Low-absorption optical dielectric film preparation technology

Abstract

The invention provides a low-absorption optical dielectric film preparation technology, and relates to the field of optical film preparation, a film preparation device comprises a sealing box body, a radiant panel, a sample fixing frame and a heating element, the radiant panel is arranged in the sealing box body and forms a sample chamber in a surrounding mode, and the radiant panel is made of oxide materials corresponding to doping elements in a film; the sample fixing frame is arranged in the sample chamber and is used for fixing a to-be-treated film; the heating element is arranged on the outer side of the sample chamber and used for heating the radiant panel. According to the low-absorption optical dielectric film preparation device, a stable treatment environment is provided through the sealed box body, selective heating is conducted through the metal oxide radiant panel matched with the doped elements, activation of the doped elements can be promoted, meanwhile, the heat influence on the film body is reduced, unnecessary crystallization or defect generation is avoided, and the production efficiency is improved. The optical performance of the film is improved.

Description

Technical Field

[0001] The present application relates to the field of optical film manufacturing technology, and in particular to a low-absorption optical medium film preparation technology. Background Art

[0002] As laser technology advances toward higher power and longer lifespans, absorption losses in optical thin films have become a core bottleneck restricting system performance. During prolonged, high-power continuous laser irradiation, even small absorption losses can cause light energy and heat to conduct and accumulate within the thin film, leading to damage to the film's components. Absorption losses in optical thin films also cause significant energy losses during laser generation, transmission, and beam conversion. For complex laser systems, this energy loss can attenuate the incident laser energy to unacceptable levels. Consequently, the preparation of ultra-low absorption films is gaining increasing attention.

[0003] Commonly used ultra-low absorption films are multilayer systems composed of alternating high-refractive-index materials (such as Ta2O5 and TiO2) and low-refractive-index materials (such as SiO2). Heat treatment is a common post-processing process for thin films, and annealing can alter their microstructure, optical properties, and stress characteristics. However, for high-refractive-index films doped with other elements (such as Ti in Ta2O5), excessively high annealing temperatures can lead to film crystallization, impairing the film's optical properties. Excessively low annealing temperatures make it difficult to activate the Ti element, and the optical performance will fall short of expectations. Summary of the Invention

[0004] In view of this, the present application proposes a low-absorption optical medium film preparation technology to solve the problem mentioned in the background technology of the mismatch between the annealing temperature requirements of the doping elements and the high-refractive film layer.

[0005] The technical solution of this application is achieved as follows:

[0006] In one aspect, the present application provides a low-absorption optical medium thin film preparation device, comprising:

[0007] Sealed box;

[0008] A radiation plate is disposed in the sealed box and surrounds the sample chamber, wherein the radiation plate is made of an oxide material corresponding to the doping element in the film;

[0009] A sample fixing rack is provided in the sample chamber and is used to fix the film to be processed;

[0010] The heating element is arranged outside the sample chamber and is used to heat the radiation plate.

[0011] Based on the above technical solution, preferably, the oxide material includes a stable oxide and / or a metastable oxide of the doping element.

[0012] Based on the above technical solution, preferably, the radiation plate has a thickness of 5-20 mm and a porosity of 50% to 70%.

[0013] On the basis of the above technical solution, preferably, it also includes a ceramic protective cover with an opening at the top, the ceramic protective cover is arranged in a sealed box, the radiation plate is installed on the inner bottom surface of the ceramic protective cover, the radiation plate and the inner bottom surface of the ceramic protective cover are surrounded to form a sample chamber, there is an annular gap between the ceramic protective cover and the radiation plate, a heating chamber is formed between the ceramic protective cover and the inner wall of the sealed box, and a plurality of heating elements are provided, which are evenly distributed in the heating chamber.

[0014] On the basis of the above technical solution, preferably, it further includes a thermal insulation sleeve with an opening at the top, which is located inside the sealed box and is sleeved on the outside of the ceramic protective sleeve, forming a heating chamber between the thermal insulation sleeve and the ceramic protective sleeve.

[0015] Based on the above technical solution, preferably, there is at least one temperature sensor inside the sample chamber.

