An on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte

Abstract

An on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte belongs to the field of functional photonic chip technology. It consists of a substrate layer, a lower cladding layer, a lower metal layer, a polymer grooved layer, an ion-polymer electrolyte core layer, and an upper metal layer, and the device is a MIM structure. The ion-polymer electrolyte core layer has an inverted ridge waveguide structure. The polymer electrolyte material PIL / PBI exhibits a photoimpedance effect; that is, when the detected optical signal propagates in the inverted ridge waveguide, it interacts with the polymer electrolyte, converting light energy into heat energy, increasing the concentration and activity of free ions inside the PIL / PBI, thereby changing its impedance value. This invention solves the problems of single detection dimension and insufficient responsivity in existing on-chip visible light detectors, realizing the detection of three dimensions of optical signal: polarization state, wavelength, and power. It has advantages such as fast response speed, simple fabrication process, low cost, small size, and high integrability.

Description

Technical Field

[0001] This invention belongs to the field of functional photonic chip technology, specifically relating to an on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte. Technical Background

[0002] With the rapid development of optical communication technology, integrated photonic chips have become a core technology for data center interconnection, high-speed signal processing, and high-performance computing in the post-Moore's Law era due to their advantages such as large capacity, low power consumption, high speed, and resistance to electromagnetic interference. In integrated optoelectronic systems, on-chip optical signal detectors are key components for realizing optical signal detection and real-time monitoring. Their working principle is mainly based on photonic effects (such as photoconductivity and photovoltaic effects) or thermal effects (such as pyroelectric effects) generated by the interaction of light and matter, converting optical signals into electrical signals for output. They play a crucial role in chip performance feedback, system stability, and functional regulation monitoring. In particular, optical signal detectors in the visible light band occupy an important position in fields such as biosensing, spectral analysis, environmental monitoring, and quantum information processing. Currently, on-chip optical detectors are mainly fabricated using silicon-based semiconductors or III-V group semiconductor materials and planar optical waveguide technology to achieve efficient detection of optical signals. However, they face challenges such as complex processes, difficulty in high-density integration, low coupling efficiency, high crosstalk, limited functionality, low responsivity, and slow response speed in the visible light band. Therefore, designing an on-chip visible light signal detector that is highly compatible with existing optoelectronic integration platforms, has a simple fabrication process, enables low crosstalk and high-density integration, and possesses multifunctional detection potential has become a key problem urgently needing to be solved in this field. Polymer electrolytes exhibit photoimpedance effect, meaning that under the stimulation of visible light signals, they absorb light energy and convert it into heat energy, increasing the concentration of free ions inside and thus changing the impedance of the material. This characteristic provides a novel approach for developing new optical signal detection mechanisms. Summary of the Invention

[0003] To address the limitations of existing on-chip photodetectors in the visible light band, such as limited detection dimensions and insufficient responsivity, this invention proposes an on-chip visible light signal detector based on the photoimpedance effect of a polymer electrolyte. During device operation, based on the photoimpedance effect of the ionic polymer electrolyte and combined with the designed waveguide structure, light signals of different wavelengths, powers, and polarization states can cause differential changes in the free ion concentration in the waveguide core material, leading to a regular change in the device impedance. By monitoring the impedance response curve, multi-dimensional information of the light signal can be acquired, exhibiting significant advantages such as multifunctionality, high sensitivity, and compact structure. Furthermore, the detector utilizes an ionic polymer electrolyte material, resulting in a simple fabrication process, low cost, small size, and high integrability, demonstrating excellent manufacturability and application potential. This device can be widely applied to applications requiring simultaneous differentiation of wavelength, power, and polarization, such as wavelength division multiplexing system monitoring, polarization state detection, portable spectrometers, laser power feedback control, and optofluidic sensing. It is particularly suitable for optical signal processing and micro / nano waveguide integrated systems, providing a feasible solution for constructing an advanced on-chip optoelectronic integrated photonics platform.

