Method and system for self-similar evolution of femtosecond pulses in a chip-scale waveguide

Abstract

The present application relates to the technical field of stimulated emission devices, and particularly provides a method and system for self-similar evolution of femtosecond pulses in a chip-level waveguide, the method comprising: introducing input femtosecond pulses into an entrance section of a chip waveguide composed of birefringence heterogeneous materials; obtaining an initial pulse with internal space-time correlation; inputting the initial pulse into a distributed parameter dynamic compensation array in a middle section of the chip waveguide to form synchronous dynamic compensation for nonlinearity and dispersion, and obtaining an intermediate pulse with stable spectral width and phase distribution; inputting the intermediate pulse into an output coupler at an end of the waveguide; simultaneously solidifying a pulse time-domain envelope shape determined by dispersion truncation effect; and outputting femtosecond pulses with self-similar characteristics, stable shape and spectrum after processing by the coupler. The system comprises a space-time correlation processing module, a dynamic compensation synchronization module and a coupling processing module. The present application significantly improves controllability and output quality of femtosecond pulse evolution in an integrated waveguide.

Description

Technical Field

[0001] This invention relates to the field of stimulated emission device technology, and in particular to a method and system for the self-similar evolution of femtosecond pulses in a chip-scale waveguide. Background Technology

[0002] With the rapid development of integrated photonics and ultrafast optics, chip-scale waveguide systems have become the core platform for realizing high-density, low-power optical information processing. Femtosecond pulses, due to their extremely short pulse width and extremely high peak power, have shown great potential in fields such as precision spectral analysis, ultrafast optical communication, quantum information processing, and biomedical imaging. However, when femtosecond pulses propagate in submicron-scale chip waveguides, they are significantly affected by both nonlinear effects (such as self-phase modulation and four-wave mixing) and dispersion effects, leading to complex distortions in pulse shape, spectrum, and phase. Traditional pulse modulation methods often struggle to maintain stable pulse transmission in finite-sized integrated waveguides, severely limiting the efficient application of femtosecond pulses in chip-scale devices. Currently, how to achieve controllable, low-loss evolution of femtosecond pulses within confined waveguide structures has become one of the key scientific problems urgently needing breakthroughs in the field of integrated photonics. Self-similar evolution, as a special nonlinear dynamic process, enables pulses to maintain shape invariance during transmission while effectively managing the balance between nonlinearity and dispersion, providing an ideal theoretical framework for chip-scale femtosecond pulse processing. However, existing technologies have not yet fully solved how to achieve efficient and controllable self-similar evolution in the compact space of chip waveguides. Summary of the Invention

[0003] To achieve the above objectives, the present invention adopts the following technical solution: One aspect of the present invention provides a method for the self-similar evolution of femtosecond pulses in a chip-scale waveguide, comprising the following steps: The input femtosecond pulse is introduced into a chip waveguide inlet segment composed of a birefringent heteromaterial; the upper cladding of the inlet waveguide is composed of first-doped silicon dioxide treated by ion beam tilting implantation, and the lower cladding is composed of undoped second silicon dioxide, forming an asymmetric refractive index profile; the chip waveguide inlet segment synchronously preprocesses the spatiotemporal characteristics of the pulse; the asymmetric refractive index profile induces a non-uniform distribution of the femtosecond pulse electric field intensity within the waveguide cross-section, with its peak intensity region confined to the lower edge of the waveguide core near the lower cladding; the birefringence effect at the birefringent heteromaterial interface causes the group velocities of different polarization components in the pulse to separate, resulting in a predetermined spatiotemporal overlap of the optical fields at the leading and trailing edges of the femtosecond pulse in the early stages of transmission; thus, an initialization pulse with internal spatiotemporal correlation is obtained. The distributed parameter dynamic compensation array in the middle section of the waveguide of the initial pulse input chip is initialized. The distributed parameter dynamic compensation array is composed of a series of micro-units periodically arranged in the waveguide core layer. Each micro-unit is composed of a subwavelength grating structure formed by laser direct writing and an outer layer of electrically controlled phase change material. The period of the subwavelength grating structure is determined by the non-uniform intensity distribution information of the femtosecond pulse in the front section, making its scattering effect on the light field in the pulse peak region stronger than that in the edge region. The crystal state of the electrically controlled phase change material thin layer is controlled by the externally applied gradient electric field sequence and dynamically adjusted according to the pulse spectrum broadening degree monitored in real time. When the pulse spectrum broadening exceeds the threshold, the gradient electric field drives the electrically controlled phase change material to undergo a partial transition from an amorphous state to a crystalline state, changing the local effective refractive index of the grating structure, thereby specifically enhancing the scattering loss in the pulse peak region, forming synchronous dynamic compensation for nonlinearity and dispersion, and obtaining an intermediate pulse with a stable spectral width and phase distribution. The intermediate pulse is input to the output coupler at the end of the waveguide. The main body of the coupler is a gradually expanding tapered waveguide. The sidewalls of its tapered region are made of silicon-germanium alloy that has undergone high-temperature oxidation annealing, forming an oxide interface layer that thickens exponentially with the transmission distance. The increase in the thickness of the oxide interface layer causes the equivalent waveguide dispersion in the tapered region to be sharply enhanced in the transmission direction, forming a dispersion cutoff effect that forcibly terminates the trend of further pulse evolution. The end of the tapered waveguide is connected to the output straight waveguide. The core material of the straight waveguide is the same as that of the starting end of the tapered waveguide, but the upper and lower claddings of the straight waveguide are replaced with low-loss UV-curable polymers. The low-loss UV-curable polymers form a shape lock for the pulse shape at the dispersion cutoff point of the tapered waveguide and the interface of the straight waveguide. The locking mechanism originates from the absorption edge effect of the polymer cladding in the pulse frequency band. At the same time, the pulse time-domain envelope shape determined by the dispersion cutoff effect is cured. After processing by the coupler, the final output is a femtosecond pulse that maintains self-similar characteristics and has a stable shape and spectrum.

