Wide tuning filter waveguide and method of making same

Abstract

The present application relates to the technical field of optoelectronic devices, and particularly relates to a wide tuning filter waveguide and a preparation method thereof. The filter waveguide comprises an insulating substrate, a bottom electrode layer and a transparent dielectric layer are prepared on the top of the insulating substrate in sequence, an optical waveguide groove is prepared on the transparent dielectric layer, a refractive index adjusting layer is prepared on the transparent dielectric layer in a direction perpendicular to the optical waveguide groove, the refractive index adjusting layer is filled with a filling material having a refractive index greater than that of the insulating substrate to form a filling layer, a top electrode layer is prepared on the filling layer, the refractive index adjusting layer is made of an electro-optic material, and the wide tuning of the reflection spectrum or the transmission spectrum of the filter waveguide is realized by changing the refractive index of the electro-optic material. The present application utilizes the electro-optic material, and the change of the refractive index of the electro-optic material under the control of voltage or current is more than one thousand times of the change of the refractive index of a common semiconductor device or electro-optic material, so that the present application has the characteristic of wide tuning range.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic device technology, and in particular to a wide-tunable filter waveguide and its fabrication method. Background Technology

[0002] Tunable filter waveguides achieve tuning by changing the refractive index of the material through current injection or thermal changes, or by controlling the voltage to produce a small change in the refractive index of a material with electro-optic effects. Typical techniques include incorporating current, voltage, or thermal control into waveguides made of materials such as Si, InP, GaAs, and lithium niobate to achieve wavelength tuning.

[0003] Among the aforementioned technologies, tunable filter waveguides achieved through thermal changes have a slow response speed, typically on the order of 10 μs, with a tuning range of 3 nm to 5 nm per 100 °C. Tunable filter waveguides achieved through current injection have a faster response speed, on the order of nanoseconds, but a smaller tuning range, typically on the order of 1 to 2 nm, making it impossible to achieve wide-spectrum tuning. Materials with voltage-controlled electro-optic effects also suffer from the problem of insufficient refractive index change, making it difficult to achieve wide-spectrum tuning; the electro-optic coefficient of these materials is generally around 10. -5 ~10 -6 A voltage of 100 volts can change the refractive index by 0.1 to 0.01. The tuning range of the tunable filter waveguide is usually below 5 nm, and electrical isolation and control become difficult under high voltage conditions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a wide-tunable filter waveguide and its fabrication method. It uses electrochromic materials and phase change materials. Under appropriate control, these two materials can drastically change the real part of the refractive index, thereby achieving a very wide tuning range and a filtering effect of tens or even hundreds of nanometers, thus significantly improving the working range of the tunable filter waveguide.

[0005] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0006] This invention proposes a wide-tunable filtering waveguide, comprising an insulating substrate, a bottom electrode layer and a transparent dielectric layer sequentially formed on the top of the insulating substrate, an optical waveguide groove formed on the transparent dielectric layer, and refractive index adjustment layers arranged at intervals on the transparent dielectric layer perpendicular to the optical waveguide groove. A leveling layer is formed by leveling the refractive index adjustment layers and the optical waveguide groove with a leveling material having a refractive index greater than that of the insulating substrate. A top electrode layer is formed on the leveling layer. The refractive index adjustment layers are electro-phase change materials or electrochromic materials. By changing the refractive index of the electro-phase change material or electrochromic material, wide tuning of the reflection spectrum or transmission spectrum of the filtering waveguide is achieved.

[0007] Preferably, the electro-phase change material is VO2, V2O5, germanium antimony tellurium, molybdenum telluride, or titanium antimony tellurium, and the electrochromic material is tungsten oxide, molybdenum oxide, or nickel oxide.

[0008] Preferably, the refractive index adjustment layers are arranged to form a Bragg grating, a sampling grating, a phase-shifting grating, or an equivalent phase-shifting grating pattern.

