency comb device as described above.

[0013] In addition, this application also proposes a communication device that employs the arc optical frequency comb system described above.

[0014] This application provides an arc-shaped optical frequency comb device, system, and communication equipment. The arc-shaped optical frequency comb device includes: a silicon nitride chip; and a laser resonant cavity integrated on the silicon nitride chip. The laser resonant cavity includes: a wavelength division multiplexer for coupling a first wavelength light provided by a pump source and a second wavelength light provided by a beam splitter to form a preset composite light, and injecting the preset composite light into a gain waveguide; the gain waveguide for providing optical power gain to the preset composite light, and providing the amplified preset composite light to a microcavity structure; the microcavity structure for... A preset synthesized light is used to form an arc-state optical frequency comb with a preset phase through the Kerr nonlinear effect and transmitted to a delay tuning unit. The delay tuning unit is used to receive and output the arc-state optical frequency comb, and at the same time, it adjusts the detuning between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure by introducing a preset optical delay, so as to maintain the arc-state optical frequency comb. The beam splitter is used to split the arc-state optical frequency comb provided by the delay tuning unit into beams at a preset ratio, feeding a portion as the second wavelength light back to the wavelength division multiplexer, and outputting the other portion.

[0015] By integrating all active or passive functional devices, such as wavelength division multiplexers, gain waveguides, microcavity structures, delay tuning units, and beam splitters, onto a single silicon nitride chip, an on-chip laser resonant cavity is constructed, eliminating alignment errors caused by coupling discrete optical fibers with the spatial optical path. The gain waveguide provides optical power amplification, and the microcavity structure forms a soliton optical frequency comb based on the Kerr nonlinear effect. The delay tuning unit introduces precise optical delay to adjust the detuning between the main cavity and the microcavity in real time, thereby achieving rapid excitation and stable locking of the soliton optical frequency comb, replacing traditional mechanical tuning. The beam splitter maintains oscillation through partial optical feedback, while the remaining output is a low-noise soliton optical frequency comb. This structure, through full on-chip integration and synergistic detuning, solves the problems of large size, complex adjustment, and poor stability in existing systems. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1This is a structural schematic diagram of Embodiment 1 of the arc-shaped optical frequency comb device of this application; Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the arc-shaped optical frequency comb device of this application; Figure 3 This is a schematic diagram of a microcavity structure proposed in this application; Figure 4 This is another schematic diagram of the microcavity structure proposed in this application.

[0019] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0021] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0022] This application presents a first embodiment of the arc-shaped optical frequency comb device; please refer to [link / reference]. Figure 1 The arc-shaped optical frequency comb device includes: Silicon nitride chip 109; The laser resonant cavity integrated on the silicon nitride chip 109 includes: The wavelength division multiplexer 101 is used to couple the first wavelength light provided by the pump light source and the second wavelength light provided by the beam splitter 108 to form a preset composite light, and inject the preset composite light into the gain waveguide 102. The gain waveguide 102 is used to provide optical power gain for the preset synthesized light and to provide the amplified preset synthesized light to the microcavity structure 103. The microcavity structure 103 is used to form an arc state optical frequency comb with a preset phase based on the preset synthesized light through the Kerr nonlinear effect and transmit it to the delay tuning unit 104. The delay tuning unit 104 is used to receive and output the arc state optical frequency comb, and at the same time adjust the detuning between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103 by introducing a preset optical delay amount, so as to maintain the arc state optical frequency comb. The beam splitter 108 is used to split the arc state optical frequency comb provided by the delay tuning unit 104 into beams at a preset ratio, feed a portion of it back to the wavelength division multiplexer 101 as the second wavelength light, and output the other portion.

[0023] It should be understood that silicon nitride chip 109 refers to a monolithic photonic integrated circuit substrate using silicon nitride (SiN) as the core optical waveguide material. A laser resonant cavity is an optical structure that enables light to circulate and resonate within it, and compensates for losses through a gain medium to generate and maintain laser light.