[0016] On the basis of the above technical solution, preferably, the sealed box body includes a box body and a box cover, the top of the box body is open, the box cover is detachably arranged on the top of the box body, the ceramic protective cover and the thermal insulation cover are arranged in the box body from the inside to the outside, the side wall of the box body is provided with an air inlet interface, the thermal insulation cover is provided with an air inlet channel connected to the air inlet interface and the heating chamber, the side wall of the ceramic protective cover is provided with an air guide channel connected to the air inlet channel, the top surface of the radiation plate is lower than the top surface of the ceramic protective cover, and a guide channel is formed between the radiation plate and the box cover, and the guide channel connects the air guide channel and the sample chamber for introducing oxygen into the sample chamber.

[0017] On the basis of the above technical solution, preferably, a plug-in portion is fixedly provided on the inner bottom surface of the ceramic protective sleeve, and the bottom surface of the radiation plate has a plug-in groove matched with the plug-in portion.

[0018] In a second aspect, the present application discloses a method for heat treating an optical film, which uses the optical film heat treating apparatus described in the first aspect, and includes the following steps:

[0019] S1. Select an oxide material corresponding to the doping element of the thin film to prepare a radiation plate, install it in a sealed box to form a sample chamber, and install the film to be treated in the sample chamber;

[0020] S2. heating the radiation plate by a heating element so that it emits characteristic infrared radiation;

[0021] S3, using characteristic infrared radiation to selectively excite doping elements in the film;

[0022] S4. Control the heat treatment temperature to rearrange the doping element sites while the main material remains amorphous.

[0023] On the basis of the above technical solution, preferably, the heat treatment temperature control in step S4 includes the following stages:

[0024] In the first stage, the temperature is heated to 280-320°C at a heating rate of 80-120°C / h and kept at this temperature for 6-10 hours;

[0025] In the second stage, continue heating at a heating rate of 80-120℃ / h to 480-520℃ and keep warm for 8-12 hours;

[0026] The third stage is cooling at a cooling rate of 40-60℃ / h to 330-370℃ and then cooling naturally;

[0027] Among them, each stage emits characteristic infrared radiation through the radiation plate, so that the selective heat absorption of the doped elements in the film reaches 1.5-3 times that of the main material.

[0028] Compared with the prior art, this application has the following beneficial effects:

[0029] (1) The low-absorption optical medium film preparation device disclosed in the present application provides a stable processing environment through a sealed box and uses an oxide radiation plate that matches the doping element for selective heating, which can promote the activation of the doping element while reducing the thermal impact on the film body, avoiding unnecessary crystallization or defects, and improving the optical properties of the film.

[0030] (2) By introducing the ceramic protective cover and optimizing the arrangement of the heating elements, the thermal field is homogenized and the thermal efficiency is improved. The annular gap and heating chamber design of the ceramic protective cover effectively reduce the thermal stress and ensure that the heat is evenly transferred to the radiation plate. In addition, the ceramic protective cover, on the one hand, effectively blocks the short-wave infrared radiation generated by the heating element, preventing high-energy photons from directly acting on the sample to cause non-selective heating and film damage. On the other hand, the ceramic protective cover forms a thermal buffer area through its annular gap structure, effectively regulating the reverse heat radiation transfer of the radiation plate, avoiding the resistance characteristic drift and oxidation acceleration problems of the heating element due to excessive temperature, and ensuring the temperature control accuracy and element service life.

[0031] (3) By introducing a thermal insulation sleeve and forming a heating chamber together with a ceramic protective sleeve, the thermal efficiency of the heating system is improved and the temperature stability is optimized. The low thermal conductivity of the thermal insulation sleeve reduces heat loss, making the temperature distribution in the heating chamber more uniform while reducing energy consumption. This design further enhances the thermal field control capability during the film preparation process, ensuring that the heat received by the radiation plate is more stable and uniform, thereby improving the doping uniformity and optical performance of the film, and ultimately obtaining a high-quality low-absorption optical dielectric film.

[0032] (4) By optimizing the structure of the sealed box and the gas circulation path, precise control of the atmosphere in the sample chamber is achieved. The preheating and uniform distribution of the gas in the heating chamber ensures a stable oxidative environment for the film during high-temperature treatment, thereby improving the activation efficiency of the doping elements and optimizing the chemical balance of the metal-oxygen bonds in the film. This technical solution is particularly suitable for the preparation of low-absorption optical films that require oxidative atmosphere treatment, and can effectively reduce the defect density of the film and improve its optical performance and long-term stability.