[0009] The present invention proposes a method for fabricating a wide-tunable filter waveguide, comprising the following steps:

[0010] S1. Prepare a bottom electrode layer on an insulating substrate;

[0011] S2. Prepare a transparent dielectric layer on the bottom electrode layer;

[0012] S3. Fabricate an optical waveguide groove on a transparent dielectric layer;

[0013] S4. A refractive index adjustment layer is prepared on the transparent dielectric layer in a direction perpendicular to the optical waveguide groove. The refractive index adjustment layer is an electro-phase change material or an electrochromic material. By changing the refractive index of the electro-phase change material or the electrochromic material, a wide tuning of the filtered waveguide reflection spectrum or transmission spectrum can be achieved.

[0014] S5. A leveling material is used to fill the refractive index adjustment layer and the optical waveguide groove to form a leveling layer.

[0015] S6. Prepare the top electrode layer on the filler layer.

[0016] Preferably, the electro-phase change material or electrochromic material is prepared into a refractive index adjustment layer by evaporation, photolithography or etching, or the electro-phase change material or electrochromic material is incorporated into a material with photosensitive properties and then prepared into a refractive index adjustment layer by photolithography, development and baking.

[0017] Preferably, VO2 nanoparticles are incorporated into PMMA to prepare a VO2-doped suspension as an electro-phase change material. A PMMA film doped with VO2 nanoparticles is formed on a transparent dielectric layer by photolithography, development and baking. The PMMA film is arranged into a Bragg grating, sampling grating, phase shift grating or equivalent phase shift grating pattern.

[0018] Another wide-tunable filtering waveguide proposed in this invention includes a conductive substrate, a bottom electrode layer fabricated at the bottom of the conductive substrate, a transparent dielectric layer fabricated at the top of the conductive substrate, an optical waveguide groove etched on the transparent dielectric layer, a refractive index adjustment layer fabricated on the transparent dielectric layer perpendicular to the optical waveguide groove, a leveling layer formed by leveling the refractive index adjustment layer and the optical waveguide groove using a leveling material with a refractive index lower than that of the conductive substrate, and a top electrode layer fabricated on the leveling layer. The refractive index adjustment layer is an electro-phase change material or an electrochromic material. By changing the refractive index of the electro-phase change material or the electrochromic material, wide tuning of the reflection spectrum or transmission spectrum of the filtering waveguide is achieved.

[0019] Preferably, the electro-phase change material is VO2, V2O5, germanium antimony tellurium, molybdenum telluride, or titanium antimony tellurium, and the electrochromic material is tungsten oxide, molybdenum oxide, or nickel oxide.

[0020] Preferably, the refractive index adjustment layers are arranged to form a Bragg grating, a sampling grating, a phase-shifting grating, or an equivalent phase-shifting grating pattern.

[0021] Another method for fabricating a wide-tunable filter waveguide proposed in this invention includes the following steps:

[0022] S1. Prepare a bottom electrode layer on the bottom of the conductive substrate;

[0023] S2. Prepare a transparent dielectric layer on top of the conductive substrate;

[0024] S3. Fabricate an optical waveguide groove on a transparent dielectric layer;

[0025] S4. A refractive index adjustment layer is prepared on the transparent dielectric layer in a direction perpendicular to the optical waveguide groove. The refractive index adjustment layer is an electro-phase change material or an electrochromic material. By changing the refractive index of the electro-phase change material or the electrochromic material, a wide tuning of the filtered waveguide reflection spectrum or transmission spectrum can be achieved.

[0026] S5. A leveling material is used to fill the refractive index adjustment layer and the optical waveguide groove to form a leveling layer.

[0027] S6. Prepare the top electrode layer on the filler layer.

[0028] Preferably, the electro-phase change material or electrochromic material is prepared into a refractive index adjustment layer by evaporation, photolithography or etching, or the electro-phase change material or electrochromic material is incorporated into a material with photosensitive properties and then prepared into a refractive index adjustment layer by photolithography, development and baking.

