Broad-wavelength fiber array based on thin-film lithium niobate fiber

Abstract

The present invention relates to the field of optical fiber technology, and further to a wide-wavelength optical fiber array based on thin-film lithium niobate optical fiber. It comprises: a substrate, a dispersion compensator, an optical coupler and an optical fiber array; a lithium niobate thin film formed by lithium niobate deposition is disposed on the substrate; a waveguide structure is formed on the lithium niobate thin film by photolithography and etching; the optical fiber array comprises a plurality of optical fibers; the optical coupler is used to couple the optical signal in the waveguide structure to the optical fiber array or to couple the optical signal in the optical fiber array to the waveguide structure; the dispersion compensator is used to perform dispersion compensation on all optical fibers in the optical fiber array. The present invention solves many problems in the prior art, such as insufficient dispersion compensation, signal distortion and signal loss caused by nonlinear effects, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fibers, and in particular relates to a wide-wavelength optical fiber array based on thin-film lithium niobate optical fibers. Background Art

[0002] In modern optical communication systems, fiber-optic communication has become one of the main technologies for long-distance data transmission due to its advantages of high bandwidth, low loss and strong anti-interference ability. The core of the fiber-optic communication system lies in the efficient transmission and processing of optical signals. However, with the continuous increase in data transmission rate and transmission distance, traditional fiber-optic systems face many challenges in terms of dispersion, nonlinear effects and signal loss.

[0003] Existing fiber-optic communication systems mainly rely on standard single-mode fiber (SMF) for data transmission. However, during high-speed transmission and long-distance transmission, the dispersion effect in the optical fiber will cause the broadening and deformation of the optical pulse, thereby causing signal distortion. Dispersion can be divided into group velocity dispersion (GVD) and higher-order dispersion (HOD), both of which will have an adverse effect on the transmission quality of the signal. In order to overcome the dispersion effect, researchers have developed various dispersion compensation technologies, such as dispersion compensating fiber (DCF) and dispersion compensation module (DCM). These technologies offset the accumulated dispersion effect during transmission by introducing optical fibers or optical devices with opposite dispersion characteristics. However, the dispersion compensation technology itself has complexity and cost issues, and the dispersion compensation effect is still limited under high data rates and long-distance transmission. In addition, nonlinear effects in optical fibers, especially the Kerr effect, cause the phase of the optical signal to change with the light intensity, which in turn causes self-phase modulation (SPM) and cross-phase modulation (XPM). These nonlinear effects are particularly significant under high-power transmission, resulting in signal distortion and distortion. In the prior art, power limiters and nonlinear compensation techniques are used to mitigate the impact of nonlinear effects, but these methods often increase the complexity and cost of the system, and in practical applications, the effect of nonlinear compensation is still limited. The loss of optical signals is also a key issue, especially in long-distance transmission, where the signal strength will significantly decay as the transmission distance increases. In order to compensate for signal loss, the prior art generally uses optical fiber amplifiers such as erbium-doped fiber amplifiers (EDFA) to enhance the signal. However, the noise and gain flatness problems introduced by the amplifier also have a negative impact on system performance.

[0004] On the basis of existing technologies, some research on new materials and new structures has also made some progress. For example, lithium niobate (LiNbO) is widely used in optical modulators and optical switches due to its excellent optical properties and nonlinear effects. However, the application of lithium niobate to waveguide and optical fiber structures in optical fiber communication systems, especially efficient transmission over a wide wavelength range, remains a challenge. In addition, how to achieve efficient compensation for dispersion and nonlinear effects in actual optical fiber systems is also an urgent problem to be solved. Summary of the invention

[0005] The main purpose of the present invention is to provide a wide-wavelength optical fiber array based on thin-film lithium niobate optical fiber. By utilizing the excellent optical properties and nonlinear effects of lithium niobate thin films, as well as wide wavelength adaptability, the present invention provides an efficient, stable and flexible optical fiber communication solution, which promotes the development and application of optical communication technology. These technical improvements not only solve many problems in the prior art, such as insufficient dispersion compensation, signal distortion and signal loss caused by nonlinear effects, but also significantly improve the overall performance of the optical fiber communication system.

[0006] In order to solve the above problems, the technical solution of the present invention is implemented as follows: a wide-wavelength optical fiber array based on thin-film lithium niobate optical fiber, which includes: a substrate, a dispersion compensator, an optical coupler and an optical fiber array; a lithium niobate thin film formed by lithium niobate deposition is disposed on the substrate; a waveguide structure is formed on the lithium niobate thin film by photolithography and etching; the optical fiber array includes n optical fibers; the optical coupler is used to couple the optical signal in the waveguide structure to the optical fiber array or to couple the optical signal in the optical fiber array to the waveguide structure; the dispersion compensator is used to perform dispersion compensation on all optical fibers in the optical fiber array.

[0007] Furthermore, the optical coupler couples the optical signal in the waveguide structure to the optical fiber array or couples the optical signal in the optical fiber array to the waveguide structure by using end face coupling or bevel coupling.

[0008] Furthermore, the process of the dispersion compensator performing dispersion compensation on all optical fibers in the optical fiber array specifically includes: calculating the coupling efficiency when the optical coupler couples the optical signal in the waveguide structure to the optical fiber array; based on the coupling efficiency, defining the transmission equation of the optical signal in the optical fiber; solving the transmission equation to obtain the pulse envelope signal of the optical signal transmitted in the optical fiber; performing Fourier transform on the pulse envelope signal to obtain a frequency domain signal; designing a dispersion compensation filter, applying the dispersion compensation filter to the frequency domain signal, and compensating for the group velocity dispersion and high-order dispersion of the frequency domain signal; performing inverse Fourier transform on the compensated frequency domain signal, converting it back to the time domain, and obtaining a time domain signal; compensating for the nonlinear phase offset in the time domain signal to obtain an offset compensation signal; and processing the offset compensation signal using a dispersion balance method to optimize the dispersion compensation effect.

[0009] Furthermore, the coupling efficiency η when the optical coupler couples the optical signal in the waveguide structure to the optical fiber array is calculated using the following formula:

[0010]

[0011] Among them, E wg (x, y) is the electric field distribution in the waveguide structure; E fiber (x,y) is the electric field distribution in the optical fiber; is the complex conjugate of the fiber electric field; n eff,wg is the effective refractive index of the waveguide; n eff,fiber is the effective refractive index of the optical fiber; x and y are the X-axis and Y-axis coordinates in the transverse space respectively; β wg is the propagation constant of the waveguide structure; L wg is the length of the waveguide structure; α wg is the attenuation coefficient of the waveguide structure.

[0012] Furthermore, the electric field distribution in the waveguide structure is obtained by solving the following waveguide equation:

[0013]

[0014] in, is the free space wave number, λ is the wavelength, n wg (x, y) is the refractive index distribution in the waveguide structure, β wg It is the propagation constant of the waveguide structure, which represents the phase change rate of the optical signal when it propagates in the waveguide structure; is the Laplace operator;

[0015] The electric field distribution in the optical fiber is obtained by solving the following optical fiber mode field equation:

[0016]

[0017] Among them, n fiber (x, y) is the refractive index profile of the optical fiber, β fiber is the propagation constant of the optical fiber, representing the phase change rate of the optical signal when it propagates in the optical fiber; γ is the nonlinear coefficient describing the Kerr effect.

