Thin film lead zirconate titanate-based high-resolution broadband integrated spectrometer and preparation method thereof
By connecting a staggered resonant wavelength microring resonator based on thin-film lead zirconate titanate in series with an arrayed waveguide grating, and combining the ferroelectric properties of lead zirconate titanate thin film with the segmented polarization method, the problem of balancing high resolution and wide bandwidth in traditional integrated spectrometers is solved, realizing high-resolution, wide-bandwidth and low-power spectral measurement, which is suitable for optical coherence tomography, biosensing imaging and optical communication.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-07
AI Technical Summary
Traditional integrated spectrometers struggle to achieve a good balance between high resolution and wide spectral bandwidth. Furthermore, existing two-stage series structures suffer from high power consumption, slow response, and poor stability. In particular, thermally tuned spectrometers require continuous power supply, which affects device consistency and measurement accuracy.
A high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate is adopted. By configuring staggered microring resonators in series with arrayed waveguide gratings, the ferroelectric properties and residual polarization effect of lead zirconate titanate thin films are utilized to achieve precise alignment of the resonant wavelength with the arrayed waveguide grating channels. Wavelength tuning is performed by combining segmented polarization method to reduce power consumption and improve stability.
It achieves a doubling of spectral sampling density under the same bandwidth, and maintains stability without continuous power supply after non-volatile tuning, realizing an integrated spectral measurement system with high resolution, large bandwidth and low power consumption, suitable for optical coherence tomography, biosensing imaging and optical communication.
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Figure CN121804662A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of integrated optical technology, and more specifically, to a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate and its preparation method. Background Technology
[0002] Integrated optical spectrometers, due to their compact size, potential low-cost mass production advantages, and wide spectral bandwidth and high resolution capabilities, have wide applications in fields such as optical communication, chemical spectroscopy, biosensing, astronomy, and 3D imaging. However, traditional single-structure spectrometers generally face a core challenge: it is difficult to achieve a good balance between high resolution and wide spectral bandwidth. Improved resolution is often accompanied by limited bandwidth, and vice versa.
[0003] To overcome this limitation, a two-stage series structure was proposed. However, this structure generally suffers from high power consumption, slow response, and poor stability. In particular, the thermally tunable method requires continuous power supply to maintain resonance stability, which not only increases energy consumption but also easily introduces thermal noise and long-term drift. In addition, traditional tunable structures are extremely sensitive to nanometer-level deviations in waveguide dimensions and material thickness during manufacturing, making it difficult to precisely align the actual resonant wavelength of the microring resonator with the center of the arrayed waveguide grating channel, affecting the overall spectral measurement accuracy and device consistency.
[0004] Therefore, there is an urgent need for an integrated spectrometer structure that combines high resolution, wide bandwidth, low power consumption, and long-term stability to address the shortcomings of traditional solutions in terms of energy consumption and stability. Summary of the Invention
[0005] In view of this, this disclosure provides a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate and its preparation method.
[0006] One aspect of this disclosure provides a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate, comprising: a substrate; a silicon dioxide lower cladding layer disposed on the substrate; a lead zirconate titanate thin-film waveguide layer disposed on the silicon dioxide lower cladding layer, wherein the lead zirconate titanate thin-film waveguide layer contains a plurality of microring resonators and a plurality of arrayed waveguide gratings, each arrayed waveguide grating being connected to each microring resonator via a waveguide; a segmented periodic metal electrode arrangement system disposed in each straight waveguide region of the microring resonators; wherein the plurality of microring resonators are configured with staggered resonant wavelengths, the interval between adjacent resonant wavelengths being 1 / n of the channel spacing of the arrayed waveguide gratings, where n represents the number of microring resonators or arrayed waveguide gratings; the spectrometer is configured to be able to change the local waveguide refractive index by utilizing the residual polarization effect of the lead zirconate titanate thin film through a segmented polarization method, so as to achieve alignment of the resonant wavelength with the center of the arrayed waveguide grating channel.