[0024] It should be noted that silicon nitride exhibits extremely high transparency across a wide wavelength range from visible light to mid-infrared, thus allowing the fabrication of waveguide structures with smooth sidewalls, extremely low scattering loss, and extremely high Q values ​​based on silicon nitride substrates. Furthermore, because silicon nitride has a significantly higher nonlinear refractive index than silicon dioxide but much lower, it can generate sufficiently strong nonlinear effects in the communication band while avoiding the severe two-photon absorption effect, free carrier absorption loss, and temperature instability caused by traditional silicon materials in the 1550nm band. In this embodiment, the optical devices described above, such as the wavelength division multiplexer 101, gain waveguide 102, microcavity structure 103, delay tuning unit 104, and beam splitter 108, are integrated onto a silicon nitride chip 109. These components are directly optically interconnected through etched silicon nitride waveguides, forming a laser resonant cavity. Based on the above design, the laser resonant cavity exhibits low loss, high Q value, and high cycling efficiency, enabling high-speed and efficient cyclic resonance of light. Transmission loss is compensated and optical transmission is maintained through the gain medium provided within the gain waveguide 102. This fully on-chip integrated solution directly eliminates the fusion splices of discrete fiber optic devices and the free-space coupling interface between the chip and the fiber, as in traditional solutions. This avoids coupling efficiency fluctuations and system instability caused by the sensitivity of these interfaces to environmental vibrations and temperature drift. Simultaneously, integration significantly reduces the system size, laying the foundation for device miniaturization and practical application.

[0025] It should be understood that, in this embodiment, the first wavelength light refers to a pump light of a specific wavelength generated by the pump light source, while the second wavelength light refers to the feedback light or probe light composed of multiple equally spaced wavelengths fed back by the beam splitter 108, which can also be understood as the optical frequency comb itself ultimately output by the laser resonant cavity.

[0026] It should be noted that, in this embodiment, the preset synthesized light specifically refers to the optical signal formed by combining the pump light (first wavelength light) and the feedback light (second wavelength light) from the beam splitter 108 in the wavelength division multiplexer 101. This optical signal is subsequently injected into the gain waveguide 102. The preset phase does not refer to a specific externally preset phase value, but rather to the defined phase-locked relationship between the teeth of the arc state optical frequency comb formed when the preset synthesized light circulating in the laser resonant cavity reaches a soliton steady state. The preset optical delay refers to the adjustable optical delay introduced by the delay tuning unit 104 to achieve resonant frequency matching between the main cavity and the microcavity of the laser resonant cavity.

[0027] It should be noted that, in this embodiment, the gain waveguide 102 is a waveguide structure in which a gain medium is formed in a silicon nitride waveguide using techniques such as ion implantation, enabling it to provide optical power amplification under pump light (first wavelength light) excitation. As a preferred embodiment, an erbium-doped integrated waveguide can be designed using multiple concentric ring structures or structures including grating couplers and mode transition waveguides, as the gain waveguide 102 proposed in this embodiment.

[0028] As is easily understood, the gain waveguide 102, together with the wavelength division multiplexer 101 and beam splitter 108, forms a closed optical loop with net gain. This loop provides the necessary optical power compensation for the circulating optical signal within the entire laser resonant cavity, enabling the generation and maintenance of laser oscillation. This structure replaces the discrete fiber amplifier in traditional external cavity schemes, simplifying the overall structure of the device and reducing coupling loss through on-chip integration. This improves the conversion efficiency from pump light to signal light, thereby contributing to increased output power and system energy efficiency of the soliton frequency comb.

[0029] It should be noted that, in this embodiment, the microcavity structure 103 refers to an on-chip optical microresonator with a high quality factor (high Q value), which is the core device for generating the Kerr nonlinear effect. The Kerr nonlinear effect refers to a nonlinear optical effect in which the change in refractive index caused by the light field in a medium is proportional to the light intensity.

[0030] It is easy to understand that the microcavity structure 103 enhances the cyclic optical field based on its high Q-value characteristics. When the optical signal from the gain waveguide 102 (i.e., the laser beam after multiple amplifications of the pre-synthesized light in the loop) couples into the microcavity structure 103 and reaches a certain power threshold, the strong optical field generates new frequency components through Kerr nonlinear effects (such as four-wave mixing). Under specific conditions of dispersion and nonlinearity balance, these frequency components evolve and lock into a series of phase-coherent frequency combs, i.e., soliton-state optical frequency combs. The technical advantage of the microcavity structure is that it provides the strong nonlinear interactions and fine mode selection capabilities necessary for generating broadband, low-noise optical frequency combs.