[0018] Furthermore, the dispersion compensator, based on the coupling efficiency, defines the transmission equation of the optical signal in the optical fiber using the following formula:

[0019]

[0020] Among them, A(z,t) is the pulse envelope, z is the propagation distance of the optical signal in the optical fiber, t is the propagation time of the optical signal in the optical fiber, α is the loss coefficient, β2 is the second-order dispersion coefficient, β3 is the third-order dispersion coefficient, γ is the nonlinear coefficient, which is the set value; Γ is the amplification gain in the optical fiber; i is the imaginary number sign; is the median wavelength of the wide-wavelength optical fiber; max is the upper wavelength limit of the wide-wavelength optical fiber; min It is the lower wavelength limit of wide wavelength optical fiber.

[0021] Furthermore, the transfer function H(ω) of the dispersion compensation filter is expressed using the following formula:

[0022]

[0023] Where L is the fiber length and ω is the angular frequency.

[0024] Furthermore, let A comp (z, t) is the time domain signal obtained by inverse Fourier transforming the compensated frequency domain signal back to the time domain; the nonlinear phase offset in the time domain signal is compensated using the following formula to obtain the offset compensation signal A nlc (z,t):

[0025]

[0026] Among them, A nlc (z, t) is the signal after nonlinear compensation; ∈ is the adjacent pulse interference coefficient; T is the pulse period; L eff is the effective length, which represents the length over which the optical signal effectively participates in the interaction in the nonlinear or attenuation process.

[0027] Furthermore, the dispersion compensation effect is optimized by processing the offset compensation signal using the dispersion balance method through the following formula:

[0028]

[0029] Among them, A balance (z, t) is the offset compensation signal after processing using the dispersion balance method; L balance It is the equilibrium length, which is the characteristic length for achieving a dynamic balance between dispersion effect and nonlinear effect.

[0030] Furthermore, the equilibrium length is calculated using the following formula:

[0031]

[0032] Where P0 is the peak power of the optical signal.

[0033] The wide-wavelength optical fiber array based on thin-film lithium niobate optical fiber of the present invention has the following beneficial effects: lithium niobate film as the core material significantly improves the overall performance of the optical fiber array due to its excellent optical properties and nonlinear effects. Lithium niobate material has broadband transparency and high electro-optical effect, so that it can show excellent transmission performance in a wide wavelength range. This feature enables the optical fiber array to work in a wider wavelength range, meeting the needs of modern optical communication systems for high bandwidth and multi-wavelength transmission. In addition, the high nonlinear effect of lithium niobate material enables it to perform well in modulation and switching applications, further improving the flexibility and performance of the system. In terms of optical signal coupling, the present invention utilizes the high refractive index and nonlinear effect of lithium niobate film, and combines the two modes of end-face coupling and bevel coupling to provide flexible options for the coupling of optical signals. Both coupling modes can achieve efficient signal coupling in different application scenarios, significantly improving the adaptability and flexibility of the system. The end-face coupling structure is simple and suitable for cost-sensitive applications, while the bevel coupling can work under higher coupling efficiency and anti-interference requirements. This diversified coupling mode reduces coupling loss and improves transmission quality. The innovation of the present invention in dispersion compensation is particularly prominent. The dispersion effect of the optical signal is compensated in detail by calculating the coupling efficiency, defining the transmission equation and Fourier transform. The lithium niobate film has a stable refractive index and excellent dispersion compensation capability in a wide wavelength range, which enables the dispersion compensator to effectively compensate for group velocity dispersion and high-order dispersion, ensuring high-quality transmission of signals in a wide wavelength range. This wide wavelength adaptability and efficient dispersion compensation enable the system to maintain excellent performance in high data rates and long-distance transmission, reduce signal distortion, and improve transmission stability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic structural diagram of a wide-wavelength optical fiber array based on thin-film lithium niobate optical fiber provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] The following are detailed descriptions of each.

[0037] Example 1: Reference Figure 1, a wide-wavelength optical fiber array based on thin-film lithium niobate optical fiber, comprising: a substrate, a dispersion compensator, an optical coupler and an optical fiber array; a lithium niobate thin film formed by lithium niobate deposition is disposed on the substrate; a waveguide structure is formed on the lithium niobate thin film by photolithography and etching; the optical fiber array comprises n optical fibers; the optical coupler is used to couple the optical signal in the waveguide structure to the optical fiber array or to couple the optical signal in the optical fiber array to the waveguide structure; the dispersion compensator is used to perform dispersion compensation on all optical fibers in the optical fiber array.

[0038] Specifically, lithium niobate (LiNbO) is a material with excellent optical transparency and significant electro-optical effect, and is widely used in the fields of optoelectronics and photonics. In this embodiment, lithium niobate is deposited on a substrate to form a thin film as a waveguide material. The electro-optical effect of the lithium niobate film means that its refractive index can be changed by applying an electric field, thereby achieving modulation and control of the optical signal. Based on this characteristic, the lithium niobate film has become an ideal material for manufacturing high-performance optical waveguides. The process of forming a waveguide structure on a lithium niobate film mainly includes photolithography and etching. First, a layer of photoresist is coated on the surface of the lithium niobate film, and the pre-designed waveguide pattern is transferred to the photoresist by photolithography. Then, the unexposed photoresist portion is removed by development, leaving the waveguide pattern. Then, chemical etching or ion beam etching technology is used to etch away the portion of the lithium niobate film that is not covered by the photoresist to form an actual waveguide structure. This fine manufacturing process ensures the high precision of the waveguide structure, thereby effectively controlling the propagation path of the optical signal and reducing loss and interference. The optical fiber array is another important component of the system. It consists of multiple optical fibers and is used to transmit and distribute optical signals. In this embodiment, each optical fiber in the optical fiber array can transmit optical signals of different wavelengths, reflecting the wide wavelength characteristics. In order to achieve efficient coupling of optical signals between the waveguide structure and the optical fiber array, an optical coupler is used. The optical coupler can be implemented by a variety of technologies, such as a gradient refractive index structure or a microlens array. Its main function is to couple the optical signal in the waveguide structure to the optical fiber array, or to couple the optical signal in the optical fiber array to the waveguide structure, to ensure efficient transmission and minimum loss of the optical signal. Dispersion compensators play a vital role in optical communication systems. Due to the dispersion effect of optical fibers, light of different wavelengths propagates at different speeds in optical fibers, resulting in signal distortion. In order to solve this problem, the present embodiment integrates a dispersion compensator to perform dispersion compensation on all optical fibers in the optical fiber array. Dispersion compensation technology can be in the form of fiber gratings or photonic crystals. Fiber gratings perform different degrees of delay compensation on optical signals of different wavelengths by designing a specific refractive index distribution, thereby reducing the distortion caused by dispersion. Photonic crystals use the bandgap effect of their periodic structure to precisely control the propagation characteristics of optical signals and achieve dispersion compensation. The combination of these technologies enables optical fiber arrays to maintain high-quality signal transmission over a wide wavelength range. The excellent optical and electro-optical properties of lithium niobate film as a waveguide material make the transmission and modulation of optical signals more efficient. Secondly, the fine waveguide structure formed by lithography and etching technology can precisely control the propagation path of optical signals and improve the stability and transmission efficiency of the system. In addition, the integrated dispersion compensator effectively solves the signal distortion problem caused by the dispersion effect, ensuring high-quality optical signal transmission over a wide wavelength range.

[0039] Embodiment 2: The optical coupler couples the optical signal in the waveguide structure to the optical fiber array or couples the optical signal in the optical fiber array to the waveguide structure by using end face coupling or bevel coupling.