[0007] According to embodiments of this disclosure, a plurality of microring resonators are configured as racetrack-shaped microring resonators; wherein each racetrack-shaped microring resonator includes two semi-circular curved waveguides, two straight waveguides, and a directional coupler.
[0008] According to embodiments of this disclosure, multiple microring resonators have different waveguide widths, forming staggered resonant wavelengths; wherein the interval between adjacent resonant wavelengths is 1 / n of the free spectral range of the microring resonator.
[0009] According to embodiments of this disclosure, the arrayed waveguide grating includes: an input channel waveguide for receiving a composite optical signal with a 1 / n wavelength interval having a free spectral range after incident light passes through a microring resonator; an input planar waveguide region for diffracting the composite optical signal; an arrayed waveguide region for generating a phase difference between optical signals of different wavelengths in the composite optical signal; an output planar waveguide region for diffracting the composite optical signal and focusing optical signals of different wavelengths; and an output channel waveguide for outputting an optical signal of a specific wavelength.
[0010] According to embodiments of this disclosure, the channel spacing between the output channel waveguides is equal to the free spectral range of the microring resonator, so that multiple wavelengths periodically transmitted by the microring resonator can be accurately separated by the arrayed waveguide grating.
[0011] According to embodiments of this disclosure, the arrayed waveguide region is connected to the input planar waveguide region and the output planar waveguide region by tapered waveguides.
[0012] According to embodiments of this disclosure, the array waveguide region is configured as a rectangular wiring configuration; wherein, the main portion of the array waveguide region uses a wide waveguide for optical transmission, and the curved portion of the array waveguide region uses a single-mode Euler curved waveguide for optical transmission.
[0013] According to an embodiment of this disclosure, a segmented periodic metal electrode arrangement system includes: a first metal electrode segment disposed in one section of a straight waveguide region of a microring resonator, wherein the width of the first metal electrode segment is less than a preset threshold for achieving fine-tuning of the wavelength; and a second metal electrode segment disposed in another section of a straight waveguide region of the microring resonator, wherein the width of the second metal electrode segment is greater than a preset threshold for achieving coarse-tuning of the wavelength.
[0014] According to embodiments of this disclosure, the tuning step of the first metal electrode segment is 0.01 nm to 0.04 nm, and the tuning step of the second metal electrode segment is 0.1 nm to 0.4 nm.
[0015] Another aspect of this disclosure provides a method for fabricating a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate, comprising: depositing a silicon dioxide lower cladding layer of a predetermined thickness on a silicon substrate; depositing a lead zirconate titanate thin film of a predetermined thickness on the silicon dioxide lower cladding layer using a sol-gel method; fabricating a microring resonator and an arrayed waveguide grating based on the lead zirconate titanate thin film using photolithography and inductively coupled plasma etching processes; depositing and patterning metal electrodes to obtain the desired metal electrode pattern by stripping; depositing silicon oxide of a predetermined thickness as an upper cladding layer; and, based on the upper cladding layer, realizing silicon oxide windowing using photolithography and inductively coupled plasma etching processes to expose the desired metal electrodes for applying voltage polarization.
[0016] Compared with the prior art, the high-resolution broadband integrated spectrometer and preparation method based on thin-film lead zirconate titanate provided in this disclosure have at least the following beneficial effects:
[0017] The high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate disclosed herein employs a monolithic integrated structure consisting of two microring resonators with staggered resonant wavelengths and two arrayed waveguide gratings connected in series. It utilizes the ferroelectric properties of thin-film lead zirconate titanate by setting multiple tiny metal electrodes in the straight waveguide region of the microring resonator. By using a segmented polarization method to change the local waveguide refractive index through the residual polarization effect of the ferroelectric thin-film lead zirconate titanate, it achieves precise alignment between the resonant wavelength and the center of the arrayed waveguide grating channel. After tuning and alignment, the accuracy of this spectrometer is 1 / n of the free spectral range of the microring resonator.
