Ultraviolet to near-infrared ultra-wide band tunable WO 3-x Base FP cavity, preparation and control method

Abstract

This invention discloses a tunable WO3 with an ultra-wideband ultraviolet to near-infrared wavelength. 3‑x This paper describes the basic FP cavity, its fabrication, and its control methods, belonging to the field of optoelectronic device technology. The FP cavity consists of a substrate, a tungsten metal upper mirror, and a WO3 core. 3‑x The dielectric layers are stacked sequentially, with air serving as the lower reflector. During fabrication, a tungsten metal layer and a WO3 layer are deposited in an integrated manner via magnetron sputtering. 3‑x Dielectric layer, wherein WO 3‑x During the layer preparation stage, the volumetric flow ratio of argon to oxygen was precisely controlled at 2:1; during regulation, an annealing process of 200–500℃ and 0.5–2 h was used, by changing the WO3... 3‑x By adjusting the refractive index of the oxygen vacancy content in the layer, dynamic spectral tuning in the ultraviolet to near-infrared bands can be achieved, and the structural color in the visible light region can be simultaneously controlled. This technology does not require complex mechanical or voltage control structures and has advantages such as a wide tuning range, high stability, simple process, and suitability for mass production. It can be applied to fields such as optical communication, spectral analysis, and energy-saving windows.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic devices, and particularly relates to a UV-to-NIR super-wide-band tunable Fabry-Perot (FP) cavity with a WO 3-x as a dielectric layer and an annealing control method thereof. BACKGROUND

[0002] As the most widely used and mature dynamic wavelength selector in FP cavity technology, the core principle of the tunable Fabry-Perot (FP) filter is to change the resonance condition of the cavity by actively controlling the optical parameters (such as cavity length, medium refractive index or incident angle) of the FP cavity to realize continuous or discrete tuning of the transmission wavelength.

[0003] The resonance wavelength formula of the FP cavity is:

[0004] ;

[0005] wherein, n is the refractive index of the medium in the cavity, L is the cavity length, θ is the incident angle, m is the interference order; the essence of tuning is to change the three key parameters in the formula, n 、 L or θ This feature makes it irreplaceable in the fields of optical communication systems, tunable lasers, biomedical imaging and spectral analysis.

[0006] Among various tuning driving technology routes of existing tunable FP filters, the micro-electro-mechanical system (MEMS) electrostatic driving scheme is widely concerned due to its outstanding commercial prospects. This scheme changes the cavity length of the air cavity by pulling the movable mirror under the action of electrostatic force through the silicon-based micro-mirror cantilever structure, thereby realizing the resonance wavelength shift. However, this tuning method relying on mechanical movement has significant defects: on the one hand, the inherent attraction effect of the MEMS structure will strictly limit the tunable wavelength range, and the mechanical structure is extremely sensitive to vibration, resulting in a significant decrease in the long-term working stability of the device; on the other hand, in order to ensure the tuning accuracy, the process requirements for the flatness and stress control of the micro-mirror are extremely high, which significantly increases the processing difficulty and production cost of the device, and it is difficult to meet the requirements of some application scenarios that have strict requirements on stability and cost.

[0007] Compared with the technical route of changing the cavity length by mechanical movement, the scheme of realizing tuning by regulating the refractive index of the medium in the cavity shows better comprehensive performance: without complex mechanical structure, it not only has stronger anti-vibration interference ability and higher long-term stability, but also has simpler overall structure of the device, effectively reducing the processing difficulty and cost, becoming an important direction of the development of tunable FP filter technology. Under this technical background, research on the infrared electrochromic performance of multi-color tungsten oxide film has been carried out, and a FP cavity structure suitable for this performance has been proposed. The structure sputters tungsten (W) layer and tungsten trioxide (WO3) layer on the substrate in turn, modulates the resonance wavelength by controlling the thickness of the WO3 layer, and realizes continuous regulation of color in the visible light region. At the same time, the research also points out that the optical constants (n, k) of WO3 material can be adjusted at different voltages, so that the W / WO3 structure presents the color modulation effect of superimposing physical color and chemical color, providing a train of thought for the application of tungsten oxide-based materials in FP cavity tuning. However, this scheme still has obvious limitations: its spectral tuning relies on changing the thickness of the WO3 layer, and once the film thickness is prepared, it is difficult to dynamically adjust, and the operation convenience is poor; at the same time, the voltage regulation method needs to introduce electrodes and power supply modules, which not only increases the complexity of the device structure, but also may cause fluctuations in tuning accuracy due to uneven electric field distribution, making it difficult to meet the tuning requirements of wide band and high stability.