[0040] Specifically, the core of Example 2 lies in the design of the optical coupler, which specifically adopts one of the two methods of end-face coupling or bevel coupling to couple the optical signal in the waveguide structure to the optical fiber array, or to couple the optical signal in the optical fiber array to the waveguide structure. This diversified coupling method is intended to improve the transmission efficiency and quality of the optical signal and meet the needs of different application scenarios. End-face coupling is a direct and efficient coupling method, which enables the optical signal to be effectively transmitted between the two by closely aligning the end face of the optical fiber with the end face of the waveguide structure. The advantages of this coupling method are simple structure and low implementation cost, but its alignment accuracy requirements are high, and a small alignment error may cause serious loss of the optical signal. Despite this, end-face coupling is still widely used in many applications, especially when a simple and economical coupling solution is required. Bevel coupling designs a specific bevel angle on the end face of the optical fiber and the waveguide structure, so that the optical signal can be transmitted from one medium to another by reflection or refraction. This design can optimize the transmission path of the optical signal, reduce loss and reflection, and thus provide higher coupling efficiency and better anti-interference performance. Bevel coupling shows better stability in the face of environmental changes, such as temperature changes or mechanical vibrations, and is suitable for application scenarios requiring high reliability. However, the manufacturing process of bevel coupling is relatively complex, requiring high-precision processing equipment and technology to ensure the accuracy of the bevel angle and the optimal coupling effect of the optical signal. By selecting one of end face coupling or bevel coupling, Example 2 provides a flexible coupling solution, and the most suitable coupling method can be selected according to specific application requirements. This diversified design not only improves the adaptability and flexibility of the system, but also significantly improves the overall performance of optical signal transmission. Compared with the prior art, this embodiment shows significant innovation in the selection and optimization of coupling methods. Through precise design and efficient coupling, the loss and distortion of optical signals during transmission are effectively reduced, ensuring high-quality transmission of signals. This innovative coupling design has important application prospects in the fields of optical communications and photonics, and can meet the needs of optical communication systems with higher data rates and greater bandwidth in the future.

[0041] Embodiment 3: The process of the dispersion compensator performing dispersion compensation on all optical fibers in the optical fiber array specifically includes: calculating the coupling efficiency when the optical coupler couples the optical signal in the waveguide structure to the optical fiber array; based on the coupling efficiency, defining the transmission equation of the optical signal in the optical fiber; solving the transmission equation to obtain the pulse envelope signal of the optical signal transmitted in the optical fiber; performing Fourier transform on the pulse envelope signal to obtain a frequency domain signal; designing a dispersion compensation filter, applying the dispersion compensation filter to the frequency domain signal, and compensating for the group velocity dispersion and high-order dispersion of the frequency domain signal; performing inverse Fourier transform on the compensated frequency domain signal, converting it back to the time domain, and obtaining a time domain signal; compensating for the nonlinear phase offset in the time domain signal to obtain an offset compensation signal; using the dispersion balance method to process the offset compensation signal to optimize the dispersion compensation effect.

[0042] Specifically, the calculation of coupling efficiency is based on the energy loss of the optical signal transmitted from the waveguide structure to the optical fiber array. The design of the optical coupler needs to consider the geometric matching and optical property matching between the waveguide and the optical fiber. When the optical signal in the waveguide structure is coupled to the optical fiber, it needs to be efficiently converted between the two through the optical coupler. This process involves phenomena such as refraction, reflection and transmission of light. In order to achieve high coupling efficiency, the optical coupler is usually designed as a gradient refractive index structure or a microlens array to minimize the reflection and scattering loss of the optical signal during the medium conversion process. In the design stage, it is necessary to accurately simulate and analyze the geometric parameters, refractive index distribution and incident angle of the waveguide and optical fiber, and use computer simulation tools such as finite difference time domain method (FDTD) or finite element method (FEM) to model and simulate the propagation path of the optical signal in detail. These simulation tools can help designers optimize the geometric structure and material selection of the coupler to achieve the best coupling efficiency. In addition to geometric and optical matching, surface roughness and manufacturing errors are also important factors affecting coupling efficiency. High-precision manufacturing processes and surface treatment technologies can effectively reduce these errors, thereby improving the actual coupling efficiency. In the actual measurement process, the coupling efficiency can be accurately measured using equipment such as spectrum analyzers and power meters. The coupling efficiency value can be obtained by measuring the intensity of the optical signal before and after coupling and comparing them.

[0043] The coupling efficiency determines the initial intensity of the optical signal entering the optical fiber, which is the basis for the definition of the transmission equation. The transmission of optical signals in optical fibers is affected by dispersion, attenuation and nonlinear effects, all of which are reflected in the transmission equation. The transmission equation is used to describe the evolution of optical signals in optical fibers, including their amplitude, phase and spectral characteristics. The dispersion effect causes optical signals of different frequency components to propagate at different speeds, causing signal broadening; the attenuation effect describes the energy loss of optical signals when they are transmitted in optical fibers, which is usually caused by the absorption and scattering of optical fiber materials; and nonlinear effects include self-phase modulation and cross-phase modulation, which affect the phase and intensity of optical signals. In order to accurately describe these phenomena, the transmission equation must contain mathematical expressions of these influencing factors. First, according to the initial conditions determined by the coupling efficiency, the intensity and phase distribution of the optical signal when it enters the optical fiber become the starting parameters of the equation. Then, by considering the dispersion effect, the dispersion parameters are introduced into the transmission equation. These parameters characterize the dispersion characteristics of the optical fiber material and the difference in propagation speed of different frequency components. Secondly, the attenuation effect is reflected in the transmission equation by introducing the attenuation coefficient, which describes the law of the attenuation of the optical signal with increasing distance. Nonlinear effects are represented by nonlinear coefficients, which are related to the nonlinear properties of the fiber material and are used to describe the effect of signal intensity on phase changes. The solution of the transmission equation usually involves numerical methods, such as the finite difference method or the split-step Fourier method, which can handle complex nonlinear and dispersion terms. Through numerical solution, the amplitude and phase distribution of the optical signal at different positions and time points in the optical fiber can be obtained, thereby predicting the changes of the signal during transmission. This information is crucial to understanding the performance of optical fiber communication systems, especially when designing and optimizing optical fiber links. Efficient transmission equations can accurately predict the performance of optical signals under various transmission conditions, helping engineers design optical fiber communication systems with optimal performance.