[0029] Preferably, VO2 nanoparticles are incorporated into PMMA to prepare a VO2-doped suspension as an electro-phase change material. A PMMA film doped with VO2 nanoparticles is formed on a transparent dielectric layer by photolithography, development and baking. The PMMA film is arranged into a Bragg grating, sampling grating, phase shift grating or equivalent phase shift grating pattern.

[0030] Compared with the prior art, the beneficial effects that the present invention can achieve are as follows:

[0031] 1. By utilizing electro-phase change materials or electrochromic materials, under voltage or current control, the change in refractive index is more than a thousand times that of ordinary semiconductor devices or electro-optic effect materials. Therefore, it has the characteristic of a wide tuning range and is expected to expand the current tuning range of less than 5 nanometers to tens or even hundreds of nanometers.

[0032] 2. Utilizing semiconductor technology for large-scale mass production offers advantages such as high stability, high consistency, ease of batch production, high yield, and low cost. The coating, photolithography, and electrode fabrication processes used are fully compatible with traditional semiconductor processes, allowing for processing on existing production lines. This enables the entire filter waveguide to be chip-based, thereby improving the success rate of fabrication and reducing costs and prices. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the wide tuned filter waveguide provided in Embodiment 1 of the present invention;

[0034] Figures 2-5 This is a schematic diagram of the fabrication process of the wide tuned filter waveguide provided in Embodiment 1 of the present invention.

[0035] The reference numerals in the figures include: insulating substrate 1, bottom electrode layer 2, transparent dielectric layer 3, refractive index adjustment layer 4, leveling layer 5, top electrode layer 6, and optical waveguide groove 7. Detailed Implementation

[0036] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0038] Figure 1 The structure of the wide tuned filter waveguide provided according to Embodiment 1 of the present invention is shown.

[0039] like Figure 1 As shown, the wide-tunable filter waveguide provided in Embodiment 1 of the present invention includes an insulating substrate 1, a bottom electrode layer 2, a transparent dielectric layer 3, a refractive index adjustment layer 4, a leveling layer 5, a top electrode layer 6, and an optical waveguide groove 7. The insulating substrate 1 serves as the carrier of the entire wide-tunable filter waveguide, and the bottom electrode layer 2, the transparent dielectric layer 3, the refractive index adjustment layer 4, the leveling layer 5, the top electrode layer 6, and the optical waveguide groove 7 are respectively fabricated on the insulating substrate 1.

[0040] The insulating substrate 1 can be a glass substrate.

[0041] The bottom electrode layer 2 is used to prepare the top of the insulating substrate 1, and can be made of a metal material such as silver.

[0042] A transparent dielectric layer 3 is sequentially fabricated on top of the bottom electrode layer 2. The transparent dielectric layer 3 is made of a dielectric material that is transparent in the working band. Under current conditions, it also needs to have a certain electron or hole transport capability. Under voltage conditions, it also needs to have electrical insulation properties, such as SiO2 material.

[0043] The optical waveguide groove 7 is fabricated on the transparent dielectric layer 3 by photolithography or etching, and the optical waveguide groove 7 serves as a channel for incident light.

[0044] The refractive index adjustment layer 4 is made of an electrochromic material or an electrochromic material. The electrochromic material or electrochromic material is prepared on the transparent dielectric layer 3 by evaporation, photolithography or etching to form the refractive index adjustment layer 4. Alternatively, the electrochromic material or electrochromic material can be incorporated into a material with photosensitive properties and prepared on the transparent dielectric layer 3 by photolithography, development and baking to form the refractive index adjustment layer 4. The refractive index adjustment layer 4 is perpendicular to the optical waveguide groove 7. The refractive index adjustment layer 4 is arranged in a specific pattern on the transparent dielectric layer 3 and has specific high reflection or high transmission characteristics for a certain wavelength or several wavelengths, thereby achieving a filtering effect.