[0008] It is worth noting that non-stoichiometric tungsten oxide (WO 3-x ) as a derivative material of WO3 has more excellent photosensitivity and electron transport characteristics than pure WO3: not only the refractive index is higher, but also it has wide-spectrum absorption ability in the infrared band, which is an ideal candidate material for building tunable FP cavity medium layer. When WO3 is converted to WO 3-x , the material will spontaneously generate intrinsic defects such as oxygen vacancies and pentavalent tungsten atoms (W 5+ ). These defects can change the optical properties of the material through mechanisms such as localized states formed by inter-band transition electrons, surface dipoles of nanoparticle plasmon oscillations (accompanied by optical scattering), etc.; more importantly, if the content of oxygen vacancies can be quantitatively regulated through process means, the absorption and reflection spectra of WO 3-x material can be precisely adjusted, providing core support for wide-band tuning of FP cavity.

[0009] Therefore, if WO 3-x is used as the core medium layer of the FP cavity and its oxygen vacancy content can be regulated by a simple process to change the refractive index of the medium, it is expected to break through the limitations of existing technology and realize more stable and wider-band (such as ultraviolet to near-infrared) dynamic regulation of FP cavity spectrum, providing a new technical path for the performance upgrade and application expansion of tunable FP filter. So far, there is no WO 3-xThe related scheme of the medium layer and the FP cavity wide band tuning realized by the oxygen vacancy regulation has significant innovation space and application value. SUMMARY

[0010] The present application aims at solving the problems in the prior art, and provides a WO 3-x base FP cavity, a preparation method and a regulation method. The present application takes non-stoichiometric tungsten oxide (WO 3-x ) as the core medium layer of the FP cavity, combines with a simple annealing process to regulate the oxygen vacancy content, realizes the dynamic regulation of the FP cavity medium refractive index, finally achieves the wide spectrum tunable from ultraviolet to near infrared, and has the advantages of simple device structure, strong anti-interference ability and high stability, and meets the needs of the wide band, high stability tunable optical device in the fields of optical communication, spectrum analysis, energy saving window and the like.

[0011] In order to realize the above technical purpose, the present application is realized by the following technical scheme: a WO 3-x base FP cavity from ultraviolet to near infrared super wide band, comprising a substrate, a tungsten metal layer and a WO 3-x medium layer which are sequentially stacked; the tungsten metal layer serves as an upper mirror, and air serves as a lower mirror; the thickness of the tungsten metal layer is 80-130 nm, and the thickness of the WO 3-x medium layer is 160-220 nm.

[0012] Further, the surface roughness Ra of the tungsten metal layer is 1.5-1.8 nm, and the tungsten metal layer is in a crystalline state by XRD characterization; and the WO 3-x medium layer is in an amorphous state by XRD characterization.

[0013] The preparation method of the above-mentioned WO 3-x base FP cavity from ultraviolet to near infrared super wide band is as follows:

[0014] 1) Pretreatment of the substrate;

[0015] 2) Fixing the substrate on a magnetron sputtering base;

[0016] 3) Preparation of the tungsten metal layer: pre-sputtering of a 99.95% high-purity tungsten target; the sputtering chamber is vacuumed to ≤5*10 -4 Pa, 99.99% high-purity argon is introduced, the gas pressure is adjusted to 0.55-0.75 Pa, the direct current reaction magnetron sputtering is started, the sputtering power is 180-230 W, the deposition temperature is 25-27℃, the sputtering current is 350-500 mA, the sputtering voltage is 450-540 V, and the tungsten metal layer on the substrate has a thickness of 80-130 nm until the sputtering is stopped;