[0033] (5) A plug-in portion is fixedly provided on the inner bottom surface of the ceramic protective sleeve, and the bottom surface of the radiation plate has a plug-in slot that matches the plug-in portion. Through the plug-in structure design, the positioning accuracy of the radiation plate is ensured while achieving a quick replacement function. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 This is a schematic diagram of the three-dimensional structure of the low-absorption optical medium film preparation device disclosed in this application;

[0036] Figure 2 This is a schematic planar structural diagram of the low-absorption optical medium film preparation device disclosed in this application;

[0037] Figure 3 for Figure 2 Plane section view at AA in the middle;

[0038] Reference numerals:

[0039] 1. Sealed box body; 11. Box body; 12. Box cover; 2. Radiant plate; 111. Sample chamber; 3. Sample holder; M. Film; 4. Heating element; 5. Ceramic protective cover; 6. Insulation cover; 112. Heating chamber; 7. Temperature sensor; 10. Air inlet interface; 61. Air inlet channel; 51. Air guide channel; P. Guide channel; 113. Connector; 21. Connector slot. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] like Figure 1 As shown, combined Figure 2-3 The embodiment of the present application discloses a low-absorption optical medium film preparation device, which includes a sealed box 1, a radiation plate 2, a sample fixing frame 3 and a heating element 4.

[0042] The sealed chamber 1 forms the foundation of the device, providing a closed processing environment. Its tightness effectively isolates ambient air and impurities, preventing contamination and oxidation of the film during preparation, thereby improving its optical properties. The chamber's design ensures a controlled environment throughout the entire process, providing stable conditions for subsequent heating and radiation treatments.

[0043] The radiation plate 2 is placed within the sealed housing 1, surrounding the sample chamber 111. Its material is made of the oxide corresponding to the doping element in the film. The key to this design is that the radiation plate 2 not only serves as a heat transfer medium for heating, but also, because its material matches the doping element in the film, it emits infrared radiation of a specific wavelength during the heating process, thereby achieving selective heating of the film. This selective heating promotes the activation of the doping element while minimizing thermal effects on the film itself, preventing unnecessary crystallization or defects.

[0044] Specifically, if the thin film Ta2O5 is doped with Ti, the radiation plate 2 uses TiO2 (TiO x ) is prepared, when the thin film HfO2 is doped with Nb element, the radiation plate 2 uses Nb2O5.

[0045] The sample holder 3 is located within the sample chamber 111 and is used to secure the film M to be processed. Its design ensures that the film remains stable during the heating process, preventing deformation or damage to the film due to mechanical vibration or thermal stress. In some embodiments, the sample holder 3 can be configured as a holder with a slot into which the film is inserted or clipped, or the sample holder 3 can be configured with clamping members to clamp the film on both sides.

[0046] Heating element 4, located outside sample chamber 111, heats radiant plate 2. This heating method differs from direct film heating. Instead, it indirectly heats the film by heating radiant plate 2, generating heat radiation that then transfers heat through radiation. This indirect heating method provides a more uniform temperature distribution and reduces the risk of localized overheating, thereby improving film preparation quality.

[0047] In this embodiment, the heating element 4 may be a heating wire.

[0048] In this embodiment, the radiation plate 2 uses the same oxide as the doping element of the thin film (for example, if the thin film is doped with Ti, the radiation plate 2 uses TiO2). This homologous material design allows the infrared photon energy emitted by the radiation plate 2 when heated to be highly matched to the electronic energy level transition requirements of the doping element. Taking the TiO2 radiation plate 2 as an example, its lattice vibration (phonon mode) produces strong infrared radiation in the 2.5-5μm band, and the photon energy in this band (0.25-0.5eV) just corresponds to the TiO2 radiation plate 2. 3+ / Ti 40+ When these characteristic infrared photons act on the film, they are preferentially absorbed by the Ti-doped sites, triggering localized electron transitions, thereby selectively activating the vibration of the Ti-O bond (rather than the entire Ta3O5 host lattice), achieving "targeted energy injection."

[0049] During heating, the characteristic infrared radiation emitted by the radiation plate 2 penetrates the film surface, but only the specific chemical bonds of the doping element (such as Ti) can efficiently absorb these photons. This absorption leads to a localized non-thermal equilibrium state at the doping site: 1. Activation of the doping element: After the Ti-O bond resonates and absorbs photons, the bond angle undergoes a transient distortion (Jahn-Teller effect), making it easier for Ti ions to diffuse into the lattice interstitial sites, promoting doping uniformity; 2. Matrix protection mechanism: Because the vibration frequency of the Ta-O bond (~15THz) does not match the emission spectrum of the radiation plate 2, the host lattice only receives a small amount of thermal energy through secondary phonon scattering, thus maintaining the amorphous state.