[0044] The transmission equation is usually the nonlinear Schrödinger equation (NLSE), which comprehensively considers the dispersion, attenuation and nonlinear effects in the optical fiber. By solving this equation, the time domain pulse envelope signal of the optical signal can be obtained, which describes the propagation process and changes of the optical pulse in the optical fiber. Numerical solution methods such as the split-step Fourier method (SSFM) are commonly used methods. By alternating calculations between the time domain and the frequency domain, nonlinear and linear effects are processed to accurately simulate the propagation of optical pulses. After obtaining the time domain pulse envelope signal, the next step is to perform Fourier transform on it to obtain the frequency domain representation of the optical signal. Fourier transform is a basic tool in signal processing. It converts the time domain signal to the frequency domain and reveals the spectral components of the signal. The frequency domain signal provides information about the frequency distribution of the optical pulse, which is the key to understanding and compensating for the dispersion effect. The dispersion effect refers to the fact that different frequency components in the optical signal propagate at different speeds, resulting in pulse broadening and deformation. In the frequency domain, dispersion is manifested as a change in phase with frequency, so the frequency domain representation can directly reflect the impact of dispersion on the optical signal. Dispersion compensation filters are designed to compensate for the group velocity dispersion and high-order dispersion of optical signals in the frequency domain. The design of the filter is based on the phase characteristics of the frequency domain signal. The purpose is to restore the pulse shape by introducing corresponding phase compensation so that each frequency component can arrive synchronously. The signal broadening caused by group velocity dispersion can be processed by a linear dispersion compensator, while high-order dispersion requires a more complex filter design. The filter usually uses technologies such as fiber Bragg gratings or photonic crystals to achieve phase compensation of frequency domain signals by precisely controlling the refractive index distribution or periodic structure. After applying the dispersion compensation filter to the frequency domain signal, the dispersion effect of the frequency domain signal can be effectively compensated. By adjusting the phase response of the filter, the phase relationship of each frequency component in the optical signal is restored to a state not affected by dispersion. When the processed frequency domain signal returns to the time domain, its group velocity and high-order dispersion effects are compensated, ensuring the integrity and shape of the optical signal. The effect of dispersion compensation is directly related to the performance of the communication system. Especially in long-distance and high-speed transmission, dispersion will significantly affect the signal quality and bit error rate, so effective dispersion compensation is crucial. The compensated frequency domain signal is converted back to the time domain through the inverse Fourier transform and restored to the time domain signal. The inverse Fourier transform recombines the phase and amplitude information in the frequency domain into a time domain signal. The time domain signal after dispersion compensation should be close to the original input signal. The signal processed in this way has good pulse shape and delay characteristics in the time domain, reducing the distortion caused by dispersion. The whole process is not only a mathematical transformation and compensation, but also a deep understanding and application of the propagation characteristics of optical signals. Converting the time domain signal to the frequency domain through Fourier transform, designing and applying the dispersion compensation filter, and then returning to the time domain through inverse Fourier transform, this series of steps ensures the high-quality transmission of optical signals in optical fibers.

[0045] Nonlinear phase shifts are mainly caused by nonlinear phenomena such as self-phase modulation (SPM) and cross-phase modulation (XPM) in optical fibers. These effects cause the phase of the signal to change with the light intensity, which causes pulse distortion and broadening. In order to compensate for these nonlinear phase shifts, an accurate compensation algorithm or device is required, such as a phase modulator, which introduces a phase compensation signal to offset the phase change caused by nonlinearity, thereby restoring the original phase characteristics of the signal. The process of compensating for nonlinear phase shifts first requires accurate measurement or estimation of the phase shift in the signal. By analyzing the time domain and frequency domain characteristics of the optical signal, the specific impact of the nonlinear effect on the phase is determined. Then, based on these measurement results, the corresponding compensation strategy is designed. Phase modulators are commonly used compensation devices that can dynamically adjust the phase of the output signal according to the light intensity of the input signal to offset the phase shift caused by the nonlinear effect. In this way, the compensated signal has a more stable phase relationship and reduces the distortion caused by the nonlinear effect. After obtaining the offset compensation signal after compensation, the next step is to process it using the dispersion balance method to optimize the dispersion compensation effect. The dispersion balancing method is an iterative optimization technique that gradually optimizes the transmission characteristics of the signal by introducing alternating dispersion compensation and nonlinear effect management in the optical signal transmission link. The core idea of ​​this method is to accurately control the interaction of dispersion and nonlinear effects in different sections of the optical fiber link to achieve the best signal transmission performance. In the dispersion balancing method, the optical fiber link is usually divided into several sections, and optical fibers or dispersion compensation modules with positive and negative dispersion are introduced into each section respectively, so that the overall dispersion effect is balanced and optimized in the whole link. In this way, the accumulation of dispersion and nonlinear effects can be controlled in each section of the optical fiber to avoid excessive accumulation of a single effect leading to signal quality degradation. In the specific implementation process, the dispersion balancing method needs to be combined with precise mathematical modeling and numerical simulation to optimize the parameters and configuration of the dispersion compensation module to ensure that the dispersion and nonlinear effects of each section of the optical fiber offset each other, so as to achieve the best signal transmission effect. In addition, the dispersion balancing method can also be combined with dynamic dispersion management technology to adapt to different transmission conditions and changes in signal characteristics by real-time monitoring and adjusting the dispersion compensation amount in the optical fiber link. This dynamic adjustment can be achieved through an automatic control system, using a feedback mechanism to continuously optimize the dispersion compensation effect. Through the combination of dispersion balance and dynamic management, optical fiber communication systems can maintain high-quality signal transmission over long distances, reduce bit error rates and signal distortion, and improve system reliability and stability. Compensating for nonlinear phase offsets in time domain signals and processing offset compensation signals using dispersion balance methods are crucial steps in optical fiber communications. This process involves not only precise phase compensation technology, but also requires the combination of dispersion management and optimization technology to ensure high quality and stability of optical signals over long distances. By compensating for nonlinear phase offsets, the phase relationship of the signal is restored, reducing distortion caused by nonlinear effects.Subsequently, the dispersion balancing method is used to optimize the signal transmission characteristics by alternating dispersion compensation and nonlinear management.

[0046] Embodiment 4: The coupling efficiency η when the optical coupler couples the optical signal in the waveguide structure to the optical fiber array is calculated using the following formula:

[0047]

[0048] Among them, E wg (x, y) is the electric field distribution in the waveguide structure; E fiber (x, y) is the electric field distribution in the optical fiber; is the complex conjugate of the fiber electric field; n eff,wg is the effective refractive index of the waveguide; n eff,fiber is the effective refractive index of the optical fiber; x and y are the X-axis and Y-axis coordinates in the transverse space respectively; β wg is the propagation constant of the waveguide structure; L wg is the length of the waveguide structure; α wg is the attenuation coefficient of the waveguide structure.

[0049] Specifically, in Example 4, the coupling efficiency calculation formula for coupling the optical signal in the waveguide structure to the optical fiber array by the optical coupler involves comprehensive consideration of multiple optical parameters and physical effects. The core of this formula is to describe the effectiveness of the transmission of the optical signal between the waveguide and the optical fiber. Through multiple factors such as the overlap integral of the electric field distribution, the correction of the attenuation effect, and the phase matching, the energy transfer and phase change in the coupling process are analyzed in detail. First, the electric field distribution in the waveguide structure and the electric field distribution in the optical fiber are the basis for the calculation of the coupling efficiency. The electric field distribution E wg (x,y) and E fiber (x,y) describes the spatial distribution of the optical signal on the cross-section of the waveguide and optical fiber. The overlap integral of the two electric field distributions can be used to evaluate the degree of spatial matching between the two. The overlap integral reflects the overlap of the electric field in space and represents the energy coupling efficiency between the waveguide and the optical fiber. This overlap integral takes into account the amplitude and phase of the electric field, and covers the entire cross-section through the integral area to ensure that the calculation results reflect the actual coupling situation. In the process of coupling the optical signal from the waveguide to the optical fiber, the attenuation effect of the optical signal is a factor that cannot be ignored. The attenuation effect is determined by the attenuation coefficient and length of the waveguide structure. The attenuation coefficient of the waveguide structure describes the energy loss caused by material absorption and scattering during the transmission of the optical signal, and the length represents the distance the optical signal is transmitted in the waveguide. Correction factor for attenuation effect Represents the energy loss of the optical signal after passing through a certain length of waveguide. This correction factor incorporates the attenuation effect into the calculation of coupling efficiency, ensuring that the calculation result more accurately reflects the actual energy transfer. Phase matching is another important factor. In the process of coupling the optical signal from the waveguide to the optical fiber, the change of the propagation phase is inevitable. The change of the propagation phase is determined by the propagation constant and length of the waveguide structure. The propagation constant describes the rate of phase change of the optical signal in the waveguide, while the waveguide length indicates the distance the optical signal is transmitted in the waveguide. Phase matching factor Describes the phase change of the optical signal after it has traveled a certain distance in the waveguide. This factor ensures that the overlap integral result accurately reflects the phase matching of the optical signal in the waveguide, thereby improving the calculation accuracy of the coupling efficiency. In addition to spatial matching, attenuation effect and phase matching, refractive index matching is also an important part of the coupling efficiency calculation. The effective refractive index of the waveguide and optical fiber respectively describes the relative propagation speed of the optical signal in the two media. The ratio of the effective refractive index The overlap integral results are adjusted to reflect the relative efficiency of light propagation in waveguides and fibers. This ratio ensures that the calculations take into account not only energy transfer and phase matching, but also the differences in the optical properties of the two media, providing a more comprehensive evaluation of coupling efficiency. The formula fully describes the process of optical couplers coupling light signals from waveguide structures into fiber arrays. The overlap integral of the electric field distribution reflects the spatial matching, the attenuation correction factor accounts for the energy loss of the light signal in the waveguide, the phase matching factor describes the change in the propagation phase, and the refractive index ratio adjusts the results to reflect the optical properties of the different media.