[0017] 4) WO3-x Preparation of the medium layer: without destroying the vacuum environment of the chamber, switch to 99.99% high-purity argon and oxygen mixed gas, the volume flow ratio of Ar and O2 is 2:1, adjust the gas pressure to 0.65~0.7 Pa, and stabilize for 5~10 min; start the direct current reaction magnetron sputtering, set the power to 70~100 W, the deposition temperature to 25~27℃, the sputtering current to 120~150 mA, and the sputtering voltage to 520~580 V, and sputter the tungsten metal layer to form a WO 3-x Stop sputtering when the film thickness reaches 160~220 nm, cool to room temperature after keeping the chamber in a vacuum state, and then take out the sample.

[0018] Further, in step 3), the pre-sputtering power is 130~170 W, and the pre-sputtering time is 4~10 min.

[0019] The application also discloses a WO 3-x FP cavity and a method for adjusting the WO 3-x FP cavity, and the specific steps are as follows: annealing the WO 3-x FP cavity, the annealing temperature is 200~500℃, the annealing time is 0.5~2 h; by adjusting the annealing temperature, the oxygen vacancy content in the medium layer is changed, and then the refractive index of the WO 3-x FP cavity is adjusted, and the spectral tunability of the WO 3-x FP cavity is realized in the ultraviolet to near-infrared wave band.

[0020] Further, in the 400 nm~900 nm wave band, the WO 3-x FP cavity corresponding to the same wavelength decreases with the increase of the annealing temperature; in the 1400 nm~2000 nm wave band, the WO 3-x FP cavity corresponding to the same wavelength increases with the increase of the annealing temperature.

[0021] Further, the adjusting method can realize the structural color tuning of the WO 3-x FP cavity in the visible light region, and with the increase of the annealing temperature, the structural color of the WO 3-x FP cavity continuously changes from purple to dark green.

[0022] The application has the following beneficial effects:

[0023] 1. The application constructs a tunable FP cavity with WO 3-x as the core medium layer, changes the medium refractive index by adjusting the oxygen vacancy content through annealing, realizes the dynamic tuning of the spectrum in the ultraviolet to near-infrared wave band, breaks through the wave band limitation of the traditional MEMS mechanical tuning (the wavelength range is limited) and WO3 voltage tuning; at the same time, the WO 3-xThe material’s infrared broadband absorption characteristics enable the device to maintain stable reflectivity modulation in the near-infrared long-wave region, meeting the full-band coverage requirements of optical communication, spectral analysis and other fields, and significantly improving the tuning range compared to existing technologies.

[0024] 2. Amorphous WO3 3-x Reduce light scattering loss and improve spectral tuning smoothness; the crystalline tungsten layer ensures high reflectivity and enhances the interference effect of the FP cavity; combined with an asymmetric structure with air as the lower reflector, it avoids the problem of multiple interference order overlap in traditional symmetric FP cavities, which is more conducive to precise wavelength selection;

[0025] 3. This application uses the physical mechanism of "oxygen vacancy-refractive index" for tuning, which eliminates the need for complex moving parts and fundamentally solves the vibration sensitivity problem of MEMS mechanical tuning. The device can still maintain stable spectral characteristics under external vibration environment.

[0026] 4. The control process can be achieved through conventional annealing (200℃~500℃), without the need for complex voltage control or mechanical drive systems, which reduces equipment costs. Furthermore, the annealing parameters (temperature and time) are easy to control precisely, and samples can be controlled synchronously in batches, facilitating industrial mass production.