[0004] The present invention discloses an on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte, as shown in the attached figure. Figure 1 As shown, the device is a metal-dielectric-metal (MIM) waveguide structure, consisting of a substrate layer 1, a lower cladding layer 2, a lower metal layer 3, a polymer grooved layer 4, an ion-polymer electrolyte core layer 5, and an upper metal layer 6 from bottom to top. The polymer grooved layer 4 is divided into left and right parts by grooves. The ion-polymer electrolyte core layer 5 is an inverted ridge waveguide structure, consisting of a flat plate layer and a ridge layer. The ridge layer is embedded in the grooves of the polymer grooved layer 4 facing the substrate layer 1. The upper metal layer 6 is located on the flat plate layer of the ion-polymer electrolyte core layer 5. Light is transmitted along the ridge layer. The direction of light transmission is the length direction of the visible light signal detector, and the direction perpendicular to the light transmission is the width direction of the visible light signal detector. The lengths of the substrate layer 1, lower cladding layer 2, and lower metal layer 3 are equal to the lengths of the polymer grooved layer 4, the ion-polymer electrolyte core layer 5, and the upper metal layer 6. The widths of the substrate layer 1, lower cladding layer 2, and lower metal layer 3 are greater than the widths of the polymer grooved layer 4, the ion-polymer electrolyte core layer 5, and the upper metal layer 6. The entire device has a left-right symmetrical structure about the grooves of the polymer grooved layer 4.

[0005] Appendix Figure 1 The cross-section of the device at point a is shown in the attached figure. Figure 2As shown in (a), the thickness H1 of substrate 1 is 0.1 mm to 1 mm, and the thickness H2 of lower cladding 2 is 2 μm to 20 μm. The lower metal layer 3 on lower cladding 2 and the upper metal layer 6 on the ion-polymer electrolyte core layer 5 are obtained by vacuum evaporation, and their thickness H3 is the same, ranging from 20 nm to 200 nm. The polymer groove layer 4 is prepared by spin coating and photopolymerization. The ion-polymer electrolyte core layer 5 is obtained by photolithography, wet grooving, and filling with ion-polymer electrolyte on polymer groove layer 4, and its refractive index is greater than that of polymer groove layer 4. The width W3 of the ridge layer is 1 μm to 20 μm, and the thickness of the ridge layer is... The thickness H4 of the polymer groove layer 4 is the same as that of the upper metal layer 6, ranging from 1 μm to 20 μm. The width W2 of the polymer groove layer 4 on both sides of the groove is the same, ranging from 500 μm to 2 mm. The width W1 of the substrate layer 1, lower cladding layer 2, and lower metal layer 3 protruding from both ends of the polymer groove layer 4 is the same, ranging from 200 μm to 2000 μm. The thickness H5 of the plate layer of the ion polymer electrolyte core layer 5 is 0.5 μm to 5 μm, and the width W4 is the same as that of the upper metal layer 6, ranging from 1001 μm to 20020 μm, and W4 = 2 × W2 + W3. The width of the substrate layer 1, lower cladding layer 2, and lower metal layer 3 is the same, which is W4 + 2 × W1. Figure 1 A top view of the device is attached. Figure 2 As shown in (a), the length L of the device is 100μm~5000μm; the upper metal layer 6 forms the upper electrode region 7 with a width of W4; the lower metal layer 3 protruding from both ends of the polymer groove layer 4 forms the lower electrode region 8 with a width of W1.

[0006] The substrate layer 1 described in this invention is made of any one of silicon, gallium arsenide, and indium phosphide;

[0007] The material of the lower cladding layer 2 described in this invention is any one of silicon dioxide, PMMA, and SU-8;

[0008] The lower metal layer 3 and the upper metal layer 6 of the present invention are alloys composed of one or more of silver, aluminum, and gold, which have low absorption in the visible light band and good conductivity.

[0009] The polymer groove layer 4 of the present invention is any one of a series of transparent ultraviolet direct-write photoresist materials, including fluorinated bisphenol A phenolic resin (F-SU8), SU8 and Epo;

[0010] The ionic polymer electrolyte core layer 5 of this invention is a PIL / PBI composite electrolyte material. It is prepared by dissolving ionic liquid 1-allyl-3-vinylimidazolium chloride, N,N'-methylenebisacrylamide, and 2,2-azobis(ethylenebutyronitrile) in a polybenzimidazole (PBI) solution (the mass ratio of polybenzimidazole PBI powder to N,N-dimethylacetamide solvent in the PBI solution is 1:19) at a mass ratio of 4:1:0.2, with the mass ratio of ionic liquid 1-allyl-3-vinylimidazolium chloride and N,N'-methylenebisacrylamide to polybenzimidazole PBI powder being 2:3 to 3:2. The mixture is then thermosetting (90°C / 12h, 120°C / 12h) to obtain the PIL / PBI composite electrolyte material. For specific preparation methods and experimental spectra, please refer to the reference (Y. Song et al., All-Optical Controlling Waveguide Grating Filter Using Ionic-Gel Polymer Electrolyte Based on...). Photothermal Effect. IEEE ElectronDevice Letters, vol. 46(7), 2025, 1195-1198, doi: 10.1109 / LED.2025.3571060.). First, as attached Figure 3 As shown, this material exhibits a defined refractive index and absorptivity curve in the visible light band, with a refractive index higher than that of the polymer grooved layer 4, thus ensuring the transmission of probe light within the ion-polymer electrolyte core layer 5. Secondly, the material shows varying absorption for different wavelengths of light, possessing a certain photothermal effect, which can convert absorbed light energy into heat energy. Finally, the material is composed of a positively charged polymer cross-linked network and negatively charged free Cl⁻ ions, exhibiting ionic conductivity. Its conductivity is closely related to the concentration of free Cl⁻ ions, which increases with increasing temperature, as shown in the attached figure. Figure 4 As shown, the conductivity of the composite electrolyte material PIL / PBI increases with increasing temperature.