[0018] The high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate disclosed herein can double the spectral sampling density under the same bandwidth. After non-volatile tuning, it can maintain the stability of spectral measurement without continuous power supply, realizing an integrated spectral measurement system with high resolution, large bandwidth and low power consumption, which is suitable for applications such as optical coherence tomography, biosensing imaging and optical communication. Attached Figure Description
[0019] The above and other objects, features, and advantages of this disclosure will become clearer from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:
[0020] Figure 1 A schematic diagram illustrates the structure of a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate according to an embodiment of the present disclosure;
[0021] Figure 2 A schematic diagram of a microring resonator according to an embodiment of the present disclosure is shown.
[0022] Figure 3 The transmission spectrum diagrams of two microring resonators with staggered resonant wavelengths according to embodiments of the present disclosure are schematically shown.
[0023] Figure 4 A schematic diagram of an arrayed waveguide grating according to an embodiment of the present disclosure is shown.
[0024] Figure 5 The transmission spectrum of an arrayed waveguide grating according to an embodiment of the present disclosure is schematically shown.
[0025] Figure 6 The diagram illustrates a process flow chart of a method for fabricating a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate according to an embodiment of the present disclosure. Detailed Implementation
[0026] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.
[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.
[0029] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).
[0030] Integrated optical spectrometers, due to their compact size, potential low-cost mass production advantages, and wide spectral bandwidth and high resolution capabilities, have wide applications in optical communication, chemical spectroscopy, biosensing, astronomy, and 3D imaging. Especially in applications such as optical coherence tomography (OCT), achieving both high resolution and wide spectral bandwidth is crucial for improving system performance. Existing integrated spectrometers mainly include several types, such as Fourier transform spectrometers, which can achieve sub-nanometer resolution using interferograms formed by Mach-Zehnder interferometer arrays; and spectrometers based on dispersive elements, such as echo gratings, arrayed waveguide gratings (AWGs), angular multimode interferometers, and photonic crystals, which offer different solutions. However, traditional single-structure spectrometers generally face a core challenge: it is difficult to achieve a good balance between high resolution and wide spectral bandwidth; resolution improvement often comes with bandwidth limitation, and vice versa.
[0031] To overcome this limitation, a two-stage cascaded structure was proposed, aiming to balance high resolution and large bandwidth. Theoretically, a cascaded two-stage AWG spectrometer can improve bandwidth and resolution by expanding the Free Spectral Range (FSR) and increasing the number of channels. However, achieving high-resolution AWGs requires extremely stringent manufacturing precision (such as nanometer-level control of waveguide dimensions and optical path difference). Even minute process deviations can easily lead to increased channel crosstalk and insertion loss, severely restricting its actual performance and yield. A micro-ring resonator (MRR) cascaded AWG scheme utilizes the MRR's ultra-high spectral resolution (derived from its high Q value) and compact size as a pre-selection or post-processing unit for the AWG. This structure theoretically can achieve excellent performance. However, inherent errors in the manufacturing process (such as minor fluctuations in material thickness and waveguide dimensions) can cause the actual resonant wavelength of the MRR to drift from the design value, resulting in a severe mismatch with the preset channel center wavelength of the AWG. This mismatch forces the system to rely on complex real-time wavelength tuning mechanisms and additional data processing algorithms for compensation, which not only significantly increases system complexity and power consumption but also reduces long-term stability.
[0032] Lead zirconate titanate (PZT), also known as Pb(Zr, Ti)O3, is a novel functional material with excellent ferroelectric properties (high electro-optic coefficient and significant remanent polarization effect), offering a revolutionary approach to solving the aforementioned challenges. The most attractive feature of PZT films is their strong piezoelectric and electro-optic coefficients, making them an ideal choice for piezoelectric sensing and electro-optic modulators. Furthermore, as a polycrystalline ferroelectric material, its non-volatility is a significant advantage. For example, by applying an electric field to locally polarize the PZT film, stable flipping of its ferroelectric domains can be induced. After removing the electric field, the refractive index change caused by remanent polarization can be maintained almost permanently. Wavelength tuning based on this effect can be maintained without continuous power supply after calibration, completely eliminating the static power consumption problem caused by traditional tuning methods (such as thermal tuning).