[0027] 5. The FP cavity structure constructed in this application achieves ultraviolet-near-infrared spectral tuning while simultaneously controlling the visible light region structural color of the device (such as a continuous change from purple to dark green), breaking through the limitation of traditional FP cavities that only focus on spectral performance. This feature makes the device likely to be directly applied to the field of energy-saving windows that coordinate lighting and appearance management, which can reduce building energy consumption and meet appearance design requirements, effectively expanding application scenarios. Attached Figure Description

[0028] Figure 1 An atomic force microscope (AFM) image of the W-reflector layer in the FP cavity prepared in Example 1;

[0029] Figure 2 This is a schematic diagram of the structure of the ultra-wideband tunable FP cavity from ultraviolet to near infrared prepared in Example 1;

[0030] Figure 3 The W film prepared in Example 1 and the WO film 3-x X-ray diffraction (XRD) pattern of the film;

[0031] Figure 4 For WO under different annealing conditions 3-x High-resolution W4f X-ray photoelectron spectroscopy (XPS) spectrum of the film, where A corresponds to unannealed W4f. 3-x XPS high-resolution W4f spectrum of the film, B corresponds to WO after annealing at 300℃ for 1 h. 3-xXPS high resolution W4f spectrum of the film layer, C corresponds to WO 3-x XPS high resolution W4f spectrum of the film layer, D corresponds to WO 3-x XPS high resolution W4f spectrum of the film layer;

[0032] Figure 5 The WO 3-x The refractive index of the film layer changes with the wavelength;

[0033] Figure 6 The WO 3-x The extinction coefficient of the film layer changes with the wavelength;

[0034] Figure 7 The FP cavity reflection spectrum of the unannealed and annealed at different temperatures;

[0035] Figure 8 A is the real structure color chart of the FP cavity sample of the unannealed and annealed at different temperatures, B is the reflection spectrum corresponding to the visible light region. DETAILED DESCRIPTION

[0036] The following examples further illustrate the content of the present application, but should not be understood as limiting the present application. Modifications and replacements of the method, steps or conditions of the present application, without departing from the essence of the present application, all belong to the scope of the present application.

[0037] Example 1

[0038] This example discloses a ultraviolet to near-infrared super wide band tunable Fabry-Perot (FP) cavity, the specific preparation process is as follows:

[0039] S1: rinse the front and back of the transparent quartz substrate with deionized water, 15 s for each side, 5 times for each side;

[0040] S2: soak the transparent quartz substrate in analytical pure acetone (the liquid surface covers the substrate), gently shake for 10 s, then take out, rinse the front and back with acetone spray for 5 s each, 3 times for each side; immediately rinse the front and back of the substrate with ultrapure water for 1 time (to avoid the mixing of acetone and isopropyl alcohol (IPA) used in the subsequent stage to produce flocculent residues); soak the substrate in analytical pure IPA, shake for 10 s, then take out, rinse the front and back with IPA spray for 5 s each, 3 times for each side, to remove surface oil stains;

[0041] S3: rinse the front and back of the transparent quartz substrate with ultrapure water for 20 s each side, rinse 3 times on each side; after rinsing, tilt the substrate at 45° and let it drip naturally for 10 s, observe whether a continuous and uniform water film is formed on the surface: if the water film has no breakpoints, the cleanliness is up to standard, if water droplets appear, re-execute S3 to avoid unqualified substrates entering the subsequent process;

[0042] S4: use high-purity nitrogen gas, the gun mouth is 10-15 cm away from the substrate, blow dry the surface water stains along the edge to the center at an angle of 45°;

[0043] S5: use heat-resistant tape to fix the transparent quartz substrate on the magnetron sputtering base;

[0044] S6: pre-sputter the 99.95% high-purity tungsten target (power 150 W, time 5 min) to remove the oxide layer on the target surface; the vacuum degree of the sputtering chamber is ≤5×10 -4 Pa, introduce 99.99% high-purity argon gas, adjust the gas pressure to 0.65 Pa; start the direct current reaction magnetron sputtering, set the power to 200 W, the deposition temperature to 25℃, the sputtering current to 400 mA, and the sputtering voltage to 502 V, stop sputtering when the tungsten reflective layer on the transparent quartz substrate reaches 100 nm in thickness;

[0045] Figure 1 The atomic force microscope (AFM) image of the W reflective layer prepared in step S6 is shown in the figure. As can be seen from the figure, the W film layer surface particles are uniformly distributed, and its roughness Ra is 1.7 nm, showing good surface flatness.