[0031] It should be noted that, in this embodiment, the delay tuning unit 104 is a functional module for achieving precise and rapid electrical tuning of the optical path length (or equivalent phase). It can introduce controllable optical delay (i.e., change the preset optical delay amount) to adjust the offset between the resonant frequency of the laser resonant cavity and the resonant frequency of the microcavity structure 103 (i.e., the above-mentioned detuning amount) to precisely adjust the optical length of the entire laser resonant cavity.

[0032] It is easy to understand that since the resonant frequency of a laser resonator is determined by its optical length, adjusting the delay can be equivalent to continuously adjusting the resonant frequency of the laser resonator. In this embodiment, the detuning between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103 is adjusted by the delay tuning unit 104, thereby achieving rapid excitation, selection, and stable locking of soliton states. Compared with methods that rely on slow and imprecise mechanical delays for cavity length adjustment, this method greatly improves the speed, accuracy, and reliability of control, and solves the problems of complex control and difficulty in achieving rapid and precise control in existing technologies.

[0033] It should be noted that, in this embodiment, the beam splitter 108 is an on-chip optical coupling device with a specific splitting ratio (i.e., the aforementioned preset ratio), used to split the energy of one input light into two output lights according to a preset ratio. As a specific method, the preset ratio can be 90:10, and the output light with 1 / 10 power can be used as feedback light to be transmitted back to the wavelength division multiplexer 101.

[0034] As is readily understood, in this embodiment, one output beam of beam splitter 108 (the lower-power beam) is returned to wavelength division multiplexer 101 as feedback light (i.e., the second wavelength light) and re-injected into gain waveguide 102, forming the optical feedback loop necessary to maintain laser oscillation. The other output beam serves as an effective soliton frequency comb signal for external system use. In one scenario, the laser output to the outside can be measured using a spectrometer and oscilloscope, with the pulse width measured using an autocorrelation meter. The linewidth, frequency noise, and phase noise are analyzed using a laser linewidth measurement system to optimize optical communication parameters.

[0035] This application proposes an arc-state optical frequency comb device, comprising a silicon nitride chip and integrated on the silicon nitride chip a wavelength division multiplexer, a gain waveguide, a microcavity structure, a delay tuning unit, and a beam splitter. By integrating all active or passive functional devices such as the wavelength division multiplexer, gain waveguide, microcavity structure, delay tuning unit, and beam splitter onto the same silicon nitride chip, an on-chip laser resonant cavity is formed, eliminating the coupling alignment error between discrete optical fibers and spatial optical paths. The gain waveguide provides optical power amplification, and the microcavity structure forms a soliton optical frequency comb based on the Kerr nonlinear effect. The delay tuning unit introduces precise optical delay to adjust the detuning between the main cavity and the microcavity in real time, thereby achieving rapid excitation and stable locking of the soliton optical frequency comb, replacing traditional mechanical tuning. The beam splitter maintains oscillation with part of the optical feedback, and outputs a low-noise soliton optical frequency comb. The above structure, through the synergy of on-chip integration and detuning, solves the problems of large size, complex adjustment, and poor stability of existing systems.

[0036] Based on the first embodiment of the arc optical frequency comb device of this application, in the second embodiment of the arc optical frequency comb device of this application, the contents that are the same as or similar to those in the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 2 , Figure 3 as well as Figure 4 In this embodiment, the delay tuning unit 104 includes: an optical delay line 1041 and a micro heating element 1051; The micro heating element 1051 is integrated on the optical delay line 1041; The micro heating element 1051 is used to adjust the refractive index of the optical delay line 1041 based on the thermo-optical effect to introduce the preset optical delay amount, so as to cooperate with the optical delay line 1041 to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103.

[0037] It should be noted that, in this embodiment, the optical delay line 1041 is a waveguide structure designed to provide a longer optical path. The micro heating element 1051 refers to a micro resistive element integrated into the optical delay line 1041. The photothermal effect refers to the physical effect of the waveguide material's refractive index changing with temperature.