[0033] Therefore, this disclosure aims to utilize the ferroelectric properties and non-volatile tuning capability of PZT thin films to construct a novel high-resolution broadband monolithic integrated spectrometer, thereby significantly reducing power consumption and simplifying the complexity of the on-chip system.
[0034] To make the objectives, technical solutions and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.
[0035] Figure 1 A schematic diagram of a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate according to an embodiment of the present disclosure is shown.
[0036] like Figure 1 As shown, the structure of the high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate in this embodiment may include, for example, a substrate, a silicon dioxide cladding layer, a lead zirconate titanate thin-film waveguide layer, and a segmented periodic metal electrode arrangement system.
[0037] The substrate can be, for example, a silicon substrate.
[0038] The silicon dioxide undercoat is disposed on the substrate, and its thickness can be, for example, 2-3 μm.
[0039] The lead zirconate titanate thin film waveguide layer is disposed on the silicon dioxide underlayer, and its thickness can be, for example, 300 nm.
[0040] In this embodiment of the disclosure, the lead zirconate titanate thin film waveguide layer is provided with a plurality of micro-ring resonators and a plurality of arrayed waveguide gratings, and each arrayed waveguide grating is connected to each micro-ring resonator through a waveguide.
[0041] For example, two microring resonators (MRR1 and MRR2) and two arrayed waveguide gratings (AWG1 and AWG2) can be disposed within the lead zirconate titanate thin film waveguide layer. The two microring resonators are configured with staggered resonant wavelengths, and the interval between adjacent resonant wavelengths is half the channel spacing of the arrayed waveguide gratings (if the number of microring resonators and arrayed waveguide gratings are both n, then the interval between adjacent resonant wavelengths is 1 / n of the channel spacing of the arrayed waveguide gratings). The free spectral range of a single microring resonator is equal to the channel spacing of the arrayed waveguide gratings.
[0042] The segmented periodic metal electrode arrangement system is located in each straight waveguide region of the microring resonator.
[0043] In this embodiment of the disclosure, the spectrometer is configured to change the local waveguide refractive index by using the residual polarization effect of the lead zirconate titanate film through segmented polarization, so as to achieve precise alignment of the resonant wavelength with the center of the arrayed waveguide grating channel.
[0044] The high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate disclosed herein employs a monolithic integrated structure consisting of two microring resonators with staggered resonant wavelengths and two arrayed waveguide gratings connected in series. It utilizes the ferroelectric properties of thin-film lead zirconate titanate by setting multiple tiny metal electrodes in the straight waveguide region of the microring resonator. By using a segmented polarization method to change the local waveguide refractive index through the residual polarization effect of the ferroelectric thin-film lead zirconate titanate, it achieves precise alignment between the resonant wavelength and the center of the arrayed waveguide grating channel. After tuning and alignment, the accuracy of this spectrometer is 1 / n of the free spectral range of the microring resonator.
[0045] According to embodiments of this disclosure, a plurality of microring resonators are configured as racetrack-shaped microring resonators, as shown in Figure 2.
[0046] Figure 2 A schematic diagram of a microring resonator according to an embodiment of the present disclosure is shown.
[0047] like Figure 2 As shown, the microring resonator in this embodiment is a racetrack-shaped microring resonator, and each racetrack-shaped microring resonator includes: two semi-circular curved waveguides, two straight waveguides, and a directional coupler.
[0048] In this embodiment, the center wavelength of the microring resonator can be selected as, for example, 1549.8 nm and 1550 nm, respectively, and the free spectral range can be, for example, 0.4 nm.
[0049] The free spectral range (FSR1) of the microring resonator is equal to the channel spacing of the arrayed waveguide grating, which is 0.4 nm, allowing the multiple wavelengths periodically transmitted by the microring resonator to be accurately separated by the arrayed waveguide grating.
[0050] According to embodiments of this disclosure, multiple microring resonators have different waveguide widths, forming staggered resonant wavelengths; wherein the interval between adjacent resonant wavelengths is 1 / 2 of the free spectral range of the microring resonator, as detailed in [see specific details]. Figure 3 As shown.