[0050] Example 5: The electric field distribution in the waveguide structure is obtained by solving the following waveguide equation:

[0051]

[0052] in, is the free space wave number, λ is the wavelength, n wg (x, y) is the refractive index distribution in the waveguide structure, β wg It is the propagation constant of the waveguide structure, which represents the phase change rate of the optical signal when it propagates in the waveguide structure; is the Laplace operator;

[0053] The electric field distribution in the optical fiber is obtained by solving the following optical fiber mode field equation:

[0054]

[0055] Among them, n fiber (x, y) is the refractive index profile of the optical fiber, β fiberis the propagation constant of the optical fiber, representing the phase change rate of the optical signal when it propagates in the optical fiber; γ is the nonlinear coefficient describing the Kerr effect.

[0056] Specifically, the waveguide equation and the fiber mode field equation are partial differential equations that describe the propagation of electromagnetic waves in a medium, taking into account the refractive index distribution of the medium and the propagation characteristics of the optical signal. The waveguide equation describes the propagation behavior of the optical signal in the waveguide structure, taking into account the refractive index distribution and propagation constant in the waveguide, and these parameters determine the spatial distribution of the electric field in the waveguide. When the optical signal propagates in the waveguide, due to the geometric structure and material properties of the waveguide, the refractive index at different positions may be different, which will cause the propagation path and phase of the optical signal to change. This change is described by the Laplace operator and the refractive index distribution term in the waveguide equation. By solving the waveguide equation, the electric field distribution of the optical signal in the waveguide can be obtained, which describes the mode of the optical signal in the waveguide. Similarly, the fiber mode field equation describes the propagation behavior of the optical signal in the optical fiber, taking into account the refractive index distribution and nonlinear effects in the optical fiber. The refractive index distribution in the optical fiber reflects the refractive index change of the optical fiber material, while the nonlinear effect is described by the Kerr effect, that is, the intensity of the optical signal affects the refractive index of the optical fiber, thereby changing the electric field distribution. The nonlinear term in the fiber mode field equation describes this effect, indicating that the larger the electric field strength, the more significant the corresponding nonlinear effect. This nonlinear effect is particularly important in high-power optical signal transmission because it affects the phase and propagation speed of the signal. By solving the fiber mode field equation, the electric field distribution of the optical signal in the fiber can be obtained. This distribution describes the mode of the optical signal in the fiber and how it is affected by nonlinear effects. These electric field distributions are crucial to understanding and optimizing the coupling efficiency of optical signals. Coupling efficiency refers to the proportion of the optical signal energy in the waveguide that is effectively transmitted to the optical fiber. The degree of matching of the electric field distribution determines the coupling efficiency. By accurately solving the waveguide equation and the fiber mode field equation, the obtained electric field distribution can be used to calculate the coupling efficiency of the optical signal from the waveguide to the optical fiber. The calculation of the coupling efficiency involves the overlap integral of the electric field distribution, which reflects the degree of matching of the two electric fields in space. Efficient coupling requires that the electric field distributions in the waveguide and the optical fiber are as similar as possible to maximize the energy transfer efficiency.

[0057] Embodiment 6: A dispersion compensator, based on coupling efficiency, defines a transmission equation of an optical signal in an optical fiber and expresses it using the following formula:

[0058]

[0059] Among them, S(z,t) is the pulse envelope, z is the propagation distance of the optical signal in the optical fiber, t is the propagation time of the optical signal in the optical fiber, α is the loss coefficient, β2 is the second-order dispersion coefficient, β3 is the third-order dispersion coefficient, γ is the nonlinear coefficient, which is the set value; Γ is the amplification gain in the optical fiber; i is the imaginary number symbol; is the median wavelength of the wide-wavelength optical fiber; max is the upper wavelength limit of the wide-wavelength optical fiber; min It is the lower wavelength limit of wide wavelength optical fiber.

[0060] Specifically, the transmission equation in Example 6 describes in detail the propagation behavior of the optical signal in the optical fiber, taking into account various factors such as dispersion, nonlinear effects, loss, and amplification gain. This equation provides a mathematical model for accurately simulating the transmission of optical signals by combining pulse envelope, coupling efficiency, and various physical parameters. First, the pulse envelope A(z, t) represents the time domain distribution of the optical signal in the optical fiber, which includes the changes of the optical signal in space and time. The coupling efficiency η is the conversion efficiency of the optical signal during the transmission process from the waveguide structure to the optical fiber, which directly affects the initial intensity and subsequent propagation characteristics of the optical signal. The introduction of the coupling efficiency ensures that the equation can accurately reflect the energy loss and phase change in the actual coupling process. The loss coefficient α describes the energy loss of the optical signal when it is transmitted in the optical fiber, which is usually determined by the absorption and scattering characteristics of the optical fiber material. The introduction of the loss coefficient enables the equation to simulate the process in which the optical signal gradually weakens with the propagation distance. The dispersion effect is particularly important in optical fiber transmission, which includes second-order dispersion and third-order dispersion. The second-order dispersion coefficient β2 reflects the pulse broadening caused by group velocity dispersion, while the third-order dispersion coefficient β3 describes the impact of higher-order dispersion effects on optical signals. Dispersion effects cause the spectral components of optical signals to propagate at different speeds, causing signal broadening and distortion. By introducing these dispersion coefficients, the equation can accurately simulate the impact of dispersion effects on pulse shape and propagation characteristics. Nonlinear effects are very significant in high-power optical fiber transmission, mainly caused by the Kerr effect. The nonlinear coefficient γ describes the impact of optical signal intensity on the refractive index, thereby affecting the phase and intensity of the optical signal. Nonlinear effects can cause self-phase modulation and cross-phase modulation, which further change the propagation characteristics of optical signals. The nonlinear term in the transmission equation reflects this effect. By introducing the product of the nonlinear coefficient and the pulse intensity, the impact of nonlinear phase modulation on signal propagation is simulated. The amplification gain Γ describes the amplification effect of the optical signal in the optical fiber, which is usually provided by the optical fiber amplifier. The amplification gain can compensate for the loss of the optical signal during transmission and improve the signal strength and quality. The introduction of this parameter enables the equation to simulate the effect of optical fiber amplifier on signal enhancement, thereby ensuring the stability of the signal during long-distance transmission. The imaginary symbol i in the transmission equation is used to represent phase change, which is a common method for dealing with optical signal propagation. Phase change is closely related to nonlinear effects and dispersion effects. Complex representation can easily handle these interactions, making the equation more concise and easier to solve. The transmission equation combines these physical parameters to form a complex partial differential equation that describes the propagation behavior of optical signals in optical fibers. Numerical solution of this equation can obtain the distribution of optical signals at different propagation distances and time points, thereby analyzing the impact of various effects on signal propagation.