[0004] In another aspect, the present invention provides a self-similar evolution system for femtosecond pulses in a chip-scale waveguide, comprising: a spatiotemporal correlation processing module configured to guide an input femtosecond pulse into a chip waveguide inlet segment composed of a birefringent heteromaterial; the upper cladding of the inlet waveguide is composed of first-doped silicon dioxide treated by ion beam tilting implantation, and the lower cladding is composed of undoped second silicon dioxide, forming an asymmetric refractive index profile; the chip waveguide inlet segment synchronously preprocesses the spatiotemporal characteristics of the pulse; the asymmetric refractive index profile induces a non-uniform distribution of the electric field intensity of the femtosecond pulse within the waveguide cross-section, and its peak intensity region is constrained to the lower edge of the waveguide core near the lower cladding; the birefringence effect at the interface of the birefringent heteromaterial causes the group velocity of different polarization components in the pulse to separate, resulting in a preset spatiotemporal overlap of the optical fields at the leading and trailing edges of the femtosecond pulse in the early stage of transmission; thus obtaining an initial pulse with internal spatiotemporal correlation. The dynamic compensation synchronization module is configured to initialize the distributed parameter dynamic compensation array in the middle section of the waveguide of the pulse input chip. The distributed parameter dynamic compensation array consists of a series of micro-units periodically arranged in the waveguide core layer. Each micro-unit is composed of a subwavelength grating structure formed by laser direct writing and an outer layer of electrically controlled phase change material. The period of the subwavelength grating structure is determined by the non-uniform intensity distribution information of the femtosecond pulse in the front section, making its scattering effect on the light field in the pulse peak region stronger than that in the edge region. The crystal state of the electrically controlled phase change material thin layer is controlled by the externally applied gradient electric field sequence and dynamically adjusted according to the pulse spectrum broadening degree monitored in real time. When the pulse spectrum broadening exceeds the threshold, the gradient electric field drives the electrically controlled phase change material to undergo a partial transition from an amorphous state to a crystalline state, changing the local effective refractive index of the grating structure, thereby specifically enhancing the scattering loss in the pulse peak region, forming synchronous dynamic compensation for nonlinearity and dispersion, and obtaining an intermediate pulse with a stable spectral width and phase distribution. The coupling processing module is configured to input the intermediate pulse into the output coupler at the end of the waveguide. The main body of the coupler is a gradually expanding tapered waveguide, the sidewalls of which are made of silicon-germanium alloy that has undergone high-temperature oxidation annealing, forming an oxide interface layer that thickens exponentially with the transmission distance. The increase in the thickness of the oxide interface layer causes the equivalent waveguide dispersion in the tapered region to be sharply enhanced in the transmission direction, forming a dispersion cutoff effect, which forcibly terminates the trend of further pulse evolution. The end of the tapered waveguide is connected to the output straight waveguide. The core material of the straight waveguide is the same as that of the starting end of the tapered waveguide, but the upper and lower claddings of the straight waveguide are replaced with low-loss UV-curable polymers. The low-loss UV-curable polymers form a shape lock for the pulse shape at the dispersion cutoff point of the tapered waveguide and the interface of the straight waveguide. The locking mechanism originates from the absorption edge effect of the polymer cladding in the pulse frequency band. At the same time, the pulse time-domain envelope shape determined by the dispersion cutoff effect is cured. After processing by the coupler, the final output is a femtosecond pulse that maintains self-similar characteristics and has a stable shape and spectrum.

[0005] This invention achieves efficient self-similar evolution control of femtosecond pulses in chip-scale waveguides through multi-step synergistic action. By combining asymmetric waveguide structures with birefringence effects, it simultaneously modulates the spatial intensity distribution and temporal polarization evolution of the pulse during the initial stage of transmission. The asymmetric refractive index profile concentrates the pulse energy in the lower edge region of the waveguide core, while the birefringent interface causes a pre-defined spatiotemporal overlap of the optical fields along the pulse's leading and trailing edges. Spatiotemporal synchronization preprocessing establishes predictable initial conditions for subsequent dynamic compensation, avoiding the spatiotemporal coupling mismatch problem caused by traditional single-dimensional control. By utilizing the spatial selectivity of grating scattering and the dynamic tuning capability of phase change materials, it achieves synergistic suppression of nonlinear effects and dispersion distortion. The grating period is designed based on the non-uniform distribution of the pulse, resulting in stronger scattering loss in the high-power region. The phase change material is controlled by a real-time feedback electric field sequence. Adjusting the refractive index compensates for phase distortion while suppressing spectral broadening; the combination of spatially selective loss and dynamic refractive index compensation breaks through the traditional uniform compensation method's trade-off between suppressing nonlinearity and dispersion; a combination mechanism of dispersion truncation and absorption edge effect is adopted to forcibly lock the pulse's temporal and frequency domain morphology; the dispersion truncation effect formed by the oxide interface layer terminates the pulse's continuous evolution trend, while the absorption edge of the polymer coating filters out spectral sidelobe components; the two work synergistically in the spatiotemporal dimensions, enabling the pulse to maintain self-similar characteristics while obtaining a highly stable output shape and spectral characteristics. Attached Figure Description

[0006] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0007] In the attached diagram: Figure 1 This is a flowchart of the self-similar evolution method of femtosecond pulses in chip-scale waveguides provided in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the self-similar evolution method of femtosecond pulses in chip-scale waveguides provided in Embodiment 1 of the present invention; Figure 3 This is a diagram illustrating the process by which the asymmetric refractive index profile induces a non-uniform distribution of the femtosecond pulse electric field intensity within the waveguide cross-section, as provided in Embodiment 2 of the present invention. Figure 4 This is a process diagram of dynamic adjustment based on the real-time monitored pulse spectrum broadening provided in Embodiment 3 of the present invention; Figure 5 This is a process diagram of curing the pulse time-domain envelope shape determined by the dispersion cutoff effect, as provided in Embodiment 9 of the present invention. Figure 6 This relates to the self-similar evolution system of femtosecond pulses in chip-scale waveguides provided in Embodiment 10 of the present invention. Figure 7A block diagram of the electronic device provided by the present invention; Figure 8 A block diagram of a computer-readable storage medium provided for this invention.

[0008] Reference numerals: 1; 2; 4, Central Processing Unit / Microprocessor / Main Control Chip; 5, Storage Medium; 6, Data Bus; 7, Input / Output Bus / External Bus / Device Bus; 8, Display; 9, Input / Output Device; 10, Computer-Readable Instructions; 11, Non-Transitory Computer-Readable Storage Medium. Detailed Implementation

[0009] The technical solutions of the present invention will now be described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0010] Hereinafter, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0011] In this invention, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed mechanical connection, a detachable mechanical connection, or an integral part; or, "connection" can be a direct connection or an indirect connection through an intermediate medium. Furthermore, unless otherwise explicitly specified and limited, the term "coupling" should be interpreted broadly. For example, "coupling" can be a direct electrical connection, such as physical contact and electrical conduction between two components; it can also be understood as an electrical connection between different components in a circuit structure through physical lines capable of transmitting electrical signals, such as copper foil or wires on a printed circuit board (PCB), to transmit electrical signals; or, "coupling" can be an indirect electrical connection between two components through an intermediate medium; or, "coupling" can be an electrical connection between two components in a non-contact manner, such as an electrical connection between two components using capacitive coupling to transmit electrical signals. In this embodiment of the invention, directional terms such as "up," "down," "left," and "right" may be defined relative to the indicated placement of components in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and may change accordingly based on variations in the placement of components in the accompanying drawings. 0012. Example 1: As... Figure 1As shown, this embodiment of the invention provides a self-similar evolution method for femtosecond pulses in a chip-scale waveguide, comprising the following steps: Step S100: The input femtosecond pulse is introduced into the chip waveguide inlet section composed of birefringent heteromaterial; the upper cladding of the inlet waveguide is composed of first-doped silicon dioxide treated by ion beam tilting implantation, and the lower cladding is composed of undoped second silicon dioxide, forming an asymmetric refractive index profile; the chip waveguide inlet section performs synchronous preprocessing on the spatiotemporal characteristics of the pulse; the asymmetric refractive index profile induces the femtosecond pulse electric field intensity to form a non-uniform distribution in the waveguide cross section, and its intensity peak region is constrained to the lower edge of the waveguide core near the lower cladding; the birefringence effect at the interface of the birefringent heteromaterial causes the group velocity of different polarization components in the pulse to separate, resulting in a preset spatiotemporal overlap of the optical fields at the leading and trailing edges of the femtosecond pulse in the early stage of transmission; thus, an initialization pulse with internal spatiotemporal correlation is obtained; Step S200: Initialize the distributed parameter dynamic compensation array in the middle section of the waveguide of the pulse input chip. The distributed parameter dynamic compensation array is composed of a series of micro-units periodically arranged in the waveguide core layer. Each micro-unit is composed of a subwavelength grating structure formed by laser direct writing and a thin layer of electrically controlled phase change material surrounding it. The period of the subwavelength grating structure is determined by the non-uniform intensity distribution information of the femtosecond pulse in the front section, making its scattering effect on the light field in the pulse peak region stronger than that in the edge region. The crystal state of the electrically controlled phase change material thin layer is controlled by the gradient electric field sequence applied externally and dynamically adjusted according to the pulse spectrum broadening degree monitored in real time. When the pulse spectrum broadening exceeds the threshold, the gradient electric field drives the electrically controlled phase change material to undergo a partial transition from amorphous to crystalline state, changing the local effective refractive index of the grating structure, thereby specifically enhancing the scattering loss in the pulse peak region, forming synchronous dynamic compensation for nonlinearity and dispersion, and obtaining an intermediate pulse with a stable spectral width and phase distribution. Step S300: The intermediate pulse is input to the output coupler at the end of the waveguide; the main body of the coupler is a gradually expanding tapered waveguide, the sidewalls of which are made of silicon-germanium alloy after high-temperature oxidation annealing, forming an oxide interface layer that thickens exponentially with the transmission distance; the increase in the thickness of the oxide interface layer causes the equivalent waveguide dispersion in the tapered region to be sharply enhanced in the transmission direction, forming a dispersion cutoff effect, forcibly terminating the trend of further pulse evolution; the end of the tapered waveguide is connected to the output straight waveguide, the core material of the straight waveguide is the same as the material at the beginning of the tapered waveguide, but the upper and lower claddings of the straight waveguide are replaced with low-loss UV-curable polymers, the low-loss UV-curable polymers at the dispersion cutoff point of the tapered waveguide and the interface of the straight waveguide produce morphological locking of the pulse shape; the locking mechanism originates from the absorption edge effect of the polymer cladding in the pulse frequency band; at the same time, the pulse time-domain envelope shape determined by the dispersion cutoff effect is cured; after the coupler processing, the final output is a femtosecond pulse that maintains self-similar characteristics and has a stable shape and spectrum.