[0051] Figure 3 The transmission spectrum diagrams of two microring resonators with staggered resonant wavelengths according to embodiments of the present disclosure are schematically shown.
[0052] like Figure 3 As shown in the embodiments of this disclosure, the waveguide widths of the two microring resonators are set to be different, for example, 800nm and 805nm respectively, forming staggered resonant wavelengths, and the interval between adjacent resonant wavelengths is 1 / 2 of the free spectral range of the microring resonator, so as to obtain twice the number of wavelength sampling points within the same bandwidth range. In this way, the spectral sampling density is increased by 100% compared to a single microring resonator, thereby achieving higher resolution spectral measurement.
[0053] For example, a microring resonator with staggered resonator wavelengths can achieve twice the number of wavelength sampling points within the same bandwidth, doubling the spectral sampling density compared to a single microring resonator, thus doubling the spectral measurement resolution. If a single microring resonator is directly cascaded with an arrayed waveguide grating, achieving the same resolution would require an arrayed waveguide grating with 256 channels and a channel resolution of 0.2 nm, significantly increasing design and fabrication complexity. However, cascading two microring resonators with staggered resonant wavelengths with a 128-channel arrayed waveguide grating not only achieves high resolution and large bandwidth but also greatly reduces design and fabrication complexity.
[0054] In addition, in this embodiment of the disclosure, setting different waveguide widths of the microring resonator is also used to achieve the shift of the resonance peak, specifically the shift amount is 1 / 2 of the free spectral range, i.e., 0.2 nm.
[0055] According to embodiments of this disclosure, the arrayed waveguide grating includes: an input channel waveguide, an input planar waveguide region, an arrayed waveguide region, an output planar waveguide region, and an output channel waveguide, as detailed below. Figure 4 As shown.
[0056] Figure 4 A schematic diagram of an arrayed waveguide grating according to an embodiment of the present disclosure is shown.
[0057] like Figure 4 As shown, in the arrayed waveguide grating of this embodiment, the input channel waveguide is used to receive the composite optical signal with a free spectral range of 1 / 2 wavelength interval after the incident light passes through the micro-ring resonator.
[0058] The input planar waveguide region is used to diffract the composite optical signal.
[0059] The array waveguide region is used to generate a phase difference between optical signals of different wavelengths in the composite optical signal.
[0060] The output planar waveguide region is used to diffract the composite optical signal and focus optical signals of different wavelengths. Specifically, it focuses optical signals of different wavelengths into the corresponding output channel waveguide.
[0061] The output channel waveguide is used to output optical signals of a specific wavelength; that is, different output channel waveguides can output optical signals of different wavelengths.
[0062] According to embodiments of this disclosure, the channel spacing between different output channel waveguides is equal to the free spectral range of the microring resonator, so that multiple wavelengths periodically transmitted by the microring resonator can be accurately separated by the arrayed waveguide grating.
[0063] According to embodiments of this disclosure, the array waveguide region is connected to the input planar waveguide region and the output planar waveguide region respectively by tapered waveguides to reduce energy leakage and overall insertion loss of the device.
[0064] According to an embodiment of this disclosure, the array waveguide region is configured as a rectangular wiring configuration; wherein, the main part of the array waveguide region uses a wide waveguide for optical transmission, and the curved part of the array waveguide region uses a single-mode Euler curved waveguide for optical transmission, so as to reduce the excitation of higher-order modes.
[0065] In this embodiment of the disclosure, the arrayed waveguide grating satisfies the following expression:
[0066]
[0067] in, This represents the length difference between the arrayed waveguides in the arrayed waveguide grating; This represents the center wavelength of the arrayed waveguide grating, where the distance between the center wavelengths of two arrayed waveguide gratings is 1 / 2 the channel spacing of the arrayed waveguide grating; Represents the group refractive index; This represents the free spectral range (FSR2) of the arrayed waveguide grating, which satisfies the following expression:
[0068]
[0069] Where N represents the number of channels in the arrayed waveguide grating.