[0050] The low-absorption optical medium film preparation device disclosed in the present application provides a stable processing environment through a sealed box 1, and uses an oxide radiation plate 2 that matches the doping element for selective heating to promote the activation of the doping element. The device can effectively reduce the absorption loss of the film and improve the optical performance, while avoiding the problems of crystallization or thermal stress of the film body that may be caused by traditional direct heating methods. It is suitable for the preparation of high-quality optical films.

[0051] In this embodiment, the oxide material of the radiation plate 2 is a stoichiometric oxide or a non-stoichiometric oxide corresponding to the doping element.

[0052] Stoichiometric oxides refer to oxides in which the atomic ratio of an element to oxygen strictly conforms to its chemical formula, such as TiO2 (Ti:O=1:2). This type of material has a definite main structure and stable physical and chemical properties, and can provide stable infrared radiation characteristics when heated at high temperatures. Taking TiO2 as an example, its lattice vibration and electronic energy level structure produce characteristic radiation within a specific wavelength range (such as 2.5-5μm), which is highly matched with the absorption characteristics of the Ti doping element, thereby achieving selective heating. This matching can efficiently activate the doping sites in the film while reducing the thermal impact on the base material.

[0053] Non-stoichiometric oxides refer to oxides whose atomic ratio of an element to oxygen deviates from its standard chemical formula, such as TiO (Ti:O=1:1), Ti2O3 (Ti:O=2:3), etc. Due to the presence of oxygen vacancies or interstitial atoms, the electronic structure and lattice vibration mode of such materials may be different from those of stoichiometric oxides, which may produce richer radiation characteristics. For example, the Ti in TiO 2+ Ion supply and Ti 4+ Different electron transition energy levels (in TiO2) extend the emissivity of the radiation plate 2 within a specific wavelength range. This characteristic allows for the selection of more suitable non-stoichiometric oxides based on the specific needs of film doping to further optimize the selective heating effect.

[0054] By allowing the use of stoichiometric or non-stoichiometric oxides, greater flexibility is provided in the choice of the material of the radiative plate 2 .

[0055] For example: for high stability and high valence doping elements (such as Ti 4+ ) can be selected as stoichiometric oxides (such as TiO2). 2+ 、Ti 3+ ), non-stoichiometric oxides (such as TiO or Ti2O3) can be selected. This flexibility allows the device to adapt to different doping systems and process requirements, thereby improving the doping uniformity and optical performance of the film.

[0056] By limiting the material of the radiant plate 2 to either stoichiometric or non-stoichiometric oxides of the doping element, a more precise range of material selection is provided. Stoichiometric oxides ensure stable radiation characteristics, while non-stoichiometric oxides may offer more optimized radiation performance through their unique electronic and lattice structures. This technical solution makes the selective heating process more targeted and flexible, adapting to the requirements of different doping elements and process conditions while maintaining low absorption performance of the film, thereby improving the doping effect and optical quality of the film.

[0057] In some embodiments, the thickness of the radiation plate 2 is 5-20 mm. This configuration provides the radiation plate 2 with sufficient thermal capacity to buffer power fluctuations of the heating element 4 and ensure temperature stability in the sample chamber 111. This thickness also avoids the problem of reduced heating rate caused by excessively thick materials (>20 mm).

[0058] In this embodiment, the porosity of the radiation plate 2 is 50% to 70%. The unique physical mechanism of the porous structure achieves triple optimization: First, the multiple scattering effect generated by the pore interfaces narrows the radiation spectrum, significantly enhancing its match with the characteristic absorption peak of the dopant element; second, the pore network forms a controllable thermal resistance, maintaining a high temperature on the radiating surface while reducing the thermal load on the substrate; and finally, this pore range optimizes the stress distribution on the pore walls, maintaining structural stability at high temperatures. This synergistic effect enables the radiation plate 2 to efficiently excite the dopant element while preventing overheating and structural deformation of the substrate, ultimately achieving the production of low-absorption, highly uniform thin films.