[0012] In the above embodiments, this embodiment achieves efficient self-similar evolution control of femtosecond pulses in chip-level waveguides through multi-step synergistic action; by combining asymmetric waveguide structure with birefringence effect, the spatial intensity distribution and temporal polarization evolution of the pulse are simultaneously regulated in the early stage of pulse transmission. The asymmetric refractive index profile concentrates and confines the pulse energy to the lower edge region of the waveguide core, while the birefringence interface causes a preset spatiotemporal overlap of the optical fields at the leading and trailing edges of the pulse; spatiotemporal synchronization preprocessing establishes predictable initial conditions for subsequent dynamic compensation, avoiding the spatiotemporal coupling mismatch problem caused by traditional single-dimensional control; by utilizing the spatial selectivity of grating scattering and the dynamic tuning capability of phase change materials, synergistic suppression of nonlinear effects and dispersion distortion is achieved; the grating period is designed according to the non-uniform distribution of the pulse, making it generate stronger scattering loss in the high-power region; the phase change material is adjusted by real-time feedback electric field sequence. The refractive index, while suppressing spectral broadening, compensates for phase distortion; the combination of spatially selective loss and dynamic refractive index compensation breaks through the traditional uniform compensation method's trade-off between suppressing nonlinearity and dispersion; a combined mechanism of dispersion truncation and absorption edge effects is employed to forcibly lock the pulse's temporal and frequency domain morphology; the dispersion truncation effect formed by the oxide interface layer terminates the pulse's continuous evolution trend, while the absorption edge of the polymer coating filters out spectral sidelobe components; the two work synergistically in the spatiotemporal dimensions, enabling the pulse to maintain self-similarity while obtaining a highly stable output shape and spectral characteristics (the principle is described in the appendix). Figure 2 ).

[0013] In summary, this embodiment forms a complete control chain from preprocessing and dynamic compensation to final locking through the orderly connection and functional complementarity of three stages. The spatiotemporal correlation established in the preprocessing stage provides an optimization basis for dynamic compensation, the nonlinearity and dispersion distortion suppressed in the dynamic compensation stage creates conditions for final locking, and the locking mechanism ensures the long-term stability of the evolution results. The multi-stage collaborative control method significantly improves the controllability and output quality of femtosecond pulse evolution in integrated waveguides.

[0014] Example 2: Figure 3 As shown, based on Example 1, the process of the asymmetric refractive index profile inducing a non-uniform distribution of the femtosecond pulse electric field intensity within the waveguide cross-section in step S100 of this embodiment of the invention specifically includes the following steps: Step S101: The first doped silicon dioxide treated by ion beam tilting implantation forms the upper cladding layer. This process generates a doping concentration gradient that varies with depth inside the material. The doping concentration gradient is converted into a continuous refractive index gradient from top to bottom. At the same time, the undoped second silicon dioxide serves as the lower cladding layer. The continuous refractive index gradient of the upper cladding layer and the uniform refractive index of the lower cladding layer work together to form an asymmetric refractive index profile. Step S102: The asymmetric refractive index profile acts on the incident femtosecond pulse, resulting in mode field mismatch. The mismatch causes the pulse's optical field to be unable to expand symmetrically within the waveguide core, and the optical field energy is forced to be squeezed towards the lower cladding. The squeezing process of the optical field energy further interacts with the uniform high refractive index characteristics of the lower cladding. The lower cladding generates a strong localization attraction effect on the squeezed optical field. The localization attraction effect captures and confines most of the optical field energy to a very narrow region near the interface between the waveguide core and the lower cladding. Step S103: After continuous action, compression and constraint processes, the electric field intensity of the femtosecond pulse in the waveguide cross section changes from an initial uniform or symmetrical distribution to a non-uniform distribution in which the intensity peak region is firmly confined to the lower edge of the waveguide core.

[0015] In the above embodiments, an upper cladding with a continuous refractive index gradient is formed by tilted ion beam implantation of the first doped silicon dioxide, and combined with a lower cladding composed of undoped silicon dioxide, an asymmetric refractive index profile is constructed. This profile causes mode field mismatch, forcing the optical energy of the femtosecond pulse to be squeezed towards the lower cladding. The squeezed optical field interacts with the uniform high refractive index characteristics of the lower cladding, generating a strong localization attraction effect, concentrating the optical energy within a narrow region at the interface between the waveguide core and the lower cladding. Ultimately, the electric field intensity of the femtosecond pulse changes from an initial uniform or symmetrical distribution within the waveguide cross-section to a non-uniform distribution where the peak intensity region is firmly confined to the lower edge of the waveguide core, achieving efficient localization and stable guidance of the optical energy.