[0011] As attached Figure 5 The diagram shown illustrates the working principle of an on-chip visible light signal detector based on the photoresistivity effect of a polymer electrolyte, as described in this invention. (See attached diagram.) Figure 5 As shown in (a), when the device is working, the two probes of the impedance analyzer are brought into contact with the upper electrode region 7 and the lower electrode region 8, respectively, to form a measurement loop. The equivalent circuit is shown in the attached figure. Figure 5 As shown in (b). This on-chip photodetector can be equivalent to a variable resistor R1 and a variable capacitor C1 connected in parallel, which are sensitive to the polarization P, wavelength λ, and power O of light. The impedance Z measured by the impedance analyzer is expressed as:

[0012] (1)

[0013] Where R2 is the resistance of the wire and contact, R1(P, λ, O) is the bulk resistance of the ion polymer electrolyte core layer 5 electrolyte material PIL / PBI, which reflects the ease of ion migration and the concentration of free ions; C1(P, λ, O) is the capacitance determined by the dielectric properties of the ion polymer electrolyte core layer 5 electrolyte material PIL / PBI itself.

[0014] As attached Figure 5 As shown in (c), when the detected signal light (polarization P includes TE and TM modes, wavelength λ ranges from 300 to 700 nm, and power O ranges from 0 to 50 mW) is input into the ion polymer electrolyte core layer 5 with an inverted ridge waveguide structure for transmission, according to formulas (2) and (3), the electrolyte material PIL / PBI of the ion polymer electrolyte core layer 5 absorbs the light, and then the light energy is converted into heat energy, causing the temperature of the corresponding area in the ion polymer electrolyte core layer 5 to rise. .

[0015] (2)

[0016] (3)

[0017] Where Q is the heat generated by the absorbed light, φ is the light absorption coefficient, φ is the absorption area, φ is the power of the detected light, φ is the angular frequency of the detected light, φ is the speed of the detected light, φ1 and φ2 are the relative permittivity of the ion-polymer electrolyte core layer 5 electrolyte material PIL / PBI and the polymer grooved layer 4 material, respectively, d is the distance from the center of the photothermal region, φ is the volume of the ion-polymer electrolyte core layer 5 electrolyte material PIL / PBI in the region irradiated by the detected light, and φ is the thermal conductivity of the polymer.

[0018] Because light of different polarizations, wavelengths, and powers transmits different optical fields, and because the electrolyte material PIL / PBI absorbs light of different wavelengths (as shown in the attached figure), Figure 3The differences between photothermal conversion and photoelectric conversion result in varying temperature rise regions and degrees within the core layer 5, leading to corresponding changes in the activity and concentration of the free ions Cl⁻ generated by ionization, and consequently, changes in impedance Z. In this process, R1(P, λ, O) and C1(P, λ, O) in formula (1) are determined by the polarization P, wavelength λ, and power O of the detected light. Therefore, based on the photoimpedance effect of the electrolyte material PIL / PBI, this on-chip detector can convert light signals with specific polarization, wavelength, and power into corresponding electrical signals. By measuring the impedance curve, relevant information about the detected light signal can be obtained, thus achieving multifunctional, ultra-compact, and highly sensitive light detection.

[0019] Compared with existing device structures and fabrication techniques, the advantages of this invention are:

[0020] I. This invention is based on the electroimpedance effect of ion-polymer electrolytes and employs a metal-dielectric-metal (MIM) waveguide structure. On one hand, this structure is electrically equivalent to a circuit unit with a capacitor and a resistor in parallel, enabling direct impedance matching and efficient integration with back-end electronic circuits, greatly simplifying the signal processing flow. On the other hand, it constructs an efficient optical transmission channel, enhancing the interaction between light and materials and effectively suppressing optical losses caused by mode mismatch or radiation leakage. Through the synergistic effect of "enhanced response" and "reduced loss," this invention achieves efficient and low-noise conversion of optical signals to electrical signals, significantly improving detection sensitivity. Based on the above architecture, this invention maintains high detection performance while possessing an ultra-compact structural size, providing a feasible solution for the realization of monolithic optoelectronic integrated circuits.