[0038] It is readily understood that in this embodiment, a current can be applied to the micro-heating element 1051 to generate heat, which is then conducted to the optical delay line 1041, raising its temperature. Based on the thermo-optical effect of silicon nitride, the waveguide refractive index of the optical delay line 1041 increases accordingly. Since the physical length of the optical delay line 1041 is fixed, its increased refractive index leads to an increase in its optical length, thus introducing a preset optical delay amount, which in turn changes the overall optical length of the laser resonator. Ultimately, the detuning between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103 can be adjusted using the optical delay line 1041. Based on this structure, electrically controlled, mechanically motionless delay tuning can be achieved. Its response speed can reach the microsecond level, far faster than mechanical adjustment, and the control is continuous and precise, improving the ability to quickly lock onto and dynamically stabilize the soliton state optical frequency comb.

[0039] Furthermore, in this embodiment, the delay tuning unit 104 includes: an optical delay line 1041 and a carrier injection structure 1052; The carrier injection structure 1052 is integrated on the optical delay line 1041; The carrier injection structure 1052 is used to adjust the refractive index of the optical delay line 1041 based on the carrier dispersion effect to introduce the preset optical delay amount, so as to coordinate with the optical delay line 1041 to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103.

[0040] It should be noted that, in this embodiment, the carrier injection structure 1052 refers to structures such as PN junctions and PIN junctions fabricated in a semiconductor waveguide. The carrier dispersion effect refers to the effect of changes in the concentration of free carriers (electrons and holes) in a semiconductor causing a change in its refractive index.

[0041] It is readily understood that, in this embodiment, the carrier injection structure 1052 can be integrated onto the optical delay line 1041. By applying a bias voltage to the carrier injection structure 1052, free carriers can be injected into or depleted in the optical mode field region of the optical delay line 1041. The carrier dispersion effect caused by the change in carrier concentration can rapidly change the refractive index of the waveguide, thereby changing the optical length of the optical delay line 1041, and consequently changing the optical length of the entire laser resonator. Ultimately, the amount of detuning between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103 can be adjusted in conjunction with the optical delay line 1041. Based on the above structure, extremely high tuning speeds, reaching the nanosecond level, can also be achieved.

[0042] Furthermore, in this embodiment, the delay tuning unit 104 includes: an optical delay line 1041 and a piezoelectric driver 1053; The piezoelectric driver 1053 is integrated on the optical delay line 1041; The piezoelectric actuator 1053 is used to adjust the refractive index of the optical delay line 1041 based on the photoelastic effect to introduce the preset optical delay amount, so as to coordinate with the optical delay line 1041 to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103.

[0043] It should be noted that, in this embodiment, the piezoelectric actuator 1053 refers to a device made of piezoelectric material (such as aluminum nitride) that can produce mechanical deformation under voltage. The elasto-optic effect, on the other hand, refers to the physical effect where the refractive index of a material changes when subjected to mechanical stress.

[0044] It is readily understood that in this embodiment, the piezoelectric driver 1053 can be integrated onto the optical delay line 1041. By applying voltage to the piezoelectric driver 1053, the resulting micro-deformation applies mechanical stress to the optical delay line 1041. This applied mechanical stress induces an elasto-optic effect, causing a change in the waveguide refractive index, thereby altering the optical length of the optical delay line 1041 and consequently changing the optical length of the entire laser resonator. Ultimately, the detuning between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure 103 can be adjusted using the optical delay line 1041. Based on this structure, extremely high tuning speeds can be achieved with very low power consumption and almost no heat generation, avoiding the thermal crosstalk problems that may arise from thermal tuning.

[0045] Furthermore, in this embodiment, the optical delay line 1041 adopts either a helical waveguide structure or a multi-level ring waveguide structure.

[0046] It should be noted that, in this embodiment, the spiral waveguide structure is a design that achieves a long optical path within a limited chip area by arranging the waveguide in a spiral configuration. The multi-level ring waveguide structure refers to a compact structure that generates a large group delay by cascading multiple micro-ring resonators and utilizing their resonant phase response.