[0046] S7: without damaging the vacuum environment of the chamber, switch to the 99.99% high-purity argon and oxygen channel, accurately control the volume flow ratio of Ar and O2 to be 2:1 through the mass flow controller, adjust the gas pressure to 0.65 Pa, and stabilize for 5 min; start the direct current reaction magnetron sputtering, set the power to 80 W, the deposition temperature to 25℃, the sputtering current to 140 mA, and the sputtering voltage to 565 V, sputter the tungsten reflective layer to form a WO 3-x thin film with a thickness of 200 nm; keep the chamber in a vacuum state and cool to room temperature, then take out the sample to avoid high-temperature oxidation of the WO 3-x film.

[0047] Figure 2 The structure diagram of the tunable FP cavity prepared in step S7 is shown in the figure. This structure uses WO 3-x as the dielectric layer, semi-reflective metal tungsten (W) as the upper mirror, and air as the lower mirror, together with the transparent quartz substrate to form an asymmetric FP cavity.

[0048] Figure 3 The W film layer and WO 3-xX-ray diffraction (XRD) patterns of the film layers. Among them, WO 3-x The corresponding curve has no obvious sharp diffraction peak, showing a broad diffuse characteristic, which is amorphous; the corresponding curve of W has obvious and sharp diffraction peaks, showing good crystallinity.

[0049] S8: The FP cavity structure prepared in step S7 is placed in a 99.99% high-purity argon atmosphere (gas pressure 90-110 Pa), and annealing treatment is performed at 300°C, 400°C and 500°C for 1 h respectively.

[0050] Figure 4 Among them, A-D are respectively the FP cavity sample before annealing, after 300°C annealing for 1 h, after 400°C annealing for 1 h, and after 500°C annealing for 1 h, WO 3-x XPS high-resolution W4f spectrum of the film layer. By peak fitting (distinguishing W 6+ and W 5+ , the corresponding characteristic peaks) can be seen: before annealing, W 5+ and W 6+ , the relative content ratio (W 5+ / W 6+ ) is 2.00%; as the annealing temperature increases from 300°C to 500°C, the ratio increases to 5.98%, 8.34%, and 8.94% respectively, showing a gradually increasing trend. Since the formation of W 5+ is closely related to the generation of oxygen vacancies in WO 3-x , it can be inferred that more oxygen vacancies will be generated in the WO 3-x film layer as the annealing temperature increases.

[0051] Figure 5 The refractive index of the WO 3-x film layer changes with the wavelength under different annealing conditions, and the four curves correspond to the samples before annealing, 300°C annealing for 1 h, 400°C annealing for 1 h, and 500°C annealing for 1 h respectively. As can be seen from the figure, in the wavelength range of about 400 nm-900 nm, the refractive index of the WO 3-x film layer decreases as the annealing temperature increases; in the wavelength range of about 1400 nm-2000 nm, the refractive index increases as the annealing temperature increases.

[0052] The cause of this phenomenon is inferred as follows: in the visible light band, the free carrier effect is weak, and the refractive index of the material is mainly dominated by lattice polarization and inter / intra-band transition. Before annealing, WO 3-xOxygen vacancies in the film layer mostly exist as random point defects. These point defects strongly scatter electrons and introduce a large number of localized defect states that can be excited by visible light into the band gap, thereby generating additional polarizability and increasing the refractive index n. During annealing, heat treatment causes oxygen vacancies to migrate and aggregate, forming a more ordered extended defect structure (such as crystal shear planes). In this ordered structure, the electrons "contributed" by oxygen vacancies can be more efficiently localized within the channels of the extended defects, not only reducing the number of defect states in the band gap or making their distribution more concentrated, but also reducing the scattering of visible light. As the random defect states that mainly contribute to the polarizability in the visible light region decrease, the polarizability of the material in the visible light region weakens, ultimately leading to a decrease in the refractive index n. In the near-infrared band, the free carrier effect dominates. The free electrons introduced by oxygen vacancies increase the concentration of free electrons inside the material, thereby triggering the localized surface plasmon resonance (LSPR) effect, enhancing the interaction between light and material, which is equivalent to an increase in the refractive index n.