[0021] II. Compared with existing on-chip photodetectors that rely on complex processes such as dry etching, heterojunction epitaxial growth, and ion implantation, the fabrication process of this invention is simple, avoiding high-cost and highly complex process steps. It has advantages such as small size, low cost, and easy integration, significantly improving the manufacturability and application potential of the device. It is suitable for applications that require simultaneous differentiation of light wavelength, power, and polarization, such as wavelength division multiplexing system monitoring, polarization state detection, portable spectrometers, laser power feedback control, and optofluidic sensing.

[0022] Thirdly, addressing the limitations of existing on-chip photodetectors, which suffer from functional homogenization and single detection dimensions due to material and structural constraints, this invention utilizes the intrinsic absorption differences of ionomer electrolyte materials for different wavelengths and the extreme sensitivity of the inverted ridge waveguide structure to the polarization state of the light field. Without introducing additional optical components, it achieves simultaneous detection of three core information dimensions of optical signals—wavelength, polarization, and power—on a single chip. This multi-dimensional sensing capability provides a new technical path and functional expansion space for high-density optical integration and optical computing systems. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the three-dimensional structure of an on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte according to the present invention.

[0024] Figure 2 (a) is Figure 1 A schematic diagram of the cross-section at position a; Figure 2 (b) is Figure 1 Top view of the component;

[0025] Figure 3 The refractive index curves and absorption curves of the ion polymer electrolyte core layer 5 material PIL / PBI described in this invention are shown in the 300nm~700nm wavelength range.

[0026] Figure 4 The curve showing the relationship between the conductivity of the PIL / PBI material in the ion-polymer electrolyte core layer 5 of this invention and temperature.

[0027] Figure 5 This is a schematic diagram illustrating the working principle of the on-chip visible light signal detector described in this invention; wherein, Figure 5 (a) in the diagram is a schematic diagram of the detection process; Figure 5 (b) in the diagram is the equivalent circuit diagram for the probe; Figure 5 (c) is a schematic diagram of the photoimpedance effect of the PIL / PBI material in the ion polymer electrolyte core layer 5.

[0028] Figure 6 This is a simulation diagram of the waveguide cross-section optical field distribution at position a of device in Embodiment 1 of the present invention;

[0029] Figure 7 This is a flowchart illustrating the fabrication process of the device in Embodiment 1 of the present invention;

[0030] Figure 8 The image shows the characterization pattern of the device prepared in Example 1 of this invention; wherein Figure 8 (a) is an atomic force microscope image of the lower metal layer 3 gold film prepared by vapor deposition process; Figure 8 (b) is an optical microscope image of the polymer grooved layer 4 after grooving; Figure 8 (c) is a scanning electron microscope image of the upper surface of the ion polymer electrolyte core layer 5.

[0031] Figure 9 This is a set of graphs showing the optical signal detection curves of the device prepared in Example 1 of the present invention for different polarization states (TE / TM), wavelengths (405nm / 532nm / 605nm), and optical powers (0-50mW).

[0032] Figure 10 These are two sets of response characteristic curves of the photodetector prepared in Example 1 of the present invention; wherein, Figure 10 (a) in the figure is the dynamic response time curve of the device with polarization TE, wavelength 405nm and optical power varying between 20mW and 30mW; Figure 10 (b) in the figure is the dynamic response time curve of the device with polarization TM, wavelength 532nm, and optical power varying between 30mW and 40mW.

[0033] like Figure 1 The diagram shows a three-dimensional structure of an on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte. The components are named as follows: substrate layer 1, lower cladding layer 2, lower metal layer 3, polymer groove layer 4, ion polymer electrolyte core layer 5, and upper metal layer 6.

[0034] like Figure 2 As shown, (a) is Figure 1 A cross-sectional view at position a is shown, with the components named as follows: substrate layer 1, lower cladding layer 2, lower metal layer 3, polymer groove layer 4, ion-polymer electrolyte core layer 5, and upper metal layer 6; (b) is... Figure 1 The top view of the device shows the regions as follows: Upper electrode region 7, Lower electrode region 8.

[0035] like Figure 3 The figure shows the refractive index and absorption curves of PIL / PBI in the 300nm~700nm wavelength range. The refractive index data were obtained by ellipsometer measurement, and the absorption spectrum was measured using a UV-3600 spectrophotometer. The test results show that PIL / PBI materials exhibit high refractive index values ​​in this wavelength range, and the refractive index and absorption coefficient show significant wavelength dependence with wavelength.