[0059] In some embodiments, the preparation apparatus of the present application further includes a ceramic protective sleeve 5 with an open top. The ceramic protective sleeve 5 is disposed within a sealed housing 1, and the radiant plate 2 is mounted on the inner bottom surface of the ceramic protective sleeve 5. The radiant plate 2 and the inner bottom surface of the ceramic protective sleeve 5 surround and form a sample chamber 111. This structure makes the spatial layout of the sample chamber 111 more compact and controlled. An annular gap is provided between the ceramic protective sleeve 5 and the radiant plate 2. The design of this gap allows for uniform heat diffusion while avoiding thermal stress concentration caused by direct contact between the radiant plate 2 and the protective sleeve.

[0060] A heating chamber 112 is formed between the ceramic protective sleeve 5 and the inner wall of the sealed housing 1. Multiple heating elements 4 are evenly distributed within the heating chamber 112. This arrangement allows heat generated by the heating elements 4 to be indirectly transferred to the radiant plate 2 through the ceramic protective sleeve 5, forming a uniform annular thermal field. The ceramic protective sleeve 5 is made of materials (such as alumina or silicon nitride) with high thermal stability and low thermal conductivity, which allows it to withstand high temperatures while reducing heat loss to the exterior of the sealed housing 1, thereby improving heating efficiency.

[0061] By introducing a ceramic protective sleeve 5 and optimizing the layout of the heating elements 4, a uniform thermal field is achieved and thermal efficiency is improved. The annular gap within the ceramic protective sleeve 5 and the design of the heating chamber 112 effectively reduce thermal stress while ensuring uniform heat transfer to the radiant plate 2. The symmetrical distribution of the multiple heating elements 4 further enhances temperature control accuracy. This technical solution significantly reduces thermal non-uniformity during film preparation, improves the activation efficiency of dopant elements, and reduces film defects caused by temperature fluctuations, ultimately resulting in low-absorption, high-performance optical dielectric films.

[0062] In addition, the ceramic protective cover 5 achieves dual protection for the sample and the heating element 4 through its alumina material and annular gap design: on the one hand, it effectively blocks the short-wave infrared radiation generated by the heating element 4, preventing high-energy photons from directly acting on the sample to cause non-selective heating and film damage, while only allowing long-wave thermal radiation to pass through; on the other hand, the ceramic protective cover 5 forms a thermal buffer area through its annular gap structure, effectively regulating the reverse heat radiation transfer of the radiation plate 2, avoiding the resistance characteristic drift and accelerated oxidation problems of the heating element 4 due to excessive temperature, and ensuring the temperature control accuracy and component service life.

[0063] As some embodiments, the preparation device of the present application further includes a thermal insulation sleeve 6 with an opening at the top.

[0064] The insulation sleeve 6 is positioned outside the ceramic protective sleeve 5, forming a heating chamber 112 therebetween for accommodating the heating element 4. The insulation sleeve 6 is designed with an open top, which not only ensures a heat transfer path between the heating element 4 and the ceramic protective sleeve 5, but also prevents excessive heat loss from within the sealed housing 1. The insulation sleeve 6 is typically constructed of a refractory material with low thermal conductivity (such as ceramic fiber or zirconia), which effectively reduces heat diffusion to the exterior of the sealed housing 1, thereby maintaining temperature stability within the heating chamber 112.

[0065] Heating chamber 112 is formed by the space between insulation jacket 6 and ceramic protective jacket 5, with heating elements 4 evenly distributed within this chamber. The introduction of insulation jacket 6 provides a more enclosed thermal environment within heating chamber 112, reducing external interference with the heating process. Furthermore, the low thermal conductivity of insulation jacket 6 concentrates heat within heating chamber 112, avoiding energy waste and improving heating efficiency.

[0066] By introducing the insulation sleeve 6, which together with the ceramic protective sleeve 5 forms the heating chamber 112, the heating system's thermal efficiency and temperature stability are improved. The low thermal conductivity of the insulation sleeve 6 reduces heat loss, resulting in a more uniform temperature distribution within the heating chamber 112 and lowering energy consumption. This design further enhances thermal field control during film preparation, ensuring more stable and uniform heat received by the radiant plate 2. This improves the film's doping uniformity and optical performance, ultimately resulting in high-quality, low-absorption optical dielectric films.

[0067] In this embodiment, at least one temperature sensor 7 is located within the sample chamber 111. Temperature sensor 7 is positioned directly within the sample chamber 111 and accurately measures the actual temperature of the film's surroundings. The placement of this sensor must take into account the distribution characteristics of the thermal radiation field. It can be installed near the sample holder 3 or at a key point on the inner wall of the radiation plate 2 (e.g., at the area with the highest heat flux). The temperature sensor 7 can be a thermocouple, infrared sensor, or fiber optic sensor, with the specific selection requiring a balance between measurement accuracy and high-temperature resistance.