[0053] Figure 6 To test WO under different annealing conditions 3-x The extinction coefficient of the film varies with wavelength. As shown in the figure, in the 350 nm to 450 nm wavelength range, WO... 3-x The extinction coefficient of the film decreases rapidly with increasing wavelength. At the same wavelength, the extinction coefficient of the film gradually increases with increasing annealing temperature (300℃, 400℃, 500℃). After entering the visible-near infrared band (approximately 450 nm to 2000 nm), the extinction coefficient of the WO3-x film increases with increasing wavelength and then gradually stabilizes. The extinction coefficient corresponding to the same wavelength still increases with increasing annealing temperature.

[0054] This phenomenon is mainly attributed to: WO 3-xThe oxygen vacancies in the film layer can introduce defect energy levels in the band gap, which reduces the effective optical band gap of the material, allowing lower energy photons to be absorbed, which is one of the core mechanisms of the extinction coefficient. In the 350 nm-450 nm waveband, the extinction coefficient is mainly derived from interband transition and defect state absorption. During the annealing process, the migration and ordering reconstruction of oxygen vacancies (such as the formation of crystal shear surfaces) reduce some randomly distributed defect states, but the ordered extended defect structure easily induces the reconstruction and concentration of defect energy levels, or enhances the probability of interband transition, so that the combined absorption effect of defect state absorption and interband transition is enhanced with the increase of annealing temperature. Therefore, the extinction coefficient in this waveband gradually increases with the increase of annealing temperature. In the visible-near infrared waveband, the dominant mechanism of the extinction coefficient changes to free carrier absorption. With the increase of annealing temperature, on the one hand, the oxygen vacancy concentration is further improved, and on the other hand, the ordered defect structure optimizes the free carrier transport characteristics, which significantly enhances the free carrier absorption effect, and then leads to the rapid increase of the extinction coefficient in this waveband with the increase of annealing temperature until it tends to be stable.

[0055] Figure 7 The reflection spectra of the FP cavity before and after annealing at different temperatures are shown in the figure. It can be seen from the figure that the unannealed sample has a significant reflection peak; with the annealing temperature gradually increasing from 300°C to 500°C, the reflection peak value of the sample gradually decreases, and the peak position of the reflection peak is blue-shifted to the ultraviolet band (from 535 nm to 435 nm); at the same time, in the long wave region (such as the near-infrared band), the reflectivity shows an upward trend with the increase of annealing temperature, and the reflection spectra under different annealing temperatures are obviously different, which reflects the effective regulation of the annealing temperature on the optical properties of the FP cavity.

[0056] Figure 8 A is the actual structure color diagram of the sample obtained under different annealing conditions, and B is the reflection spectrum in the visible light region (300-800 nm). As can be seen from A, the unannealed sample is purple, the sample annealed at 300°C is yellow-green, the sample annealed at 400°C is green, and the sample annealed at 500°C is dark green; combined with the reflection spectrum of B, the position, intensity and profile of the reflection peak under different annealing temperatures are significantly different, which shows that the annealing temperature can effectively regulate the reflection characteristics of the FP cavity, and then realize the tunable change of the structural color in the visible light region.

[0057] The above results show that the annealing treatment of the prepared FP cavity at different temperatures can regulate the WO 3-xThe oxygen vacancy content in the film layer; the change of the oxygen vacancy content will further change the refractive index of the medium, thereby realizing the spectral tunable regulation from ultraviolet to near infrared band. At the same time, with the change of the oxygen vacancy content, the sample presents a significant structural color change, which makes it have potential application value in the field of energy-saving window technology facing "lighting-active light energy management".

[0058] The basic principles, main features and advantages of the present application are shown and described above. However, the above description is only a specific embodiment of the present application, and the technical features of the present application are not limited thereto. Any other embodiments obtained by those skilled in the art without departing from the technical solutions of the present application should be covered in the scope of the present application.