[0036] like Figure 4 As shown in the figure, the conductivity of PIL / PBI is related to temperature. It can be seen that as the temperature increases, the concentration of free ions in the PIL / PBI film increases, and its conductivity increases.

[0037] like Figure 5As shown, (a) is a schematic diagram of the on-chip visible light signal detector. The detected light with polarization state P, wavelength λ, and optical power O is input into the inverted ridge waveguide for transmission. The two pins of the impedance analyzer are connected to the upper electrode region 7 and the lower electrode region 8, respectively; (b) is the equivalent circuit diagram of the detection in (a). The on-chip detector is equivalent to a circuit unit consisting of a variable capacitor C1 and a variable resistor R1 connected in parallel, which are sensitive to the polarization, wavelength, and power of the light. The wire and contact resistance R2 are equivalent to a fixed resistance. The information of the detected light can be determined by measuring the impedance curve through the impedance analyzer; (c) The figure shows the photoresistivity effect of the polymer electrolyte when the probed light interacts with the PIL / PBI. When the probed light is not transmitted, there are free ions with a certain concentration and activity in the ion polymer electrolyte core layer 5. When the probed light signal is transmitted in the waveguide, it interacts with the ion polymer electrolyte core layer 5. According to formulas (2) and (3), the light energy is converted into heat energy. The probed light causes the inverted ridge PIL / PBI waveguide to generate heat, which increases the concentration and activity of free ions inside the PIL / PBI, thereby reducing its impedance value and realizing the conversion of light signal into electrical signal.

[0038] like Figure 6 The figure shows a simulation diagram of the optical field distribution of the waveguide cross section at device a. The simulation was performed using COMSOL Multiphysics software. During the simulation, we selected the material and waveguide size used in Example 1. It can be clearly seen from the simulation diagram that the optical field is mainly concentrated in the inverted ridge waveguide and the optical field is well confined, which is conducive to the full interaction between the probe light and the PIL / PBI material to achieve efficient detection.

[0039] like Figure 7 The diagram shows the fabrication process flow of an on-chip visible light signal detector. In the diagram, 1 is a silicon substrate, 2 is a silicon dioxide lower cladding layer, 3 is a metal film under metal layer prepared by vacuum evaporation, 4' is a photoresist film prepared by spin coating and photocuring, 7 is a mask for photolithography to prepare waveguide grooves, 4 is a polymer groove layer obtained by wet etching, 5 is an ion polymer electrolyte core layer, and 6 is a metal film on metal layer prepared by vacuum evaporation.

[0040] like Figure 8As shown, (a) is an atomic force microscope image of the gold film of metal layer 3 prepared by vapor deposition; (b) is an optical microscope image of the polymer grooved layer 4 after grooving; and (c) is a scanning electron microscope image of the upper surface of the ion polymer electrolyte core layer 5. In the actual fabrication process, we actually fabricated the device using the materials and waveguide dimensions selected in Example 1. As shown in Figure (a), the average surface roughness of the gold film prepared by vapor deposition is 0.36 nm; as shown in Figure (b), the polymer grooved layer obtained by spin coating, photopolymerization and wet etching processes has a good morphology and the size is consistent with the design in Example 1; as shown in Figure (c), the PIL / PBI material has good film-forming properties and small fluctuations.

[0041] like Figure 9 The figure shows the optical signal detection curves of the on-chip visible light signal detector under different polarizations (TE / TM), different wavelengths (405nm / 532nm / 605nm), and different optical powers (0-50mW). We actually fabricated the device using the materials and waveguide dimensions selected in Example 1. As can be seen from the figure, in terms of optical power, the impedance value of the device exhibits a phased change with the increase of input optical power, generally divided into three typical operating ranges: in the lower power range, the impedance value decreases slowly, showing a gradual decrease region (corresponding to...). Figure 9 (White background); then enters the linear descent region (light gray background), where impedance shows an approximately linear relationship with increasing power; when the power further increases to a higher level, the impedance change tends to saturate, entering the saturation region (dark gray background). Secondly, in the polarization dimension, for the same wavelength of probed light, the impedance responses corresponding to the TE and TM polarization states differ significantly. Taking the linear descent region as an example, the response range corresponding to the TM polarization state is wider than that of the TE polarization state; simultaneously, under the same optical power conditions, the impedance value corresponding to the TM polarization state is always lower than that of the TE polarization state. In the wavelength dimension, for probed light with the same polarization state and the same optical power, the impedance values ​​corresponding to different wavelengths show a regular difference. Specifically, the impedance value corresponding to the 405nm wavelength is the smallest, followed by 532nm, and the largest is 605nm; furthermore, the distribution range of the three working intervals corresponding to different wavelengths also shows significant differences.