[0016] Example 3: As Figure 4 As shown, based on Example 1, the process of dynamically adjusting according to the pulse spectrum broadening degree monitored in real time in step S200 of this embodiment of the invention specifically includes the following steps: Step S201: The intermediate pulse transmitted through the waveguide is monitored in real time using a spectrum sidelobe probe array integrated into the waveguide sidewall; each probe unit in the spectrum sidelobe probe array receives weak leakage light from the waveguide, and the weak leakage light carries the spectrum information of the pulse; the weak leakage light received by each probe unit is asynchronously optically sampled, and the fragments of spectrum information of the intermediate pulse at different times are mapped into a two-dimensional light intensity distribution map. Step S202: The two-dimensional light intensity distribution map is captured by the high-speed photoelectric conversion array and converted into a corresponding charge distribution map; in the charge distribution map, the width of the charge accumulation region corresponds to the broadening degree of the monitored pulse spectrum; a voltage pattern with spatially varying amplitude is generated according to the broadening degree. Step S203: A voltage pattern is applied to the interdigitated electrode pair on the back side of the electrically controlled phase change material thin layer. At a local position corresponding to the pulse peak light field region inside the phase change material thin layer, an electric field sequence with amplitude distributed according to a preset gradient is generated. The gradient electric field sequence acts on the electrically controlled phase change material, driving the atomic arrangement inside it to undergo a ordered transformation from an amorphous state to a crystalline state. The regional change in the crystalline state of the electrically controlled phase change material leads to a corresponding local change in refractive index, completing the dynamic adjustment of the local effective refractive index of the grating structure according to the pulse spectrum broadening degree monitored in real time.

[0017] In the above embodiments, this embodiment achieves real-time compensation for the pulse spectrum broadening by integrating monitoring and feedback control mechanisms; it uses a spectral sidelobe probe array on the waveguide sidewall to capture the leakage light signal during pulse transmission, and maps the temporal spectrum information into a two-dimensional light intensity distribution through asynchronous optical sampling, thereby achieving spatiotemporal analysis of the spectrum characteristics; it converts the light intensity distribution into a charge distribution map through a high-speed photoelectric conversion array, quantifies the spectrum broadening based on the width of the charge accumulation region, and generates a voltage pattern with spatial modulation characteristics; the voltage pattern acts on the interdigitated electrodes of the electrically controlled phase change material layer, generating a gradient-distributed electric field sequence, inducing the phase change material to undergo local crystallization transformation; the regional reconstruction of the crystal structure causes a corresponding change in refractive index, thereby dynamically adjusting the local effective refractive index of the grating structure.

[0018] In summary, this embodiment achieves closed-loop control from spectrum monitoring and electrical signal generation to refractive index modulation, ultimately achieving real-time adaptive compensation for pulse spectrum broadening and improving the time-frequency stability of the pulse during waveguide transmission.

[0019] Example 4: Based on Example 3, the process of converting the two-dimensional light intensity distribution map in step S202 of this embodiment of the invention specifically includes the following steps: Step S2021: The two-dimensional light intensity distribution map is projected onto the photosensitive plane of the high-speed photoelectric conversion array. The high-speed photoelectric conversion is composed of regularly arranged pixel units, and each pixel unit integrates a photoelectric conversion junction based on a double Schottky barrier structure. The double Schottky barrier structure receives and acts on the incident two-dimensional light intensity distribution map, converting the light intensity information at each position in the two-dimensional light intensity distribution map into a corresponding number of non-equilibrium charge carriers. The rate of charge carrier generation is proportional to the local light intensity. Step S2022: Within each pixel unit, the generated charge carriers are collected by the floating gate tunneling node below it; within a preset extremely short integration time, the floating gate tunneling node converts the injected charge carriers into an equivalent charge on the floating gate through the field-assisted tunneling effect. Step S2023: After all pixel units in the high-speed photoelectric conversion array complete charge conversion and storage, the amount of charge stored on each floating gate node together constitutes a space charge density distribution map; in the space charge density distribution map, the physical width of the charge accumulation region corresponds to the pulse spectrum broadening degree mapped by the two-dimensional light intensity distribution map.

[0020] In the above embodiments, after the two-dimensional light intensity distribution is projected onto the high-speed photoelectric conversion array, the light intensity at each position is linearly converted into non-equilibrium charge carriers through the photoelectric conversion junction of the double Schottky barrier structure, thereby realizing the accurate mapping of light intensity information to the number of charge carriers.

[0021] Subsequently, the floating gate tunneling node collects carriers and converts them into equivalent charge stored in the floating gate through the field-assisted tunneling effect within an extremely short integration time, completing the quantitative transfer from optical signal to charge signal. Finally, the stored charge of all pixel units together forms a spatial charge density distribution map, in which the physical width of the charge accumulation region directly reflects the spectral broadening characteristics of the original optical pulse, thereby realizing the end-to-end transformation from light intensity distribution to charge distribution, and then to spectral feature extraction.

[0022] Example 5: Based on Example 4, the process of converting the light intensity information at each position in the two-dimensional light intensity distribution map into a corresponding number of non-equilibrium carriers in step S2021 of this embodiment of the invention specifically includes the following steps: Step S20211: A two-dimensional light intensity distribution map is applied to the double Schottky barrier structure within the pixel unit; the double Schottky barrier structure consists of a first metal layer and a second metal layer deposited on both sides of the intrinsic layer of the semiconductor, and the two metal layers have different work functions; incident light with different photon energies passes through the first metal layer and undergoes internal photoemission at the interface between the first metal layer and the intrinsic layer; the energy of the photon is transferred to the bound electrons at the interface, and after gaining energy, the bound electrons cross the first Schottky barrier and are injected into the intrinsic layer to become the first type of non-equilibrium carriers; Step S20212: The remaining photons that penetrate the intrinsic layer trigger secondary internal photoemission at the interface between the second metal layer and the intrinsic layer, generating and injecting second-type non-equilibrium carriers. The injection location is spatially separated from the first-type carriers within the intrinsic layer. Step S20213: Under the influence of a preset bias electric field inside the intrinsic layer, the first and second types of non-equilibrium carriers drift in opposite directions. During their movement, they collide with the lattice inside the intrinsic layer and are ionized. The collisional ionization process generates additional carrier pairs. Through the continuous action of internal photoemission and collisional ionization, the light intensity information at each position in the two-dimensional light intensity distribution map is converted into a non-equilibrium carrier group whose quantity is multiplied and whose spatial position corresponds to the non-equilibrium carrier group.

[0023] In the above embodiments, this embodiment uses a dual Schottky barrier structure to perform internal photoemission at the first metal layer-intrinsic layer interface and the second metal layer-intrinsic layer interface, respectively, to convert the incident light photon energy into two types of spatially separated non-equilibrium carriers. Under the action of a bias electric field, the carriers drift in a direction and induce collisional ionization, thereby multiplying the number of carriers. Finally, the spatial and intensity information of the two-dimensional light intensity distribution is synchronously converted into a non-equilibrium carrier distribution with corresponding spatial positions and multiplied numbers, completing the efficient conversion and enhancement of optical information to electric carrier information.

[0024] Example 6: Based on Example 5, the process of the first and second types of non-equilibrium carriers acting under the preset bias electric field inside the intrinsic layer in step S20213 of this embodiment of the invention specifically includes the following steps: Step S202131: Based on the work function difference between the first metal layer and the second metal layer, and combined with the vertical gradient doping region, an internal electric field pointing inward is formed in a local region of the intrinsic layer near the first metal layer; at the same time, another internal electric field pointing outward is formed in a local region of the intrinsic layer near the second metal layer. Step S202132: Type I non-equilibrium carriers enter and are located in a local region near the first metal layer. They are affected by the built-in electric field pointing into the layer and gain a drift displacement along the direction of the electric field, resulting in a drift motion towards the depth of the intrinsic layer. Type II non-equilibrium carriers enter and are located in a local region near the second metal layer. They are affected by the built-in electric field pointing out of the layer and gain a drift displacement along the direction of the electric field, resulting in a drift motion towards the shallower area outside the intrinsic layer. Step S202133: The built-in electric fields of the two local regions are in opposite directions, and act on the drift momentum of the first and second types of non-equilibrium carriers in opposite directions; the two types of carrier groups therefore begin to drift in opposite directions to separate spatially.