[0068] In terms of process control: sensor data is fed back to the temperature control system in real time, and the power of the heating element 4 is dynamically adjusted (PID control algorithm) to control the temperature fluctuation of the sample chamber 111 within the range of ±1°C.

[0069] By integrating a temperature sensor 7 inside the sample chamber 111, accurate real-time temperature measurement of the film preparation environment is achieved. This design not only improves the response speed and stability of temperature control, but also optimizes thermal field uniformity through data-driven closed-loop regulation, ultimately ensuring the repeatability of the doping effect and low-absorption characteristics of the optical film.

[0070] As some implementation methods, the sealed box 1 of this embodiment includes a box body 11 and a box cover 12. The top of the box body 11 is open, and the box cover 12 is hinged to the box body 11. This detachable design facilitates sample loading and maintenance.

[0071] The ceramic protective sleeve 5 and the thermal insulation sleeve 6 are positioned sequentially within the chamber body 11, forming a double-layered sleeve structure. The space between the thermal insulation sleeve 6 and the ceramic protective sleeve 5 forms a heating chamber 112, which accommodates the heating element 4. The inner side of the ceramic protective sleeve 5 and the radiant plate 2 together form a sample chamber 111, which is used to place the film to be processed.

[0072] In this embodiment, the side wall of the box body 11 is also provided with an air inlet port 10 for connecting to an external gas source, specifically oxygen. The insulation sleeve 6 is provided with an air inlet channel 61 that communicates with the air inlet port 10 and the heating chamber 112, through which gas enters the heating chamber 112. The side wall of the ceramic protective sleeve 5 is provided with an air guide channel 51 that communicates with the air inlet channel 61 and is used to guide gas from the heating chamber 112 to the top of the radiation plate 2. Because the top surface of the radiation plate 2 is lower than the top surface of the ceramic protective sleeve 5, a guide channel P is formed between the radiation plate 2 and the box cover 12. This channel connects the air guide channel 51 with the sample chamber 111, ultimately evenly delivering oxygen to the sample chamber 111.

[0073] The design of the gas flow path ensures that the gas is fully preheated before entering the sample chamber 111. The gas enters through the gas inlet port 10, absorbs heat released by the heating element 4 as it flows through the heating chamber 112, and then enters the sample chamber 111 through the gas guide channel 51 and the flow channel P. This process not only prevents the cold gas from directly impacting the film surface, but also improves the temperature uniformity of the gas through heat exchange, thereby reducing thermal stress on the film.

[0074] In this embodiment, the role of oxygen introduction is mainly reflected in two aspects: 1. Oxidation control of doping elements: For some metal-doped oxide films (such as Ti-doped Ta2O5), the introduction of oxygen can control the valence state of the doping elements (such as Ti 3+ →Ti 4+ ), thereby optimizing the optical band gap and absorption characteristics of the film; 2. Defect repair: Oxygen can combine with oxygen vacancies in the film at high temperatures, reducing non-radiative recombination centers and lowering the absorption loss of the film.

[0075] By optimizing the structure and gas circulation path of the sealed housing 1, precise control of the atmosphere within the sample chamber 111 is achieved. The preheating and uniform distribution of gas within the heating chamber 112 ensures a stable oxidizing environment for the film during high-temperature treatment, thereby improving the activation efficiency of the dopant element and optimizing the stoichiometric balance of the metal-oxygen bond in the film. This technical solution is particularly suitable for the preparation of low-absorption optical films requiring oxidizing atmosphere treatment, effectively reducing film defect density and improving their optical performance and long-term stability.

[0076] To enable detachable and replaceable radiating panel 2, this embodiment features a fixed inserting portion 113 on the inner bottom surface of ceramic protective sleeve 5. The bottom surface of radiating panel 2 has an inserting slot 21 that mates with inserting portion 113. This plug-in design ensures precise positioning of radiating panel 2 while enabling rapid replacement.

[0077] The technical advantages of the replaceable design are: 1. Process adaptability: For different doping systems (such as Ta2O5:Ti and HfO2:Nb), matching radiation plates 2 (TiO2 plates and Nb2O5 plates) can be quickly replaced, reducing replacement time. 2. Maintenance convenience: Damaged or aged radiation plates 2 can be replaced individually, reducing equipment maintenance costs.