[0070] Figure 5 The transmission spectrum of an arrayed waveguide grating according to an embodiment of the present disclosure is schematically shown.
[0071] like Figure 5 As shown in this embodiment, the number of output channels of the arrayed waveguide grating can be, for example, 128, and the center wavelength spacing of the channels can be, for example, 0.4 nm. This embodiment selects the C+L band with a center wavelength of around 1550 nm for design, and designs 128 wavelength separation channels. The two arrayed waveguide gratings output a total of 256 channels for spectral resolution. Figure 5 The transmission spectral lines of a single arrayed waveguide grating are clearly displayed.
[0072] Due to unavoidable waveguide size deviations and material property inhomogeneities during the fabrication process, the actual resonant wavelength of the microring resonator differs from the design value, making it impossible to perfectly align with the channel center of the arrayed waveguide grating. Traditional methods such as thermal tuning or ion implantation require continuous power supply or additional complex processes. This disclosure, however, utilizes a segmented polarization method, employing a segmented periodic metal electrode arrangement system placed in the two straight waveguide regions of the microring resonator.
[0073] According to embodiments of this disclosure, the segmented periodic metal electrode arrangement system includes: a first metal electrode segment and a second metal electrode segment.
[0074] The first metal electrode segment is located in one of the straight waveguide regions of the microring resonator. The width of the first metal electrode segment is less than a preset threshold, that is, the width of each electrode segment of the first metal electrode segment is small, which is used to achieve fine-tuning of the wavelength.
[0075] The second metal electrode segment is located in another straight waveguide region of the microring resonator. The width of the second metal electrode segment is greater than a preset threshold, that is, the width of each electrode segment of the second metal electrode segment is relatively large, which is used to achieve coarse wavelength tuning.
[0076] According to embodiments of this disclosure, the tuning step of the first metal electrode segment is 0.01 nm to 0.04 nm, and the tuning step of the second metal electrode segment is 0.1 nm to 0.4 nm.
[0077] In this embodiment, segmented voltage polarization involves sequentially applying voltage polarization to the second metal electrode segment and the first metal electrode segment, causing the corresponding thin-film lead zirconate titanate waveguide to form a stable ferroelectric domain polarization region. The remanent polarization effect of the lead zirconate titanate material itself is used to non-volatilely change the refractive index of the locally polarized waveguide. The resonant wavelength of the microring resonator is monitored in real time using a spectrometer until it is precisely aligned with the center wavelength of the corresponding array waveguide grating channel, achieving an alignment accuracy of ±0.01 nm.
[0078] For example, voltages can be sequentially applied to tiny metal electrodes to cause the domains in the corresponding thin-film lead zirconate titanate waveguide to deflect in orientation, forming a stable ferroelectric domain polarization region. The residual polarization effect of the PZT material can then be used to change the refractive index of the polarized waveguide. Simultaneously, the two electrode segments with different metal widths in this embodiment can be used sequentially for coarse and fine wavelength tuning of the microring resonator, respectively, thereby achieving precise wavelength tuning. This "integral" tuning method, by sequentially polarizing multiple tiny electrode regions, can achieve non-volatile control of the resonant wavelength with a minimum precision of ±0.01 nm. Once alignment is complete, spectral measurement can be performed without continuous power supply, avoiding the high power consumption problem of traditional methods and significantly improving the long-term stability of the device.
[0079] In this embodiment, thin-film lead zirconate titanate, as a high-performance ferroelectric material, possesses unique non-volatile polarization characteristics. In its perovskite crystal structure, when the applied electric field exceeds the coercive field strength, Ti... 4+ / Zr 4+ The displacement of ions relative to the oxygen octahedron leads to the separation of positive and negative charge centers, resulting in polarization. After the electric field is removed, this polarization state, as residual polarization, can remain stable for a long time without continuous power supply. The residual polarization intensity of lead zirconate titanate affects its local refractive index. This non-volatile characteristic makes lead zirconate titanate an ideal material for achieving permanent refractive index modulation, offering significant advantages in fields such as optical non-volatile storage, programmable photonics, and low-power optoelectronic devices. It is particularly suitable for the permanent wavelength tuning of the micro-ring resonator in the integrated spectrometer of this invention. After alignment, it can maintain stable spectral measurement without continued power supply, thereby realizing a low-power, high-stability integrated spectral measurement system.