[0061] Embodiment 7: The transfer function H(ω) of the dispersion compensation filter is expressed using the following formula:

[0062]

[0063] Where L is the length of the optical fiber and ω is the angular frequency.

[0064] Specifically, the transfer function H(ω) is a complex exponential function with angular frequency ω as the variable, where i is an imaginary unit representing the phase change. and Represent the contribution of second-order and third-order dispersion to the phase, respectively. Through these terms, the filter can compensate for the dispersion effects of different orders, thereby restoring the integrity of the signal. The second-order dispersion coefficient β2 describes the group velocity dispersion (GVD), that is, light of different frequency components propagates at different speeds in the fiber, resulting in pulse broadening. The term is to compensate for this second-order dispersion effect. As the fiber length L increases, the impact of second-order dispersion on the signal becomes more significant, so the transfer function needs to introduce a phase difference with ω 2 The third-order dispersion coefficient β3 describes the frequency dependence of group velocity dispersion, that is, different frequency components not only propagate at different speeds, but also the speed difference varies with frequency. The third-order dispersion effect will lead to more complex pulse deformation, especially in broadband optical signals. The term is used to compensate for this third-order dispersion effect by introducing a phase 3The frequency-dependent distortion of the signal is corrected by a compensation term proportional to the phase compensation term. By combining these two compensations, the transfer function of the dispersion compensation filter can simultaneously handle the second-order and third-order dispersion effects, so that the compensated optical signal can restore its original form. The exponential form of the transfer function exp(i·phase compensation term) represents the cumulative effect of phase compensation, which is to adjust the phase of each frequency component of the signal so that they can arrive synchronously after passing through the optical fiber, thereby avoiding pulse broadening and deformation. L in the transfer function represents the length of the optical fiber, reflecting the accumulated dispersion effect of the optical signal during transmission. Therefore, the longer the optical fiber, the more significant the dispersion effect, and the compensation term in the transfer function needs to be increased accordingly. The angular frequency ω describes the frequency component of the signal, and the transfer function ensures that each frequency component is correctly compensated during the propagation process by adjusting the phase of different frequency components. In general, the transfer function H(ω) of the dispersion compensation filter corrects the dispersion effect of the optical signal during propagation in the optical fiber by introducing second-order and third-order dispersion compensation terms. This transfer function allows optical signals of different frequency components to remain synchronized after passing through the optical fiber through precise phase compensation, thereby avoiding signal broadening and distortion. In this way, dispersion compensation filters can significantly improve the signal transmission quality of optical fiber communication systems and ensure signal integrity and stability under long distance and high bandwidth conditions. This compensation mechanism is crucial to the efficient operation of modern optical fiber communication systems, and can effectively solve the signal distortion problem caused by dispersion and improve system performance and reliability.

[0065] Example 8: Assume A comp (z, t) is the time domain signal obtained by inverse Fourier transforming the compensated frequency domain signal back to the time domain; the nonlinear phase offset in the time domain signal is compensated using the following formula to obtain the offset compensation signal A nlc (z,t):

[0066]

[0067] Among them, A nlc (z, t) is the signal after nonlinear compensation; ∈ is the adjacent pulse interference coefficient; T is the pulse period; L eff is the effective length, which represents the length over which the optical signal effectively participates in the interaction in the nonlinear or attenuation process.

[0068] Specifically, the formula in Example 8 is used to compensate for the nonlinear phase offset in the time domain signal. The purpose is to make the signal more stable and accurate in the time domain by correcting the phase distortion caused by the nonlinear effect during the optical fiber transmission process. Nonlinear effects, especially the Kerr effect, will cause the phase of the optical signal to change with the change of light intensity, thereby causing signal distortion and distortion. In order to ensure the integrity and transmission quality of the signal, it is necessary to compensate for this nonlinear phase offset. In the formula, the compensation process is implemented by an exponential function, which contains the intensity information of the signal and the influence of adjacent pulses on the current pulse. In the formula for compensating for the nonlinear phase offset, the first thing to consider is the compensated time domain signal, which is obtained by inverse Fourier transforming the frequency domain signal and represents the distribution of the optical signal in the time domain. Since the optical signal will be affected by the nonlinear effect when it is transmitted in the optical fiber, the compensation of the nonlinear phase offset must reflect the actual situation of this influence. The nonlinear coefficient γ in the formula describes the intensity of the Kerr effect, which causes the phase of the optical signal to change with the change of intensity. The first part of the compensation term |A comp (z,t)| 2 Represents the influence of the intensity of the signal at the current moment on the phase, which reflects the effect of self-phase modulation. Self-phase modulation is a manifestation of the Kerr effect, that is, the phase of the optical signal will change due to its own intensity change. This intensity information appears in the formula in the form of a square, reflecting the square relationship between the signal strength and the phase change. The second part of the formula takes into account the interference effect of adjacent pulses, which is represented by the adjacent pulse interference coefficient ∈ and the pulse period T. The adjacent pulse interference coefficient reflects the degree of influence of adjacent pulses on the current pulse phase, while the pulse period describes the time interval of the signal. By summing the intensities of all adjacent pulses, the formula can accurately describe the phase modulation influence of adjacent pulses on the current pulse. This effect is called cross-phase modulation. This nonlinear effect is particularly obvious in high-power optical signal transmission, and effective compensation must be performed to ensure signal quality. The effective length L introduced in the formula eff is another key parameter, which indicates the length of the optical signal that effectively participates in the interaction during nonlinear or attenuation processes. The effective length is calculated by considering the attenuation characteristics of the optical fiber, reflecting the influence of the signal strength attenuation with distance during the actual transmission process. By introducing the effective length into the formula, the phase distortion caused by the nonlinear effect can be compensated more accurately to ensure the compensation effect. Through the compensation term in the form of an exponential function, the formula can dynamically adjust the nonlinear phase offset and correct the nonlinear influence on the optical signal during the transmission process. The compensated signal A nlc (z, t) is more stable in phase, reducing distortion caused by nonlinear effects. The processed signal maintains higher integrity and accuracy during long-distance transmission, improving the performance and reliability of the transmission system.

[0069] Embodiment 9: The dispersion compensation effect is optimized by processing the offset compensation signal using the dispersion balance method through the following formula:

[0070]

[0071] Among them, A balance (z, t) is the offset compensation signal after processing using the dispersion balance method; L balance It is the equilibrium length, which is the characteristic length for achieving a dynamic balance between dispersion effect and nonlinear effect.