[0042] like Figure 10As shown, (a) Figure shows the dynamic response time curve of the on-chip visible light detector when the polarization TE, wavelength 405nm, and optical power change between 20mW and 30mW. We actually fabricated the device using the materials and waveguide dimensions selected in Example 1. It can be seen that the rise time of the device is 0.09s and the fall time is 0.24s; (b) Figure shows the dynamic response time curve of the on-chip visible light detector when the polarization TM, wavelength 532nm, and optical power change between 30mW and 40mW. It can be seen that the rise time of the device is 0.23s and the fall time is 0.81s. Detailed Implementation

[0043] The present invention will now be described more clearly and completely with reference to the accompanying drawings. It should be noted that those skilled in the art will gain a deeper understanding of the advantages and functions of the present invention from this description. However, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] In this embodiment, the substrate layer 1 selected for the device is a silicon substrate with a thickness of H1=0.5mm.

[0046] In this embodiment, the lower cladding layer 2 of the device is silicon dioxide with a thickness of H2=5μm.

[0047] In this embodiment, the lower metal layer 3 and the upper metal layer 6 are gold films with a thickness of H3=30nm; the ion polymer electrolyte core layer 5 uses PIL / PBI electrolyte material, with a ridge width W3=2μm, a ridge height H4=2μm, a plate thickness H5=1μm, and a width W4=1002μm; the polymer groove layers 4 on both sides of the ridge of the ion polymer electrolyte core layer 5 are F-SU8 with a width W2=1mm and a thickness H4=2μm; the substrate layer 1, the lower cladding layer 2, and the lower metal layer 3 protruding from both ends of the polymer groove layer 4 have a width W1=1000μm; the length of the device L=3000μm; the upper electrode region 7 has a width W4=1002μm; and the lower electrode region 8 has a width W1=1000μm.

[0048] In this embodiment, the device size parameters proposed in this invention are simulated using COMSOL Multiphysics software to obtain an example diagram of the cross-sectional optical field distribution of the device's optical transmission, as shown in the attached figure. Figure 6 As shown in the figure. Simulation results show that the optical field energy of the probed light is mainly concentrated in the ion polymer electrolyte core layer 5, which enables the probed light to fully interact with the PIL / PBI material, thereby achieving efficient detection.

[0049] The fabrication steps of the on-chip visible light signal detector based on the photoresistivity effect of polymer electrolyte in this embodiment are as follows: Figure 7 As shown, the specific description is as follows:

[0050] (a) Cleaning Si substrate 1 and silicon dioxide cladding 2: First, ultrasonic cleaning of Si substrate 1 and silicon dioxide cladding 2 was performed for 30 min using acetone solution; then, the surface of silicon dioxide cladding 2 was wiped three times in one direction using acetone-soaked cotton balls; then, the above wiping process was repeated with ethanol-soaked cotton balls to remove acetone residue; then, after rinsing with deionized water multiple times, nitrogen purging technology was used to achieve surface dehydration; finally, the cleaned Si substrate 1 was transferred to a constant temperature oven for drying (temperature 120℃, time 30 min); after natural cooling to room temperature, plasma surface treatment was performed for 60 s;

[0051] (b) Deposition of the lower metal layer 3 gold film: A gold film with a thickness of 30 nm is deposited on the silicon dioxide lower cladding layer 2 by vacuum evaporation process, followed by plasma surface treatment for 30 s;

[0052] (c) Spin-coating and photolithography of polymer groove layer 4: The polymer groove layer 4 material F-SU8 is spin-coated onto the prepared lower metal layer 3 using a spin-coating process with a speed of 3000 r / min and a time of 30 s. Then, it is pre-baked at a temperature / time of 65℃ / 5 min, 95℃ / 10 min, and 120℃ / 5 min to evaporate the organic solvent. Then, it is allowed to cool naturally to room temperature to obtain an F-SU8 polymer film 4' with a thickness of about 2 μm. Then, the designed waveguide groove structure photolithography mask 7 (with the same structure as the groove structure) is covered on the negative F-SU8 polymer film 4' and is in close contact with its surface. The non-waveguide groove area is exposed to ultraviolet light with a wavelength of 350~400 nm for 200 s using an ultraviolet lithography machine. After exposure, it is baked at a temperature / time of 120℃ / 10 min and then allowed to cool naturally to room temperature.