[0047] It is readily understood that, in this embodiment, the helical waveguide structure can provide broadband, low-dispersion delay. In contrast, the multi-stage ring waveguide structure can achieve extremely high equivalent delay within a very compact area, but with a relatively narrow bandwidth. This embodiment can employ at least one of these two designs to adapt to application scenarios with different area and bandwidth requirements.

[0048] Furthermore, in this embodiment, the microcavity structure 103 is either a microring resonator or an FP cavity.

[0049] It should be noted that the FP cavity is a type of Fabry-Perot cavity. Please refer to [reference needed]. Figure 3 as well as Figure 4 , Figure 3 This demonstrates an "upload-download" structure, which is a typical microring resonant cavity. Figure 4 An FP cavity was demonstrated.

[0050] It is worth noting that, in this embodiment, for Figure 3 In the demonstrated microring resonator, wavelength division multiplexer 101 is connected to the microring input port 1, and output port 2 is connected to the input of optical delay line 1041. Output port 1 is used to monitor the operating status of the laser resonator. The gain main cavity and microcavity in the device are connected through an optimized asymmetric waveguide coupling structure. By precisely controlling the coupling gap and coupling length, the microring and the straight waveguide containing input port 1 and output port 1 achieve a critical coupling state, while overcoupling is achieved between output port 2. Figure 4 The demonstrated FP cavity specifically consists of a central cavity, two adiabatic conical gratings on either side, and a conventional Bragg grating. The adiabatic conical gratings reduce coupling loss within the grating cavity. The two mirrors, also composed of Bragg gratings, provide wavelength-selective feedback, allowing only specific wavelengths of light to couple back into the waveguide, thereby enhancing the resonant mode. The resonant wavelength of the microcavity structure 103 is determined by the cavity length and the grating period. The resonant wavelength can be adjusted by changing the cavity length or the refractive index of the waveguide.

[0051] It is easy to understand that, in this embodiment, the microring resonator can utilize traveling wave resonance, possessing an extremely high quality factor and mature fabrication technology, making it a preferred choice for generating efficient nonlinear effects; while the FP cavity, based on standing wave resonance, can flexibly control its characteristics by designing the grating reflection spectrum and cavity length. Both of these structures can achieve high-quality factor resonance, providing conditions for Kerr nonlinear effects and soliton generation.

[0052] Furthermore, in this embodiment, the laser resonant cavity further includes: a filter 106; The filter 106 is disposed in the optical path between the delay tuning unit 104 and the beam splitter 108; The filter 106 is used to filter out non-target wavelength light other than the arc state optical frequency comb; The filter 106 is either a micro-ring filter or an MZI filter.

[0053] It should be understood that, in this embodiment, the MZI filter is a Mach–Zehnder interferometer (MZI) filter.

[0054] It should be noted that in this embodiment, filter 106 is mainly used to purify the spectrum of the soliton-state optical frequency comb, suppressing out-of-band noise and unwanted side modes. In practice, either a micro-ring filter or an MZI filter can be used. The micro-ring filter has a compact structure and steep filtering, while the MZI filter is flexible in design and has controllable bandwidth. Based on the above structure, the spectral purity and signal-to-noise ratio of the output soliton-state optical frequency comb can be improved.

[0055] Furthermore, in this embodiment, the laser resonant cavity further includes: an isolator 107; The isolator 107 is disposed in the optical path between the delay tuning unit 104 and the beam splitter 108; The isolator 107 is used to ensure that the arc state optical frequency comb is transmitted unidirectionally from the delay tuning unit 104 to the beam splitter 108.

[0056] It should be noted that, in this embodiment, the isolator 107 is an optical device that can realize unidirectional transmission of light based on non-reciprocal magneto-optical effect or nonlinear effect.

[0057] It is readily understood that, in this embodiment, the isolator 107 can be positioned on the input side of the beam splitter 108. This effectively suppresses back-reflected light in the optical path, preventing it from returning to the main cavity and microcavity of the laser resonator and interfering with the stable soliton state, thus avoiding unstable relaxation oscillations or parasitic modes. Based on the above structure, the operating stability of the laser resonator can be improved, ensuring the reliability and stability of the soliton state optical frequency comb output.

[0058] Furthermore, this application also proposes an arc-shaped optical frequency comb device, wherein the arc-shaped optical frequency comb device adopts the arc-shaped optical frequency comb device as described above.