[0072] Specifically, the formula in Example 9 processes the offset compensation signal through the dispersion balance method to optimize the dispersion compensation effect and ensure that the propagation of the optical signal in the optical fiber is more stable and accurate. The core idea of ​​this formula is to further optimize the optical signal by adjusting the balance between the dispersion effect and the nonlinear effect, so that it can maintain high quality and low distortion in long-distance transmission. The offset compensation signal A in the formula nlc (z, t) is the signal after nonlinear phase offset compensation, which has corrected the phase distortion caused by nonlinear effects. However, during fiber transmission, the dispersion effect will still affect the signal. Dispersion effects include second-order dispersion and third-order dispersion, which will cause the spectral components of the signal to propagate at different speeds, thereby causing pulse broadening and deformation. In order to further optimize signal transmission, the formula introduces a dispersion balance method, which achieves a dynamic balance between dispersion effect and nonlinear effect by adjusting the impact of second-order and third-order dispersion on the signal. The realization of dispersion balance depends on the balance length L balance , which is a key parameter, indicating that the dispersion effect and nonlinear effect cancel each other out at this length, so that the signal remains stable during transmission. The second-order dispersion term in the formula It is used to compensate for the group velocity dispersion (GVD) of the signal, that is, the optical signals with different frequency components propagate at different speeds, resulting in pulse broadening. By introducing a compensation term proportional to the second-order derivative in phase, the pulse broadening caused by the second-order dispersion can be effectively corrected, so that the propagation speeds of the various frequency components of the signal tend to be consistent. It is used to compensate for the third-order dispersion effect of the signal. This effect will lead to more complex frequency-dependent distortion. By introducing a compensation term proportional to the third-order derivative, the signal distortion caused by the third-order dispersion can be effectively corrected, so that the signal maintains better integrity in the spectrum. Combining the dispersion compensation of these two parts, through the adjustment of the exponential function, the dispersion compensation effect is reduced within the transmission length L. balanceThis process accurately adjusts the compensation amount of second-order and third-order dispersion so that the signal can offset the negative impact of the dispersion effect and maintain a dynamic balance of the nonlinear effect during transmission, thereby achieving optimized signal transmission. The implementation of the dispersion balancing method ensures the stability and low distortion of optical signals in long-distance transmission. By adjusting the balance between the dispersion effect and the nonlinear effect, the signal broadening and distortion caused by dispersion can be minimized while retaining the positive impact of the nonlinear effect on the signal. This method is particularly important in high-power optical signal transmission, because high-power signals are more susceptible to nonlinear and dispersion effects in long-distance transmission. Finally, the signal A after dispersion balancing is balance (z, t) has higher quality and lower distortion, providing more stable and efficient signal transmission for optical fiber communication systems. This optimization process not only improves the transmission performance of the system, but also provides technical support for achieving higher speed and longer distance optical communication. Through this precise compensation and balancing method, the reliability and transmission efficiency of optical fiber communication systems can be significantly improved, meeting the needs of modern communications for high bandwidth and high quality transmission.

[0073] Example 10: The equilibrium length is calculated using the following formula:

[0074]

[0075] Where P0 is the peak power of the optical signal.

[0076] Specifically, the formula in Example 10 describes the equilibrium length L balanceThe calculation method of the balanced length is used to achieve a dynamic balance between the dispersion effect and the nonlinear effect, thereby optimizing the transmission quality of the optical signal in the optical fiber. The calculation of the balanced length involves multiple key parameters, including the second-order dispersion coefficient β2, the third-order dispersion coefficient β3, the nonlinear coefficient γ and the peak power P0 of the optical signal. First, the second-order dispersion coefficient β2 in the formula describes the group velocity dispersion (GVD) when the optical signal propagates in the optical fiber. The group velocity dispersion causes the optical signals of different frequency components to propagate at different speeds, resulting in pulse broadening. The second-order dispersion effect is the main object of dispersion compensation because it has the most significant impact on the signal. The third-order dispersion coefficient β3 describes the variation of the dispersion effect with frequency, that is, the frequency-dependent dispersion effect. Although this high-order dispersion effect is relatively weak, it cannot be ignored in long-distance transmission. The β3 term in the formula is used to correct and compensate for the effects of the third-order dispersion. The nonlinear coefficient γ reflects the nonlinear effects in the optical fiber, mainly the Kerr effect. The Kerr effect causes the phase of the optical signal to change with the light intensity, thereby causing phase modulation and pulse distortion. The nonlinear effect is particularly obvious in high-power optical signal transmission, and accurate compensation is required to ensure signal quality. The peak power P0 of the optical signal directly affects the intensity of the nonlinear effect. The higher the power, the more significant the nonlinear effect. Balance length L balance The calculation formula combines these parameters to achieve a dynamic balance by adjusting the interaction between the second-order and third-order dispersion effects and the nonlinear effects. Specifically, the first part of the formula describes the combined effect of dispersion effects. Here, is the basic second-order dispersion compensation term, and It is a correction for the third-order dispersion effect, making the dispersion compensation more comprehensive and accurate. The second part of the formula It is the compensation for nonlinear effects. The nonlinear effect is proportional to the peak power of the optical signal. By introducing this term, the compensation amount can be accurately adjusted so that the nonlinear phase shift can be effectively corrected. The two parts are combined together to achieve a comprehensive balance between dispersion and nonlinear effects by taking the square root, so that the propagation of the optical signal in the optical fiber reaches the optimal state. The balanced length L calculated by this method is balance It means that at this length, the dispersion effect and nonlinear effect cancel each other out, making the signal propagation more stable and accurate. This is especially important for long-distance fiber transmission, because in long-distance transmission, the dispersion and nonlinear effects will accumulate, causing serious signal distortion. By accurately calculating the balance length, dynamic balance can be achieved in actual fiber-optic communication systems, significantly improving transmission quality and system performance.

[0077] In summary, the fiber array structure based on lithium niobate film includes the design of substrate, dispersion compensator, optical coupler and fiber array. By utilizing the excellent optical properties and nonlinear effects of lithium niobate film, a specific waveguide structure is formed on the substrate, which not only improves the transmission efficiency of optical signals, but also expands the working wavelength range. The lithium niobate film material has broadband transparency and high electro-optical effect, which enables it to exhibit excellent transmission performance in a wide wavelength range. Through the combination of dispersion compensator and optical coupler, the optical signal can be efficiently coupled between the waveguide and the optical fiber, and the dispersion can be effectively compensated, thereby ensuring the integrity and stability of the signal. The application of the two coupling modes of end coupling and bevel coupling performs well in utilizing the high refractive index and nonlinear effects of lithium niobate film. End coupling and bevel coupling provide flexible options for the coupling of optical signals, and can optimize the coupling efficiency and signal quality in a wide wavelength range. The high nonlinear effect and wide wavelength characteristics of lithium niobate material enable it to efficiently transmit optical signals in different coupling modes, thereby improving the adaptability and flexibility of the system. The working principle of the dispersion compensator is elaborated in detail through the steps of calculating coupling efficiency, defining transmission equations and Fourier transform. Lithium niobate film has a stable refractive index and excellent dispersion compensation ability in a wide wavelength range, so that the dispersion compensator can effectively compensate for group velocity dispersion and high-order dispersion, ensuring high-quality transmission of signals in a wide wavelength range. This wide wavelength adaptability, supported by lithium niobate materials, greatly improves the accuracy and stability of signal transmission. When calculating the coupling efficiency of the optical coupler, the high refractive index and nonlinear effect of lithium niobate film and the transmission characteristics of optical signals in a wide wavelength range are considered. The high refractive index and wide wavelength transparency of lithium niobate materials ensure the efficient transmission of optical signals between waveguides and optical fibers, and optimize system performance. The present invention significantly improves the conversion efficiency of optical signals between waveguides and optical fibers by optimizing the design of the optical coupler and utilizing the high refractive index and nonlinear effect of lithium niobate film. High coupling efficiency means less energy loss and higher signal strength, thereby improving transmission distance and quality. In the calculation of the electric field distribution of the waveguide and optical fiber, the refractive index distribution and nonlinear effect of the lithium niobate material are fully considered, so that the waveguide and optical fiber structure can achieve stable optical signal transmission in a wide wavelength range. In order to further improve the stability of signal transmission, the present invention also designs a dispersion compensation filter to correct the signal distortion caused by the dispersion effect through phase compensation. The dispersion characteristics of the lithium niobate film play a key role in this, ensuring the effective operation of the filter in a wide wavelength range, thereby maintaining the integrity and stability of the optical signal. This efficient dispersion compensation is particularly important for long-distance and high-bandwidth transmission, and can significantly improve the transmission performance of the system. In terms of nonlinear phase compensation, by correcting the phase distortion caused by the high nonlinear effect of the lithium niobate material, the stability and high-quality transmission of the signal in the time domain are ensured.By dynamically adjusting the phase compensation, the distortion caused by the nonlinear effect is reduced and the transmission quality of the signal is improved. In addition, the dispersion balance method is used to process the offset compensation signal, and the dynamic balance between the dispersion effect and the nonlinear effect is achieved through the wide wavelength and nonlinear characteristics of the lithium niobate film. This balancing method ensures the stability of the signal during transmission, reduces the negative impact of the dispersion and nonlinear effects, and improves the integrity and quality of the signal. Finally, the present invention provides a formula for calculating the balance length, which comprehensively considers the second-order dispersion, third-order dispersion and nonlinear effects of the lithium niobate film, as well as the wide wavelength characteristics. By accurately calculating the balance length, the dynamic balance of the dispersion and nonlinear effects can be achieved in the actual optical fiber system, further optimizing the signal transmission quality. This technology ensures the efficient operation of the optical fiber communication system under long distance and high bandwidth conditions.