[0078] The present application also discloses a method for preparing a low-absorption optical medium film, comprising the following steps:

[0079] S1. Select an oxide material corresponding to the doping element of the thin film to prepare a radiation plate 2, install it in a sealed box 1 to form a sample chamber 111, and install the thin film to be treated in the sample chamber 111;

[0080] S2. The radiation plate 2 is heated by the heating element 4 so as to emit characteristic infrared radiation.

[0081] When heated to the working temperature, the narrow-band infrared spectrum emitted by the radiation plate 2 (such as the characteristic peak of TiO2 at 4.1 μm) and the doping element (Ti 3+ / Ti 4+ )'s dd transition absorption bands overlap, forming a selective energy transfer channel.

[0082] S3. Use characteristic infrared radiation to selectively excite the doping elements in the film. The physical essence of selective excitation is local resonant energy transfer. After the characteristic infrared photons are preferentially absorbed by the doping elements, the following microscopic processes are triggered: electronic excitation of the doping sites (such as Ti 3+ →Ti 4+ +e - ), enhancing ion mobility; intensifying local lattice vibration, reducing diffusion barriers; reducing the oxygen vacancy migration barrier, promoting defect repair.

[0083] S4. Control the heat treatment temperature to rearrange the dopant element sites while maintaining the amorphous state of the main material. By precisely adjusting the heat treatment parameters, the dopant element is fully activated, the main material is maintained in a metastable state, and the interface stress is controlled.

[0084] By precisely matching the characteristic infrared radiation emitted by the radiation plate 2 with the energy levels of the dopant element, the dopant element preferentially absorbs heat and undergoes local activation, promoting its orderly distribution and optimized coordination structure within the film. This selective heating mechanism achieves efficient doping of the dopant element while avoiding crystallization of the host material, significantly reducing the film's optical absorption losses and ultimately resulting in a high-performance, low-absorption optical dielectric film.

[0085] This application further refines the heat treatment temperature control process, and achieves deep activation of doping elements and progressive optimization of thin film structure through the synergistic effect of multi-stage gradient temperature control and selective radiation heating.

[0086] Phase 1: Preheating at 280-320°C, using a moderate heating rate of 80-120°C / h, gradually releases internal stress in the film and stimulates the initial diffusion activity of the dopant element. Holding for 6-10 hours allows the dopant element (such as Ti) to form a preliminary complex structure (Ti-V_O complex) with oxygen vacancies, laying the structural foundation for subsequent high-temperature treatment.

[0087] The second stage: activation at 480-520°C, maintaining the same heating rate to allow the dopant element to acquire sufficient kinetic energy for lattice migration. During the 8-12 hours of holding, the selective heating effect of the characteristic infrared radiation (the dopant element absorbs 1.5-3 times the heat of the matrix) drives the following microscopic processes: Ti ions migrate to low-energy sites, oxygen vacancies are arranged in an orderly manner around the dopant element (forming a stable Ti-4V_O configuration), and the main amorphous network undergoes local reconstruction, optimizing the short-range atomic arrangement while maintaining the overall disorder.

[0088] The third stage, gradient cooling, uses a slow cooling rate of 40-60°C / h to suppress thermal stress and complete structural freezing in the critical temperature range of 330-370°C. The natural cooling stage utilizes the residual heat of the radiation plate 2 to maintain temperature uniformity, ensuring that the final occupancy of the doping elements meets the stoichiometric ratio requirements.

[0089] By precisely matching the characteristic infrared radiation emitted by the radiation panel with the energy levels of the doping elements, selective energy transfer is achieved at each stage of the film's thermal treatment, allowing the doping element sites to absorb 1.5-3 times the amount of heat absorbed by the matrix material. This targeted energy injection mechanism prioritizes activation energy for the doping ions, significantly enhancing their diffusion and migration capabilities. Furthermore, by precisely controlling the energy distribution ratio, it ensures the full activation and orderly distribution of the doping elements while avoiding overheating and crystallization of the matrix material, ultimately achieving the synergistic optimization of doping efficiency and film optical properties.

[0090] By synergizing a three-stage temperature program with selective radiation, the entire process of doping element optimization, from initial activation and deep migration to final positioning, is achieved. This method achieves high doping uniformity in the film while maintaining extremely low intrinsic absorption. Its stepped thermal treatment design is particularly suitable for the mass production of high-precision optical components.