[0025] In the above embodiment, this embodiment utilizes the work function difference between the first metal layer and the second metal layer, combined with the longitudinal gradient doping region, to form an internal electric field with opposite directions in a local region near the two metal layers of the intrinsic layer; the first type of non-equilibrium carriers are subjected to the electric field pointing inward in the local region near the first metal layer, and gain momentum to drift deeper into the intrinsic layer; the second type of non-equilibrium carriers are subjected to the electric field pointing outward in the local region near the second metal layer, and gain momentum to drift shallower outside the intrinsic layer; the two types of carriers drift in opposite directions under the action of electric fields in opposite directions, realizing the effective separation of the carrier group in space.

[0026] Example 7: Based on Example 6, the process of combining the work function difference with the longitudinal gradient doping region in step S202131 of this embodiment of the invention specifically includes the following steps: Step S2021311: The first metal layer and the second metal layer are deposited on both sides of the intrinsic semiconductor layer. The absolute value of the work function of the first metal layer is greater than the absolute value of the work function of the second metal layer, forming an inherent work function difference between the two. The work function difference induces an initial contact potential difference at both ends of the undoped intrinsic layer. The direction of the initial contact potential difference is from the first metal layer with a larger absolute value of work function to the second metal layer with a smaller absolute value of work function. Step S2021312: During the fabrication of the semiconductor intrinsic layer, a vertical gradient doping region is introduced through ion implantation and rapid thermal annealing processes. The characteristic feature is that the net ionized donor concentration is highest near the interface of the first metal layer and decreases linearly and continuously along the layer thickness towards the interface of the second metal layer until the intrinsic state is reached. The vertical gradient doping region acts on the fixed charge distribution within the intrinsic layer. The high-concentration net ionized donor region contributes a corresponding net positive space charge, and the density of the net positive space charge decreases accordingly with the monotonically decreasing net ionized donor concentration. Step S2021313: The initial contact potential difference and the gradient-distributed net positive space charge work together to modulate the net space charge distribution inside the intrinsic layer, partially compensating for the original space charge field near the first metal layer region, and simultaneously superimposing and enhancing the space charge field near the second metal layer region; forming a non-uniform electric field with gradually decreasing intensity from the middle of the intrinsic layer towards the interface of the first metal layer, pointing inward; and simultaneously forming a non-uniform electric field with gradually increasing intensity from the middle of the intrinsic layer towards the interface of the second metal layer, pointing outward.

[0027] In the above embodiment, this embodiment utilizes the inherent work function difference between the first metal layer and the second metal layer to induce an initial contact potential difference at both ends of the intrinsic layer, with the direction pointing from the first metal layer with a larger absolute value of work function to the second metal layer with a smaller absolute value of work function. A longitudinal gradient doping region is introduced into the intrinsic layer through ion implantation and rapid thermal annealing processes, so that the net ionized donor concentration is highest near the interface of the first metal layer and continuously decreases linearly along the layer thickness towards the interface of the second metal layer until the intrinsic state is reached. The gradient doping region generates a net positive space charge distribution that decreases monotonically with the concentration gradient. The initial contact potential difference and the net positive space charge of this gradient distribution modulate the net space charge distribution inside the intrinsic layer, partially compensating for the original space charge field near the region of the first metal layer, and simultaneously superimposing and enhancing the space charge field near the region of the second metal layer. Finally, a non-uniform electric field with gradually weakening intensity from the middle of the layer towards the interface and pointing inward is formed in a local region of the intrinsic layer near the first metal layer, and a non-uniform electric field with gradually increasing intensity from the middle of the layer towards the interface and pointing outward is formed in a local region near the second metal layer.

[0028] Example 8: Based on Example 7, the process of superimposing and enhancing the space charge field near the second metal layer region in step S2021313 of this embodiment of the invention specifically includes the following steps: Step S20213131: The initial contact potential difference induces an initial space charge distribution within the intrinsic layer. The initial space charge distribution is characterized by the formation of a thin layer of negative space charge in the region near the first metal layer and a thin layer of positive space charge in the region near the second metal layer. Step S20213132: The net positive space charge obtained by the longitudinal gradient distribution has the highest density in the region near the first metal layer; the high density net positive space charge acts on the initial space charge distribution and interacts with the negative space charge thin layer in the region near the first metal layer. Some of the charges in the negative space charge thin layer are neutralized, causing the net negative charge density in the region to decrease; this constitutes partial compensation for the original space charge field in the region near the first metal layer established by the initial contact potential difference. Step S20213133: The net positive space charge density of the gradient distribution is lowest in the region near the second metal layer; the low-density net positive space charge interacts with the thin layer of positive space charge in the region near the second metal layer; the low-density net positive space charge is injected and superimposed on the original thin layer of positive space charge. This superposition process leads to an increase in the net positive charge density in the region; the increase in charge density constitutes a superposition enhancement of the original space charge field in the region near the second metal layer.

[0029] In the above embodiments, the initial contact potential difference induces an initial space charge distribution within the intrinsic layer, forming a thin layer of negative space charge in the region near the first metal layer and a thin layer of positive space charge in the region near the second metal layer. The net positive space charge with a vertical gradient distribution has the highest density in the region near the first metal layer. The high-density net positive space charge interacts with the thin layer of negative space charge, neutralizing some of the negative charge and reducing the net negative charge density, thus partially compensating for the original space charge field established by the initial contact potential difference in the region near the first metal layer. At the same time, the net positive space charge with a gradient distribution has the lowest density in the region near the second metal layer. The low-density net positive space charge is injected into and superimposed on the original thin layer of positive space charge, resulting in an increase in the net positive charge density, which constitutes a superposition enhancement of the original space charge field in the region near the second metal layer. 0030. Example 9: As Figure 5 As shown, based on Example 1, the process of solidifying the pulse time-domain envelope shape determined by the dispersion cutoff effect in step S300 of this embodiment of the invention specifically includes the following steps: Step S301: The intermediate pulse, after being processed by the dispersion truncation effect, has its temporal envelope shape, which has been forcibly terminated, determined at the end of the tapered waveguide; the intermediate pulse is then introduced into the output straight waveguide; the upper and lower cladding of the output straight waveguide are made of low-loss UV-curable polymer; during the UV curing stage, the low-loss UV-curable polymer is used to form a consistent molecular chain orientation within its polymer crosslinking network by controlling the UV light exposure dose of the wavelength. Step S302: The molecular chain orientation structure causes the polymer material to produce a sharp absorption edge in the optical frequency domain; the frequency position of the absorption edge has been set during the material preparation stage to align with the central spectral component corresponding to the pulse time-domain envelope shape determined by the dispersion cutoff effect; when the pulse enters the straight waveguide section wrapped by the low-loss UV-curable polymer cladding, the absorption edge effect of the low-loss UV-curable polymer cladding affects the pulse spectrum; the spectral component on the high-frequency side of the absorption edge is resonantly absorbed by the polymer molecular chain and converted into heat energy for dissipation; the spectral component on the low-frequency side of the absorption edge passes through with low loss. Step S303: After frequency-selective absorption processing, sidelobe and noise frequency components in the pulse spectrum that are unrelated to or contrary to the envelope shape determined by dispersion truncation are filtered out, while the main lobe frequency components corresponding to the core envelope shape are completely preserved; through selective attenuation of spectral components by absorption edge effect, the pulse time-domain envelope shape uniquely determined by dispersion truncation effect no longer changes during transmission, thus completing the solidification of the time-domain envelope shape.