[0053] (d) Development of polymer groove layer 4: The exposed F-SU8 film was immersed and developed using PGMEA developer to remove unexposed areas and form a clearly patterned groove structure; then, isopropanol solution was used to clean and remove residual developer, followed by rinsing with deionized water to replace the isopropanol, and finally the sample surface was dried with nitrogen; the cleaned sample was placed on a hot plate and baked at 120°C for 10 min for hardening treatment, and then naturally cooled to room temperature, thus completing the patterning preparation of the polymer groove layer 4 structure; finally, a sealing film was attached to the lower electrode 8 area of ​​the lower metal layer 3 to protect the area;

[0054] (e) Spin-coating filled ionic polymer electrolyte core layer 5: The ionic liquid 1-allyl-3-vinylimidazolium chloride, N,N'-methylenebisacrylamide and 2,2-azobis(ethylenebutyronitrile) (mass ratio of 4:1:0.2) dissolved in polybenzimidazole PBI solution (mass ratio of ionic liquid 1-allyl-3-vinylimidazolium chloride and N,N'-methylenebisacrylamide to polybenzimidazole PBI solution is 1:1, rotation speed 2500 r / min, time: 20 s) is spin-coated onto the surface of the treated device. Immediately after spin-coating, the device is placed in an oven for heat curing at 90°C / 12h and 120°C / 12h to allow the solvent to evaporate. Then, it is naturally cooled to room temperature to obtain a ridged electrolyte material coating. The height of the ridge layer in the tank is consistent with the depth of the tank, which is about 2 μm. The thickness of the flat layer is about 1 μm.

[0055] (f) Deposition of the metal layer 6 (gold film): A 30 nm thick gold film is deposited on the ion-polymer electrolyte core layer 5 using a vacuum evaporation process, and then the sealing film is removed. This process produces the on-chip visible light signal detector based on the ion-polymer electrolyte described in this invention, meeting the required specifications.

[0056] In this embodiment, blade cutting was used for cleaving, and the performance of the fabricated device was characterized using an optical transmission testing system. The polarization state of the probed optical signal was selected as either transverse electric mode (TE) or transverse magnetic mode (TM), with wavelengths of 405 nm, 532 nm, and 605 nm, respectively. The optical power range was set to 0–50 mW. The input signal terminal of the device fabricated in this embodiment (…) Figure 1 (As indicated by the middle arrow) Input the probed light with different parameter combinations, and the results are shown in the appendix. Figure 9As shown, the impedance response characteristics under different optical signal conditions were obtained through testing. First, in terms of optical power, the impedance value of the device exhibits a phased change with the increase of input optical power, which can be divided into three typical operating ranges: in the lower power range, the impedance value decreases slowly, showing a gradual decrease region (corresponding to the white background in the attached figure); then it enters the linear decrease region (light gray background), where the impedance has an approximately linear relationship with the increase of power; when the power is further increased to a higher level, the impedance change tends to saturate, entering the saturation region (dark gray background), demonstrating the nonlinear response mechanism of the device under different light intensity conditions, providing a clear mapping relationship for power detection. Second, in terms of polarization, for the same wavelength of detected light, there are significant differences in the impedance responses corresponding to the TE and TM polarization states. Taking the linear decrease region as an example, the response range corresponding to the TM polarization state is wider than that of the TE polarization state; at the same optical power condition, the impedance value corresponding to the TM polarization state is always lower than that of the TE polarization state, indicating that the device has a high sensitivity to the polarization state of the incident light and can achieve polarization state discrimination without the aid of external optical components. In terms of wavelength, for probed light with the same polarization state and optical power, the impedance values ​​corresponding to different wavelengths exhibit a regular difference. Specifically, the impedance value is lowest at 405nm, followed by 532nm, and highest at 605nm. Furthermore, the distribution ranges of the three working intervals corresponding to different wavelengths also show significant differences, further verifying the device's wavelength resolution capability. This verifies that the photodetector proposed in this invention can simultaneously detect the three core information dimensions of optical signals—polarization state, wavelength, and power—on a single chip, demonstrating excellent multi-parameter detection capabilities.

[0057] In this embodiment, two sets of modulated optical signals with different polarization states, wavelengths, and power combinations were used to test the dynamic response characteristics of the fabricated photodetector. Specific test conditions were set as follows: one set used TE polarization, a 405nm wavelength, and optical power alternated between 20mW and 30mW; the other set used TM polarization, a 532nm wavelength, and optical power alternated between 30mW and 40mW. The time response curves were obtained by real-time acquisition of the device output response, as shown below. Figure 10 (a) and Figure 10 As shown in (b). Test results demonstrate that the photodetector proposed in this invention exhibits excellent dynamic response performance in various signal modes. Figure 10 As shown in (a), under TE polarization, 405nm wavelength, and alternating 20mW and 30mW signal light excitation, the device's rise time (defined as the time required for the response value to rise from 10% to 90%) is 0.09s, and its fall time (the time required for the response value to fall from 90% to 10%) is 0.24s. Figure 10As shown in (b), under TM polarization, 532nm wavelength, and alternating signal light excitation of 30mW and 40mW, the rise time of the device is 0.23s and the fall time is 0.81s. Both sets of test results indicate that the response time of the device is at the sub-second level, enabling it to quickly track changes in the power of the input optical signal. In summary, the photodetector fabricated in this invention possesses sensitive response capabilities, and its response speed is significantly superior to that of photodetectors with traditional structures. Combined with its compact structure and simple fabrication process, this invention demonstrates promising practical prospects and technological advantages in applications requiring high response speeds, such as high-speed optical communication, real-time optical signal processing, and optical computing.