Claims

1. A tunable WO in the ultraviolet to near-infrared ultrawide band 3-x The base FP cavity is characterized by, Includes a substrate, a tungsten metal layer, and WO3 stacked sequentially. 3-x Dielectric layer; The tungsten metal layer serves as the upper reflector, and the air serves as the lower reflector; The thickness of the tungsten metal layer is 80~130 nm, and the WO 3-x The thickness of the dielectric layer is 160~220 nm.

2. The ultraviolet to near-infrared ultrawideband tunable wavelength distribution (WO) as described in claim 1 3-x The base FP cavity is characterized by, The surface roughness Ra of the tungsten metal layer is 1.5~1.8 nm, and the tungsten metal layer is characterized by a crystalline state by XRD; the WO 3-x The dielectric layer was characterized as amorphous by XRD.

3. The ultraviolet to near-infrared ultrawideband tunable WO as described in any one of claims 1-2 3-x The method for preparing the FP cavity is characterized in that, Includes the following steps: 1) Substrate pretreatment; 2) Fix the substrate onto the magnetron sputtering substrate; 3) Preparation of the tungsten metal layer: Pre-sputtering of a 99.95% high-purity tungsten target; evacuating the sputtering chamber to a vacuum level ≤5×10⁻⁶. -4 Pa, introduce 99.99% high-purity argon gas, and adjust the gas pressure to 0.55~0.75 Pa; Start DC reactive magnetron sputtering with a sputtering power of 180~230 W, a deposition temperature of 25~27℃, a sputtering current of 350~500 mA, and a sputtering voltage of 450~540 V until the thickness of the tungsten metal layer on the substrate reaches 80~130 nm. 4) WO 3-x Preparation of the dielectric layer: Without disrupting the vacuum environment of the chamber, switch to a mixture of 99.99% high-purity argon and oxygen, with an Ar to O2 volume flow rate ratio of 2:1, adjust the gas pressure to 0.65~0.7 Pa, and stabilize for 5~10 min; start DC reactive magnetron sputtering, setting the power to 70~100 W, deposition temperature to 25~27℃, sputtering current to 120~150 mA, and sputtering voltage to 520~580 V, and deposit WO3 on the tungsten metal layer. 3-x Sputtering is stopped when the film thickness reaches 160~220 nm. The sample is removed after cooling to room temperature while maintaining a vacuum in the chamber.

4. The ultraviolet to near-infrared ultrawideband tunable WO as described in claim 3 3-x The method for preparing the FP cavity is characterized in that, In step 3), the pre-sputtering power is 130~170 W and the pre-sputtering time is 4~10 min.

5. A tunable WO in the ultraviolet to near-infrared band as described in any one of claims 1-2 3-x The method for controlling the FP cavity is characterized by, Includes the following steps: For the WO 3-x The FP cavity is annealed at a temperature of 200-500℃ for 0.5-2 hours. The WO3 content is adjusted by regulating the annealing temperature. 3-x The oxygen vacancy content in the dielectric layer, thereby regulating WO3 3-x The refractive index of the dielectric layer to achieve WO 3-x The spectrum of the base FP cavity is tunable in the ultraviolet to near-infrared band.

6. The ultraviolet to near-infrared ultrawideband tunable WO as described in claim 5 3-x The method for controlling the FP cavity is characterized by, Within the 400 nm to 900 nm wavelength range, the corresponding WO 3-x The refractive index of the dielectric layer decreases with increasing annealing temperature; within the 1400 nm to 2000 nm wavelength range, the WO3 corresponding to the same wavelength... 3-x The refractive index of the dielectric layer increases with increasing annealing temperature.

7. The ultraviolet to near-infrared ultrawideband tunable WO as described in claim 5 3-x The method for controlling the FP cavity is characterized by, The aforementioned control method can achieve WO 3-x The FP cavity exhibits structural color harmony in the visible light region, and the WO... 3-x The structural color of the base FP cavity changes continuously from purple to dark green.

Images