[0030] In the above embodiment, the intermediate pulse processed by the dispersion truncation effect has its temporal envelope shape forcibly terminated at the end of the tapered waveguide, and is then introduced into the output straight waveguide with a low-loss UV-curable polymer as the upper and lower cladding layers. During the UV curing stage, the polymer is oriented with consistent molecular chain orientation by controlling the exposure dose, thereby generating a sharp absorption edge in the optical frequency domain. The frequency position of the absorption edge is set during the material preparation stage and aligned with the center spectral component corresponding to the pulse temporal envelope shape determined by the dispersion truncation effect. When the pulse enters the straight waveguide... During this period, the absorption edge effect of the polymer cladding acts on the pulse spectrum, causing the spectral components on the high-frequency side of the absorption edge to be resonantly absorbed and converted into heat dissipation, while the spectral components on the low-frequency side pass through with low loss. After this frequency-selective absorption process, sidelobe and noise frequency components that are unrelated to or contrary to the core envelope shape in the pulse spectrum are filtered out, while the main lobe frequency components are completely preserved. Through the selective attenuation of spectral components by the absorption edge effect, the pulse time-domain envelope shape, which is uniquely determined by the dispersion truncation effect, no longer changes during transmission, thus completing the solidification of the time-domain envelope shape.

[0031] Example 10: As Figure 6As shown, based on Embodiments 1-9, the self-similar evolution system of femtosecond pulses in a chip-scale waveguide provided by this invention includes: a spatiotemporal correlation processing module 1, configured to guide the input femtosecond pulse into a chip waveguide inlet segment composed of a birefringent heteromaterial; the upper cladding of the inlet waveguide is composed of first-doped silicon dioxide treated by ion beam tilting implantation, and the lower cladding is composed of undoped second silicon dioxide, forming an asymmetric refractive index profile; the chip waveguide inlet segment synchronously preprocesses the spatiotemporal characteristics of the pulse; the asymmetric refractive index profile induces the femtosecond pulse electric field intensity to form a non-uniform distribution in the waveguide cross-section, and its intensity peak region is constrained to the lower edge of the waveguide core near the lower cladding; the birefringence effect at the interface of the birefringent heteromaterial causes the group velocity of different polarization components in the pulse to separate, resulting in a preset spatiotemporal overlap of the optical fields at the leading and trailing edges of the femtosecond pulse in the early stage of transmission; thus obtaining an initial pulse with internal spatiotemporal correlation. The dynamic compensation synchronization module 2 is configured to initialize the distributed parameter dynamic compensation array in the middle section of the waveguide of the pulse input chip. The distributed parameter dynamic compensation array consists of a series of micro-units periodically arranged in the waveguide core layer. Each micro-unit is composed of a subwavelength grating structure formed by laser direct writing and a thin layer of electrically controlled phase change material surrounding it. The period of the subwavelength grating structure is determined by the non-uniform intensity distribution information of the femtosecond pulse in the front section, making its scattering effect on the light field in the pulse peak region stronger than that in the edge region. The crystal state of the electrically controlled phase change material thin layer is controlled by the gradient electric field sequence applied externally and dynamically adjusted according to the pulse spectrum broadening degree monitored in real time. When the pulse spectrum broadening exceeds the threshold, the gradient electric field drives the electrically controlled phase change material to undergo a partial transition from amorphous to crystalline state, changing the local effective refractive index of the grating structure, thereby specifically enhancing the scattering loss in the pulse peak region, forming synchronous dynamic compensation for nonlinearity and dispersion, and obtaining an intermediate pulse with a stable spectral width and phase distribution. The coupling processing module 3 is configured to input the intermediate pulse into the output coupler at the end of the waveguide. The main body of the coupler is a gradually expanding tapered waveguide. The sidewalls of its tapered region are made of silicon-germanium alloy that has undergone high-temperature oxidation annealing, forming an oxide interface layer that thickens exponentially with the transmission distance. The increase in the thickness of the oxide interface layer causes the equivalent waveguide dispersion in the tapered region to be sharply enhanced in the transmission direction, forming a dispersion cutoff effect, which forcibly terminates the trend of further pulse evolution. The end of the tapered waveguide is connected to the output straight waveguide. The core material of the straight waveguide is the same as that of the starting end of the tapered waveguide, but the upper and lower claddings of the straight waveguide are replaced with low-loss UV-curable polymers. The low-loss UV-curable polymers form a shape lock for the pulse shape at the dispersion cutoff point of the tapered waveguide and the interface of the straight waveguide. The locking mechanism originates from the absorption edge effect of the polymer cladding in the pulse frequency band. At the same time, the pulse time-domain envelope shape determined by the dispersion cutoff effect is cured. After processing by the coupler, the final output is a femtosecond pulse that maintains self-similar characteristics and has a stable shape and spectrum.

[0032] In the above embodiments, the spatiotemporal correlation processing module of this embodiment constructs the spatiotemporal correlation within the pulse in the early stage of transmission through the synergistic effect of the asymmetric waveguide structure and the birefringent heteromaterial. The asymmetric refractive index profile confines the pulse energy to the lower edge of the waveguide core, and combined with the birefringence effect, induces different polarization components to generate a preset group velocity separation, forming an initialization pulse with specific spatiotemporal overlap characteristics. The dynamic compensation synchronization module realizes real-time suppression of nonlinearity and dispersion based on a distributed parameter array. The subwavelength grating structure is periodically designed according to the pulse intensity distribution, so that its scattering loss is positively correlated with the light field intensity. Combined with the refractive index dynamic control mechanism of the electrically controlled phase change material, when the spectral broadening exceeds the threshold, the crystallization transition driven by the gradient electric field can specifically enhance the scattering loss in the peak region, forming dynamic compensation for the pulse core evolution region, thereby suppressing spectral broadening and stabilizing the phase distribution. The coupling processing module achieves pulse evolution termination and shape solidification through the dispersion cutoff effect of the gradually expanding tapered waveguide and the morphology locking mechanism of the polymer cladding. The thickness of the oxide interface layer increases exponentially with the transmission distance, which leads to a sharp increase in dispersion in the tapered region, forcibly terminating the pulse evolution trend. The low-loss UV-curable polymer uses the absorption edge effect at the interface to lock the time-domain envelope shape determined by the dispersion cutoff, and finally outputs a femtosecond pulse with stable self-similar characteristics.

[0033] In summary, the three-stage processing chain of spatiotemporal initialization-dynamic compensation-evolution termination in this embodiment realizes the self-similar evolution control of femtosecond pulses at the chip scale, while ensuring the time-frequency stability and shape fidelity of the output pulses.

[0034] Figure 7 A block diagram of an exemplary electronic device suitable for implementing embodiments of the present invention is shown.

[0035] The electronic device may include a central processing unit / microprocessor / main control chip 4; and a storage medium 5 coupled to the central processing unit / microprocessor / main control chip 4 and storing computer-executable instructions therein for performing the steps of various methods of embodiments of the present invention when executed by the processor.

[0036] The central processing unit / microprocessor / main control chip 4 may include, but is not limited to, one or more processors or microprocessors.

[0037] Storage medium 5 may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, computer storage media (e.g., hard disk, floppy disk, solid-state drive, removable disk, Blu-ray disc, etc.).