Claims

1. An on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte, characterized in that: The device is a metal-dielectric-metal waveguide structure, consisting of a substrate layer (1), a lower cladding layer (2), a lower metal layer (3), a polymer grooved layer (4), an ion-polymer electrolyte core layer (5), and an upper metal layer (6) from bottom to top. The polymer grooved layer (4) is divided into left and right parts by grooves. The ion-polymer electrolyte core layer (5) is an inverted ridge waveguide structure, consisting of a flat plate layer and a ridge layer. The ridge layer is embedded in the groove of the polymer grooved layer (4) facing the substrate layer (1). The upper metal layer (6) is located on the flat plate layer of the ion-polymer electrolyte core layer (5). Light is transmitted along the ridge layer and along the light... The transmission direction of light is the length direction of the visible light signal detector, and the transmission direction of light perpendicular to the width direction of the visible light signal detector. The lengths of the substrate layer (1), the lower cladding layer (2), and the lower metal layer (3) are equal to the lengths of the polymer groove layer (4), the ion polymer electrolyte core layer (5), and the upper metal layer (6). The widths of the substrate layer (1), the lower cladding layer (2), and the lower metal layer (3) are greater than the widths of the polymer groove layer (4), the ion polymer electrolyte core layer (5), and the upper metal layer (6). The entire device is a left-right symmetrical structure about the light transmission direction in the polymer groove layer (4).

2. The on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte as described in claim 1, characterized in that: The thickness H1 of the substrate layer (1) is 0.1 mm to 1 mm, and the thickness H2 of the lower cladding layer (2) is 2 μm to 20 μm; the thickness H3 of the lower metal layer (3) and the upper metal layer (6) is the same, 20 nm to 200 nm; the refractive index of the ion polymer electrolyte core layer (5) is greater than that of the polymer groove layer (4), the width W3 of the ridge layer is 1 μm to 20 μm, the thickness of the ridge layer is the same as the thickness H4 of the polymer groove layer (4), 1 μm to 20 μm, and the width W2 of the polymer groove layer (4) on both sides of the groove is the same, 500 μm to 2 mm; the substrate layer (1), the lower cladding layer (2), and the lower metal layer (6) protrude from both ends of the polymer groove layer (4). 3) The width W1 is the same as 200μm~2000μm; the thickness H5 of the plate layer of the ion polymer electrolyte core layer (5) is 0.5μm~5μm, and the width is the same as the width W4 of the upper metal layer (6) is 1001μm~20020μm, and W4=2×W2+W3; the width of the substrate layer (1), the lower cladding layer (2) and the lower metal layer (3) is the same, which is W4+2×W1; the upper metal layer (6) constitutes the upper electrode region (7) with a width of W4; the lower metal layer (3) protruding at both ends of the polymer groove layer (4) constitutes the lower electrode region (8) with a width of W1; the length L of the visible light signal detector is 100μm~5000μm.

3. The on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte as described in claim 1, characterized in that: The substrate (1) is made of any one of silicon, gallium arsenide, and indium phosphide; the lower cladding layer (2) is made of any one of silicon dioxide, PMMA, and SU-8; the lower metal layer (3) and the upper metal layer (6) are alloys composed of one or more of silver, aluminum, and gold, which have low absorption in the visible light band and good conductivity; the polymer groove layer (4) is made of any one of a series of transparent ultraviolet direct-write photoresist materials, including fluorinated bisphenol A phenolic resin (F-SU8), SU8, and Epo; and the ion polymer electrolyte core layer (5) is made of PIL / PBI composite electrolyte material.

4. The on-chip visible light signal detector based on the photoimpedance effect of polymer electrolyte as described in claim 1, characterized in that: The polarization P of the signal light input to the ridge layer of the ion polymer electrolyte core (5) includes TE and TM modes, with a wavelength λ ranging from 300 to 700 nm and a power O ranging from 0 to 50 mW.

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