[0078] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wide wavelength optical fiber array based on thin film lithium niobate optical fiber, characterized in that: It includes: substrates, dispersion compensators, optical couplers, and fiber arrays; A lithium niobate film formed by lithium niobate deposition is disposed on the substrate; A waveguide structure is formed on the lithium niobate film by photolithography and etching; the optical fiber array includes n optical fibers; the optical coupler is used to couple the optical signal in the waveguide structure to the optical fiber array or to couple the optical signal in the optical fiber array to the waveguide structure; the dispersion compensator is used to perform dispersion compensation on all optical fibers in the optical fiber array; the process of the dispersion compensator performing dispersion compensation on all optical fibers in the optical fiber array specifically includes: calculating the coupling efficiency when the optical coupler couples the optical signal in the waveguide structure to the optical fiber array; based on the coupling efficiency, defining the transmission equation of the optical signal in the optical fiber; solving the transmission equation to obtain the pulse envelope signal of the optical signal transmitted in the optical fiber; Fourier transforming the pulse envelope signal to obtain a frequency domain signal; designing a dispersion compensation filter, applying the dispersion compensation filter to the frequency domain signal, compensating for the group velocity dispersion and high-order dispersion of the frequency domain signal; inverse Fourier transforming the compensated frequency domain signal, converting it back to the time domain, and obtaining a time domain signal; compensating for the nonlinear phase offset in the time domain signal to obtain an offset compensation signal; using a dispersion balance method to process the offset compensation signal to optimize the dispersion compensation effect.

2. The wide wavelength optical fiber array based on thin film lithium niobate optical fiber according to claim 1, characterized in that: The optical coupler couples the optical signal in the waveguide structure to the optical fiber array or couples the optical signal in the optical fiber array to the waveguide structure by using end face coupling or bevel coupling.

3. The wide wavelength optical fiber array based on thin film lithium niobate optical fiber according to claim 2, characterized in that: Use the following formula to calculate the coupling efficiency η when the optical coupler couples the optical signal in the waveguide structure into the optical fiber array: Among them, E wg (x, y) is the electric field distribution in the waveguide structure; E fiber (x, y) is the electric field distribution in the optical fiber; is the complex conjugate of the fiber electric field; n eff,wg is the effective refractive index of the waveguide; n eff,fiber is the effective refractive index of the optical fiber; x and y are the X-axis and Y-axis coordinates in the transverse space respectively; β wg is the propagation constant of the waveguide structure; L wg is the length of the waveguide structure; α wg is the attenuation coefficient of the waveguide structure.

4. The wide wavelength optical fiber array based on thin film lithium niobate optical fiber according to claim 3, characterized in that: The electric field distribution in the waveguide structure is obtained by solving the following waveguide equation: in, is the free space wave number, λ is the wavelength, n wg (x, y) is the refractive index distribution in the waveguide structure, β wg It is the propagation constant of the waveguide structure, which represents the phase change rate of the optical signal when it propagates in the waveguide structure; is the Laplace operator; The electric field distribution in the optical fiber is obtained by solving the following optical fiber mode field equation: Among them, n fiber (x, y) is the refractive index profile of the optical fiber, β fiber is the propagation constant of the optical fiber, representing the phase change rate of the optical signal when it propagates in the optical fiber; γ is the nonlinear coefficient describing the Kerr effect.

5. The wide wavelength optical fiber array based on thin film lithium niobate optical fiber according to claim 4, characterized in that: The dispersion compensator, based on the coupling efficiency, defines the transmission equation of the optical signal in the optical fiber using the following formula: Among them, A(z,t) is the pulse envelope, z is the propagation distance of the optical signal in the optical fiber, t is the propagation time of the optical signal in the optical fiber, α is the loss coefficient, β2 is the second-order dispersion coefficient, β3 is the third-order dispersion coefficient, γ is the nonlinear coefficient, which is the set value; Γ is the amplification gain in the optical fiber; i is the imaginary number sign; is the median wavelength of the wide-wavelength optical fiber; max is the upper wavelength limit of the wide-wavelength optical fiber; min It is the lower wavelength limit of wide wavelength optical fiber.

6. The wide wavelength optical fiber array based on thin-film lithium niobate optical fiber according to claim 5, characterized in that: The transfer function H(ω) of the dispersion compensation filter is expressed as follows: Where L is the fiber length and ω is the angular frequency.

7. The wide wavelength optical fiber array based on thin film lithium niobate optical fiber according to claim 6, characterized in that: Assume A comp (z, t) is the time domain signal obtained by inverse Fourier transforming the compensated frequency domain signal back to the time domain; the nonlinear phase offset in the time domain signal is compensated using the following formula to obtain the offset compensation signal A nlc (z,t): Among them, A nlc (z, t) is the signal after nonlinear compensation; ∈ is the adjacent pulse interference coefficient; T is the pulse period; L eff is the effective length, which represents the length over which the optical signal effectively participates in the interaction in the nonlinear or attenuation process.

8. The wide wavelength optical fiber array based on thin film lithium niobate optical fiber according to claim 7, characterized in that: The dispersion compensation effect is optimized by processing the offset compensation signal using the dispersion balance method through the following formula: Among them, A balance (z, t) is the offset compensation signal after processing using the dispersion balance method; L balance It is the equilibrium length, which is the characteristic length for achieving a dynamic balance between dispersion effect and nonlinear effect.

9. The wide wavelength optical fiber array based on thin-film lithium niobate optical fiber according to claim 8, characterized in that: The equilibrium length is calculated using the following formula: Where P0 is the peak power of the optical signal.

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