[0038] In addition, the electronic device may include (but is not limited to) a data bus 6, an input / output bus / external bus / device bus 7, a display 8, and input / output devices 9 (e.g., keyboard, mouse, speaker, etc.).

[0039] The central processing unit / microprocessor / main control chip 4 can communicate with external devices (8, 9, etc.) via wired or wireless networks (not shown) through the input / output bus / external bus / device bus 7.

[0040] The storage medium 5 may also store at least one computer-executable instruction for performing the steps of various functions and / or methods in the embodiments described herein when the central processing unit / microprocessor / main control chip 4 is running.

[0041] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0042] Figure 8 A schematic diagram of a computer-readable storage medium according to an embodiment of the present invention is shown.

[0043] like Figure 8 As shown, the non-transitory computer-readable storage medium 11 stores instructions, such as computer-readable instructions 10. When the computer-readable instructions 10 are executed by a processor, the various methods described above can be performed. The non-transitory computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Non-transitory non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, the non-transitory computer-readable storage medium 11 can be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions 10 stored on the non-transitory computer-readable storage medium 11, the various methods described above can be performed.

[0044] In the embodiments provided by this invention, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between systems or units may be electrical, mechanical, or other forms.

[0045] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0046] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0047] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods of the various embodiments of this invention through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the self-similar evolution of femtosecond pulses in a chip-scale waveguide, characterized in that, Includes the following steps: The distributed parameter dynamic compensation array in the middle section of the waveguide of the initial pulse input chip is initialized. The subwavelength grating structure has a stronger scattering effect on the light field in the pulse peak region than in the edge region. The crystal state of the electrically controlled phase change material thin layer is controlled by the externally applied gradient electric field sequence and dynamically adjusted according to the pulse spectrum broadening degree monitored in real time. When the pulse spectrum broadens beyond the threshold, the gradient electric field drives the electrically controlled phase change material to undergo a partial transition from amorphous to crystalline state, changing the local effective refractive index of the grating structure, forming synchronous dynamic compensation for nonlinearity and dispersion, and obtaining an intermediate pulse with a stable spectral width and phase distribution. The intermediate pulse is input to the output coupler at the end of the waveguide; the tapered waveguide end is connected to the output straight waveguide, and the low-loss UV-cured polymer generates morphological locking of the pulse shape at the dispersion cutoff point of the tapered waveguide and the interface of the straight waveguide; at the same time, the pulse time-domain envelope shape determined by the dispersion cutoff effect is cured. After being processed by the coupler, the output is a femtosecond pulse that retains its self-similar characteristics and has a stable shape and spectrum.

2. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 1, characterized in that, The process of dynamically adjusting based on the real-time monitored pulse spectrum broadening includes the following steps: A spectrum sidelobe probe array integrated into the waveguide sidewall is used to monitor the intermediate pulses in real time. The weak leakage light received by each probe unit is asynchronously optically sampled by a time-frequency mapping module, which maps the spectral information fragments of the intermediate pulse at different times into a two-dimensional light intensity distribution map. The two-dimensional light intensity distribution map is captured by a high-speed photoelectric conversion array and converted into a corresponding charge distribution map; In a charge distribution diagram, a voltage pattern with spatially varying amplitude is generated based on the degree of widening. A voltage pattern is applied to the interdigitated electrode pair on the back side of the electrically controlled phase change material thin layer. At a local position within the phase change material thin layer corresponding to the pulse peak light field region, an electric field sequence with amplitude distributed according to a preset gradient is generated. The gradient electric field sequence acts on the electrically controlled phase change material, driving the atomic arrangement inside it to undergo a ordered transformation from an amorphous state to a crystalline state. The regional change in the crystalline state of the electrically controlled phase change material leads to a corresponding local change in refractive index, thus completing the dynamic adjustment of the local effective refractive index of the grating structure based on the pulse spectrum broadening degree monitored in real time.

3. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 2, characterized in that, The process of converting to the corresponding charge distribution map includes the following steps: A two-dimensional light intensity distribution map is projected onto the photosensitive plane of a high-speed photoelectric conversion array. The high-speed photoelectric conversion is composed of regularly arranged pixel units, and each pixel unit integrates a photoelectric conversion junction based on a double Schottky barrier structure. The double Schottky barrier structure receives and acts on the incident two-dimensional light intensity distribution map, converting the light intensity information at each position in the two-dimensional light intensity distribution map into a corresponding number of non-equilibrium charge carriers. The rate of charge carrier generation is proportional to the local light intensity. Within each pixel unit, the generated charge carriers are collected by the floating gate tunneling node below it; within a preset extremely short integration time, the floating gate tunneling node converts the injected charge carriers into an equivalent charge on the floating gate through the field-assisted tunneling effect. After all pixel units in a high-speed photoelectric conversion array complete charge conversion and storage, the amount of charge stored on each floating gate node together constitutes a space charge density distribution map; in the space charge density distribution map, the physical width of the charge accumulation region corresponds to the pulse spectrum broadening degree mapped by the two-dimensional light intensity distribution map.

4. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 3, characterized in that, The process of converting the light intensity information at each location in a two-dimensional light intensity distribution map into a corresponding number of non-equilibrium charge carriers includes the following steps: Two-dimensional light intensity distribution map is applied to the double Schottky barrier structure within the pixel unit; incident light with different photon energies passes through the first metal layer of the double Schottky barrier structure and undergoes internal photoemission at the interface between the first metal layer and the intrinsic layer. The energy of the photon is transferred to the bound electron at the interface. After gaining energy, the bound electron crosses the first Schottky barrier and is injected into the intrinsic layer to become a type I non-equilibrium carrier. The remaining photons that penetrate the intrinsic layer trigger secondary internal photoemission at the interface between the second metal layer and the intrinsic layer, generating and injecting second-type non-equilibrium carriers. The injection location is spatially separated from the first-type carriers within the intrinsic layer. Under the influence of a pre-set bias electric field within the intrinsic layer, the first and second types of non-equilibrium carriers drift in opposite directions. During their movement, they collide with the lattice within the intrinsic layer, resulting in ionization and generating additional carrier pairs. Through the continuous action of internal photoemission and collisional ionization, the light intensity information at each location in the two-dimensional light intensity distribution map is converted into a group of non-equilibrium carriers whose quantity is multiplied and whose spatial location corresponds to the non-equilibrium carrier group.

5. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 4, characterized in that, The process by which type I and type II non-equilibrium carriers are acted upon by a pre-set bias electric field within the intrinsic layer includes the following steps: Based on the work function difference between the first metal layer and the second metal layer, and combined with the vertical gradient doping region, an internal electric field pointing inward is formed in a local region of the intrinsic layer near the first metal layer; at the same time, another internal electric field pointing outward is formed in a local region of the intrinsic layer near the second metal layer. Type I non-equilibrium carriers enter and reside in a local region near the first metal layer. They are affected by the built-in electric field pointing into the layer and gain drift momentum along the direction of the electric field, resulting in drift motion towards the depth of the intrinsic layer. Type II non-equilibrium carriers enter and reside in a local region near the second metal layer. They are affected by the built-in electric field pointing outward from the layer and gain drift momentum along the direction of the electric field, resulting in drift motion towards the shallower area outside the intrinsic layer. The built-in electric fields in the two local regions are in opposite directions, and the drift momentum of the first and second types of non-equilibrium carriers is in opposite directions respectively; the two types of carrier groups therefore begin to drift and separate in space in opposite directions.

6. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 5, characterized in that, The process of combining the work function difference with the longitudinal gradient doping region includes the following steps: The first metal layer and the second metal layer are deposited on the two sides of the intrinsic semiconductor layer. The absolute value of the work function of the first metal layer is greater than the absolute value of the work function of the second metal layer, forming an inherent work function difference between the two. The work function difference induces an initial contact potential difference at both ends of the undoped intrinsic layer. The direction of the initial contact potential difference is from the first metal layer with the larger absolute value of the work function to the second metal layer with the smaller absolute value of the work function. During the fabrication of the semiconductor intrinsic layer, a vertically gradient doped region is introduced through ion implantation and rapid thermal annealing processes. The characteristics are that the net ionized donor concentration is highest near the interface of the first metal layer and decreases linearly and continuously along the layer thickness towards the interface of the second metal layer until the intrinsic state; the longitudinal gradient doping region acts on the fixed charge distribution inside the intrinsic layer; the high concentration net ionized donor region contributes the corresponding net positive space charge, and the density of net positive space charge decreases accordingly with the monotonically decreasing net ionized donor concentration. The initial contact potential difference and the gradient-distributed net positive space charge work together to modulate the net space charge distribution inside the intrinsic layer, partially compensating for the original space charge field near the first metal layer region, and simultaneously superimposing and enhancing the space charge field near the second metal layer region. A non-uniform electric field is formed, with its intensity gradually decreasing from the middle of the intrinsic layer towards the interface of the first metal layer, and its direction pointing into the layer; at the same time, a non-uniform electric field is formed, with its intensity gradually increasing from the middle of the intrinsic layer towards the interface of the second metal layer, and its direction pointing outward.

7. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 6, characterized in that, The process of superimposing and enhancing the space charge field near the second metal layer includes the following steps: The initial contact potential difference induces an initial space charge distribution within the intrinsic layer. The initial space charge distribution is characterized by the formation of a thin layer of negative space charge in the region near the first metal layer and a thin layer of positive space charge in the region near the second metal layer. The net positive space charge density of the obtained longitudinal gradient distribution is highest in the region near the first metal layer. The high-density net positive space charge acts on the initial space charge distribution and interacts with the negative space charge thin layer near the first metal layer region. Some of the charges in the negative space charge thin layer are neutralized, causing the net negative charge density of the region to decrease; thus constituting partial compensation for the original space charge field near the first metal layer region established by the initial contact potential difference. The net positive space charge density of the gradient distribution is lowest in the region near the second metal layer; the low-density net positive space charge interacts with the thin layer of positive space charge in the region near the second metal layer; the low-density net positive space charge is injected and superimposed into the original thin layer of positive space charge; resulting in an increase in the net positive charge density in the region; the increase in charge density constitutes a superposition enhancement of the original space charge field in the region near the second metal layer.

8. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 1, characterized in that, The process of solidifying the pulse time-domain envelope shape determined by the dispersion cutoff effect includes the following steps: The intermediate pulse, after being processed by the dispersion truncation effect, has its time-domain envelope shape, which has been forcibly terminated, determined at the end of the tapered waveguide; the intermediate pulse is then introduced into the output straight waveguide; the upper and lower cladding of the output straight waveguide is made of low-loss UV-cured polymer. In the UV curing stage, low-loss UV-curable polymers achieve consistent molecular chain orientation within their polymer crosslinking network by controlling the UV light exposure dose at a specific wavelength. The molecular chain orientation structure causes a sharp absorption edge in the optical frequency domain of the polymer material. The frequency position of the absorption edge is set during the material preparation stage to align with the central spectral component corresponding to the pulse time-domain envelope shape determined by the dispersion cutoff effect. When the pulse enters the straight waveguide section wrapped by the low-loss UV-curable polymer cladding, the absorption edge effect of the low-loss UV-curable polymer cladding affects the pulse spectrum. The spectral component on the high-frequency side of the absorption edge is resonantly absorbed by the polymer molecular chain and converted into heat energy for dissipation. The spectral component on the low-frequency side of the absorption edge passes through with low loss. After frequency-selective absorption processing, sidelobe and noise frequency components in the pulse spectrum that are unrelated to or contradict the envelope shape determined by dispersion truncation are filtered out, while the main lobe frequency components corresponding to the core envelope shape are completely preserved. Through selective attenuation of spectral components by absorption edge effect, the pulse time-domain envelope shape uniquely determined by dispersion truncation effect no longer changes during transmission, thus completing the solidification of the time-domain envelope shape.

9. The self-similar evolution method of femtosecond pulses in chip-scale waveguides as described in claim 1, characterized in that, It also includes guiding the input femtosecond pulse into a chip wave inlet segment made of birefringent heteromaterial; the chip wave inlet segment performs synchronous preprocessing on the spatiotemporal characteristics of the pulse; the birefringence effect at the interface of the birefringent heteromaterial causes the group velocity of different polarization components in the pulse to be separated, resulting in a preset spatiotemporal overlap of the optical fields at the leading and trailing edges of the femtosecond pulse in the early stage of transmission; thus obtaining an initialization pulse with internal spatiotemporal correlation.

10. A self-similar evolution system for femtosecond pulses in a chip-scale waveguide, used to implement the self-similar evolution method for femtosecond pulses in a chip-scale waveguide as described in any one of claims 1 to 9, characterized in that, include: The spatiotemporal correlation processing module 1 is configured to guide the input femtosecond pulse into a chip waveguide inlet segment composed of a birefringent heteromaterial; the chip waveguide inlet segment performs synchronous preprocessing on the spatiotemporal characteristics of the pulse; the asymmetric refractive index profile induces a non-uniform distribution of the femtosecond pulse electric field intensity within the waveguide cross-section, and its peak intensity region is constrained to the lower edge of the waveguide core near the lower cladding; the birefringence effect at the interface of the birefringent heteromaterial causes the group velocity of different polarization components in the pulse to separate, resulting in a preset spatiotemporal overlap of the optical fields at the leading and trailing edges of the femtosecond pulse in the early stage of transmission; thus obtaining an initialization pulse with internal spatiotemporal correlation. The dynamic compensation synchronization module is configured to dynamically compensate the distributed parameters of the waveguide middle section of the initial pulse input chip. The period of the subwavelength grating structure is determined by the non-uniform intensity distribution information of the femtosecond pulse in the front section, making its scattering effect on the light field in the pulse peak region stronger than that in the edge region. The crystal state of the electrically controlled phase change material thin layer is controlled by the externally applied gradient electric field sequence and dynamically adjusted according to the pulse spectrum broadening degree monitored in real time. When the pulse spectrum broadens beyond the threshold, the gradient electric field drives the electrically controlled phase change material to undergo a partial transition from amorphous to crystalline state, forming synchronous dynamic compensation for nonlinearity and dispersion, and obtaining an intermediate pulse with a stable spectral width and phase distribution. The coupling processing module is configured to input the intermediate pulse into the output coupler at the end of the waveguide; the tapered waveguide end is connected to the output straight waveguide, and the low-loss UV-cured polymer generates morphological locking of the pulse shape at the dispersion cutoff point of the tapered waveguide and the interface of the straight waveguide; at the same time, it cures the pulse time-domain envelope shape determined by the dispersion cutoff effect. After being processed by the coupler, the output is a femtosecond pulse that retains its self-similar characteristics and has a stable shape and spectrum.

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