[0080] This disclosure also provides a method for preparing a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate, comprising: operations S1 to S6.
[0081] In operation S1, a silicon dioxide undercoat of a predetermined thickness (e.g., 2µm to 3µm) is deposited on a silicon substrate.
[0082] In operation S2, a lead zirconate titanate film of a predetermined thickness (e.g., 300 nm) is deposited on the silica undercoat using the sol-gel method.
[0083] In operation S3, microring resonators and arrayed waveguide gratings were fabricated based on lead zirconate titanate thin films using photolithography and inductively coupled plasma etching processes.
[0084] In operation S4, a metal electrode is deposited and patterned to strip out the desired metal electrode pattern.
[0085] In operation S5, a silicon oxide layer of a predetermined thickness (e.g., 1.2 μm) is deposited as the top cladding.
[0086] In operation S6, based on the upper cladding, silicon oxide windows are created using photolithography and inductively coupled plasma etching processes to expose the required metal electrodes for applying voltage polarization.
[0087] To make the fabrication method of the high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate in this disclosure clearer, a preferred embodiment will be specifically described below, see details. Figure 6 As shown.
[0088] Figure 6 The diagram illustrates a process flow chart of a method for fabricating a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate according to an embodiment of the present disclosure.
[0089] like Figure 6 As shown in the embodiments of this disclosure, for example, a thin film lead zirconate titanate substrate (hereinafter referred to as substrate) with a size of 25mm*25mm can be selected to be etched. The substrate structure can be a silicon substrate, a silicon dioxide underlayer (2um thick), and a thin film lead zirconate titanate layer (300nm thick) from bottom to top.
[0090] First, the substrate is cleaned. For example, acetone and ethanol can be used to ultrasonically clean the substrate for five minutes in sequence, and then it is dried with a nitrogen gun. After drying on a hot plate, negative photoresist is spin-coated. After photolithography and development, the pattern on the mask is successfully transferred to the first photoresist layer (i.e., photoresist 1).
[0091] Next, after hardening the film, inductively coupled plasma etching is performed along the first photoresist layer to transfer the pattern on the photoresist to the thin-film lead zirconate titanate waveguide. After forming a waveguide design pattern corresponding to the device layout, the residual photoresist is removed. Positive photoresist is then spin-coated to obtain the second photoresist layer (i.e., photoresist 2).
[0092] After photolithography and development, the desired metal pattern is transferred in reverse to the second photoresist layer; titanium / gold is deposited along the second photoresist layer, preferably with a metal thickness of titanium (10nm) + gold (500nm), and then lifted off to obtain a metal pattern corresponding to the device layout.
[0093] A 1.2µm silicon oxide cladding layer was deposited as a protective layer using plasma-enhanced chemical vapor deposition (PECVD) technology; then, positive photoresist was spin-coated to obtain a third photoresist layer.
[0094] Following photolithography and development, the desired exposed metal region pattern is transferred to the third photoresist layer. Inductively coupled plasma etching is then performed along the third photoresist layer to expose the required metal region for polarization. The spectrometer has an overall spectral measurement accuracy of 0.2 nm and a bandwidth of 51.2 nm.
[0095] The high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate disclosed herein can double the spectral sampling density under the same bandwidth. After non-volatile tuning, it can maintain the stability of spectral measurement without continuous power supply, realizing an integrated spectral measurement system with high resolution, large bandwidth and low power consumption, which is suitable for applications such as optical coherence tomography, biosensing imaging and optical communication.
[0096] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions. Those skilled in the art will understand that the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways, even if such combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments of this disclosure may be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.
[0097] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.