[0059] Since the arc optical frequency comb device proposed in this application includes all the technical solutions of all embodiments of the arc optical frequency comb device described above, the arc optical frequency comb device proposed in this application also has all the beneficial effects brought by all embodiments of the arc optical frequency comb device described above, and will not be repeated here.

[0060] Furthermore, this application also proposes a communication device that employs the arc optical frequency comb system described above.

[0061] Since the communication device proposed in this application includes all the technical solutions of all embodiments of the arc optical frequency comb system described above, the communication device proposed in this application also has all the beneficial effects brought by all embodiments of the arc optical frequency comb system described above, and will not be repeated here.

[0062] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. An arc-sub-frequence comb device, characterized in that, The arc light frequency comb device comprises: a silicon nitride chip; a laser resonant cavity integrated on the silicon nitride chip, the laser resonant cavity comprising: a wavelength division multiplexer configured to couple first wavelength light provided by a pump light source and second wavelength light provided by a beam splitter to form preset synthesis light, and inject the preset synthesis light into a gain waveguide; the gain waveguide configured to provide optical power gain for the preset synthesis light, and provide the gain waveguide to a microcavity structure; the microcavity structure configured to form preset phase arc state light frequency comb through Kerr nonlinear effect based on the preset synthesis light, and transmit the preset phase arc state light frequency comb to a delay tuning unit; the delay tuning unit configured to receive and output the arc state light frequency comb, and adjust a detuning amount between a resonant frequency of the laser resonator and a resonant frequency of the microcavity structure by introducing a preset optical delay amount, so as to maintain the arc state light frequency comb; the beam splitter configured to split the arc state light frequency comb provided by the delay tuning unit at a preset ratio, feed back a part of the arc state light frequency comb as the second wavelength light to the wavelength division multiplexer, and output another part of the arc state light frequency comb.

2. The arc light frequency comb device of claim 1, wherein, The delay tuning unit comprises an optical delay line and a micro heating element. The micro heating element is integrated on the optical delay line. The micro heating element is configured to adjust the refractive index of the optical delay line based on thermo-optic effect to introduce the preset optical delay amount, so as to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure in cooperation with the optical delay line.

3. The arc light frequency comb device of claim 1, wherein, The delay tuning unit comprises an optical delay line and a carrier injection structure. The carrier injection structure is integrated on the optical delay line. The carrier injection structure is configured to adjust the refractive index of the optical delay line based on carrier dispersion effect to introduce the preset optical delay amount, so as to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure in cooperation with the optical delay line.

4. The arc light frequency comb device of claim 1, wherein, The delay tuning unit comprises an optical delay line and a piezoelectric driver. The piezoelectric driver is integrated on the optical delay line. The piezoelectric driver is configured to adjust the refractive index of the optical delay line based on photoelastic effect to introduce the preset optical delay amount, so as to adjust the detuning amount between the resonant frequency of the laser resonator and the resonant frequency of the microcavity structure in cooperation with the optical delay line.

5. The arc-frequency comb device of any one of claims 2-4, wherein, The optical delay line adopts any one of a spiral waveguide structure and a multi-stage ring waveguide structure.

6. The arc light frequency comb device of claim 1, wherein, The microcavity structure adopts any one of a micro-ring resonant cavity and an FP cavity.

7. The arc light frequency comb device of claim 1, wherein, The laser resonant cavity further comprises a filter. The filter is arranged in an optical path between the delay tuning unit and the beam splitter. The filter is configured to filter out non-target wavelength light other than the arc state light frequency comb. The filter adopts any one of a micro-ring filter and an MZI filter.

8. The arc light frequency comb device of claim 1, wherein, The laser resonant cavity further comprises an isolator. The isolator is arranged in an optical path between the delay tuning unit and the beam splitter. The isolator is configured to ensure one-way transmission of the arc state light frequency comb from the delay tuning unit to the beam splitter.

9. An arc-sub-femtosecond system, characterized in that, The arc light frequency comb system employs the arc light frequency comb device as claimed in any one of claims 1-8.

10. A communication device, characterized by The communication device employs the arc light frequency comb system as claimed in claim 9.

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