[0091] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A low-absorption optical medium film preparation device, characterized in that: include: Sealed box (1); A radiation plate (2) is disposed in the sealed box (1) and surrounds the sample chamber (111), wherein the radiation plate (2) is made of an oxide material corresponding to the doping element in the thin film; A sample fixing frame (3) is arranged in the sample chamber (111) and is used to fix the film to be processed; The heating element (4) is arranged outside the sample chamber (111) and is used to heat the radiation plate (2).

2. The low-absorption optical medium thin film preparation device according to claim 1, characterized in that: The oxide material of the radiation plate (2) is a stoichiometric oxide or a non-stoichiometric oxide corresponding to the doping element.

3. The low-absorption optical medium thin film preparation device according to claim 2, wherein: The radiation plate (2) has a thickness of 5-20 mm and a porosity of 50% to 70%.

4. The low-absorption optical medium thin film preparation device according to claim 1, wherein: The invention also includes a ceramic protective cover (5) with an opening at the top, wherein the ceramic protective cover (5) is arranged in a sealed box body (1), and the radiation plate (2) is installed on the inner bottom surface of the ceramic protective cover (5). The radiation plate (2) and the inner bottom surface of the ceramic protective cover (5) surround and form a sample chamber (111). There is an annular gap between the ceramic protective cover (5) and the radiation plate (2), and a heating chamber (112) is formed between the ceramic protective cover (5) and the inner wall of the sealed box body (1). A plurality of heating elements (4) are provided and are evenly distributed in the heating chamber (112).

5. The low-absorption optical medium thin film preparation device according to claim 4, characterized in that: It also includes a heat-insulating sleeve (6) with an opening at the top, which is sleeved on the outside of the ceramic protective sleeve (5), and a heating chamber (112) is formed between the heat-insulating sleeve (6) and the ceramic protective sleeve (5).

6. The low-absorption optical medium thin film preparation device according to claim 1, wherein: At least one temperature sensor (7) is provided inside the sample chamber (111).

7. The low-absorption optical medium thin film preparation device according to claim 5, characterized in that: The sealed box (1) comprises a box body (11) and a box cover (12). The box body (11) has an opening at the top. The box cover (12) is detachably arranged on the top of the box body (11). The ceramic protective cover (5) and the thermal insulation cover (6) are arranged in the box body (11) from the inside out. The side wall of the box body (11) is provided with an air inlet interface (10). The thermal insulation cover (6) is provided with an air inlet channel (61) connected to the air inlet interface (10) and the heating chamber (112). The side wall of the ceramic protective cover (5) is provided with an air guide channel (51) connected to the air inlet channel (61). The top surface of the radiation plate (2) is lower than the top surface of the ceramic protective cover (5). A flow guide channel (P) is formed between the radiation plate (2) and the box cover (12). The flow guide channel (P) connects the air guide channel (51) and the sample chamber (111) and is used to introduce oxygen into the sample chamber (111).

8. The low-absorption optical medium thin film preparation device according to claim 4, wherein: The inner bottom surface of the ceramic protective sleeve (5) is fixedly provided with an inserting portion (113), and the bottom surface of the radiation plate (2) has an inserting groove (21) that matches the inserting portion (113).

9. A method for preparing a low-absorption optical medium film, characterized in that: The low-absorption optical medium film preparation device according to any one of claims 1 to 8 comprises the following steps: S1. Select an oxide material corresponding to the doping element of the thin film to prepare a radiation plate, install it in a sealed box to form a sample chamber, and install the film to be treated in the sample chamber; S2. heating the radiation plate by a heating element so that it emits characteristic infrared radiation; S3, using characteristic infrared radiation to selectively excite doping elements in the film; S4. Control the heat treatment temperature to rearrange the doping element sites while the main material remains amorphous.

10. The method for preparing a low-absorption optical medium film according to claim 9, wherein: The heat treatment temperature control in step S4 includes the following stages: In the first stage, the temperature is heated to 280-320°C at a heating rate of 80-120°C / h and kept at this temperature for 6-10 hours; In the second stage, continue heating at a heating rate of 80-120℃ / h to 480-520℃ and keep warm for 8-12 hours; The third stage is cooling at a cooling rate of 40-60℃ / h to 330-370℃ and then cooling naturally; Among them, each stage emits characteristic infrared radiation through the radiation plate, so that the selective heat absorption of the doped elements in the film reaches 1.5-3 times that of the main material.

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