Claims
1. A high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate, characterized in that, The structure of the spectrometer includes: Substrate; A silicon dioxide undercoat layer is disposed on the substrate; A lead zirconate titanate thin film waveguide layer is disposed on the silicon dioxide under cladding, wherein the lead zirconate titanate thin film waveguide layer is provided with a plurality of micro-ring resonators and a plurality of arrayed waveguide gratings, and each arrayed waveguide grating is connected to each micro-ring resonator through a waveguide; A segmented periodic metal electrode arrangement system is provided in each straight waveguide region of the microring resonator; The plurality of microring resonators are configured with staggered resonant wavelengths, and the interval between adjacent resonant wavelengths is 1 / n of the channel interval of the array waveguide grating, where n represents the number of microring resonators or the array waveguide grating. The spectrometer is configured to change the local waveguide refractive index by utilizing the residual polarization effect of the lead zirconate titanate film through a segmented polarization method, so as to align the resonant wavelength with the center of the arrayed waveguide grating channel.
2. The spectrometer according to claim 1, characterized in that, The plurality of microring resonators are configured as racetrack-shaped microring resonators; Each racetrack-shaped microring resonator includes two semi-circular curved waveguides, two straight waveguides, and a directional coupler.
3. The spectrometer according to claim 2, characterized in that, The waveguide widths of the multiple microring resonators are different, forming an alternating distribution of the resonant wavelengths; The interval between adjacent resonant wavelengths is 1 / n of the free spectral range of the microring resonator.
4. The spectrometer according to claim 1, characterized in that, The arrayed waveguide grating includes: The input channel waveguide is used to receive a composite optical signal with a free spectral range and a wavelength interval of 1 / n after the incident light passes through the micro-ring resonator; An input planar waveguide region is used to diffract the composite optical signal; An arrayed waveguide region is used to generate a phase difference between optical signals of different wavelengths in the composite optical signal; The output planar waveguide region is used to diffract the composite optical signal and focus optical signals of different wavelengths; Output channel waveguide, used to output optical signals of a specific wavelength.
5. The spectrometer according to claim 4, characterized in that, The channel spacing between the output channel waveguides is equal to the free spectral range of the microring resonator, so that multiple wavelengths periodically transmitted by the microring resonator can be accurately separated by the arrayed waveguide grating.
6. The spectrometer according to claim 4, characterized in that, The array waveguide region is connected to the input planar waveguide region and the output planar waveguide region by tapered waveguides.
7. The spectrometer according to claim 6, characterized in that, The array waveguide region is configured as a rectangular wiring pattern. The main part of the array waveguide region uses a wide waveguide for optical transmission, while the curved part of the array waveguide region uses a single-mode Euler curved waveguide for optical transmission.
8. The spectrometer according to claim 1, characterized in that, The segmented periodic metal electrode arrangement system includes: A first metal electrode segment is disposed in one of the straight waveguide regions of the microring resonator, wherein the width of the first metal electrode segment is less than a preset threshold, for the purpose of achieving fine-tuning of the wavelength; The second metal electrode segment is located in another straight waveguide region of the microring resonator, wherein the width of the second metal electrode segment is greater than a preset threshold, and is used to achieve coarse wavelength tuning.
9. The spectrometer according to claim 8, characterized in that, The tuning step of the first metal electrode segment is 0.01 nm to 0.04 nm, and the tuning step of the second metal electrode segment is 0.1 nm to 0.4 nm.
10. A method for fabricating a high-resolution broadband integrated spectrometer based on thin-film lead zirconate titanate, characterized in that, The method includes: A silicon dioxide undercoat of a predetermined thickness is deposited on a silicon substrate; A lead zirconate titanate film of a predetermined thickness was deposited on the silica undercoat using the sol-gel method; Based on the aforementioned lead zirconate titanate thin film, a microring resonator and an arrayed waveguide grating were fabricated using photolithography and inductively coupled plasma etching processes. Deposit and pattern the metal electrode to strip it to obtain the desired metal electrode pattern; A silicon oxide layer of a predetermined thickness is deposited as the upper cladding layer; Based on the aforementioned cladding, silicon oxide windows are created using photolithography and inductively coupled plasma etching processes to expose the required metal electrodes for applying voltage polarization.