[0045] Electro-phase change materials include, but are not limited to, VO2, V2O5, germanium-antimony-tellurium, molybdenum telluride, and titanium-antimony-tellurium phase change materials. Electrochromic materials include, but are not limited to, tungsten oxide, molybdenum oxide, and nickel oxide. Electro-phase change materials or electrochromic materials maintain their volume and thickness under the influence of current or voltage, but their properties change, with a drastic change in the real part of the refractive index. Therefore, they can alter the peak position of the reflection or transmission spectrum of a wide-tunable filter waveguide.

[0046] The leveling layer 5 can be made of undoped PMMA material, which is spin-coated over a large area above the transparent dielectric layer 3 to fill the refractive index adjustment layer 4 and the optical waveguide groove 7, thereby reducing the loss during photon transmission in the waveguide. The refractive index of the leveling material is lower than that of the insulating substrate 1.

[0047] The top electrode layer 6 is prepared on top of the filling layer 5, and can be a metallic material such as silver.

[0048] When the wide-tunable filter waveguide is working, the lower electrode and the top electrode layer 6 are energized. By changing the refractive index of the electro-phase change material or the electrochromic material through voltage or current, the refractive index of the electro-phase change material or the electrochromic material changes greatly under the control of voltage or current, resulting in a wide range of changes in the reflection spectrum or transmission spectrum of the wide-tunable filter waveguide, thereby achieving a wide-tunable filtering effect.

[0049] Figures 2-5 The fabrication process of the wide tuned filter waveguide provided in Embodiment 1 of the present invention is shown respectively.

[0050] like Figures 2-5 As shown, the steps of the fabrication method of the wide-tuned filter waveguide provided in Embodiment 1 of the present invention are as follows:

[0051] First, metallic silver is prepared as the bottom electrode layer 2 on an insulating substrate 1 (glass substrate), and a transparent dielectric layer 3 of SiO2 material is prepared on the bottom electrode layer 2.

[0052] Secondly, the optical waveguide groove 7 is fabricated on the transparent dielectric layer 3 by photolithography or etching.

[0053] Then, a refractive index adjustment layer 4 is prepared on the transparent dielectric layer 3.

[0054] Specifically, VO2 nanoparticles of phase change material are incorporated into PMMA photosensitive material to prepare a VO2-doped suspension as an electro-induced phase change material. A PMMA film doped with VO2 nanoparticles is formed on a transparent dielectric layer by photolithography, development and baking. The PMMA film is arranged into a Bragg grating, sampling grating, phase shift grating or equivalent phase shift grating pattern.

[0055] Subsequently, undoped PMMA material is spin-coated over a large area above the transparent dielectric layer 3 as a leveling layer 5 to fill the refractive index adjustment layer 4 and the optical waveguide groove 7.

[0056] Finally, metallic silver is prepared on top of fill layer 5 as... Figure 1 The top electrode layer 6 is shown.

[0057] When the wide-tunable filter waveguide is working, a voltage is applied to the top electrode layer 6 and the bottom electrode layer 2. The voltage changes the VO2 material from the dielectric phase to the metallic phase, which causes the overall refractive index of the VO2-doped PMMA hybrid material to change. This results in a significant change in the reflection or transmission spectrum of the Bragg grating, sampling grating, phase-shifting grating or equivalent phase-shifting grating, and produces a wide-tunable phenomenon along the light waveguide.

[0058] Example 2

[0059] The difference between the wide-tunable filter waveguide provided in Example 2 and Example 1 is that the substrate is a conductive substrate with a refractive index lower than that of the leveling material. The bottom electrode layer is fabricated at the bottom of the conductive substrate, and a transparent dielectric layer is fabricated at the top of the conductive substrate. The bottom electrode layer located below the conductive substrate is directly exposed, facilitating the application of current.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0062] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A wide-tunable filter waveguide, comprising an insulating substrate, wherein a bottom electrode layer and a transparent dielectric layer are sequentially fabricated on top of the insulating substrate, characterized in that, An optical waveguide groove is fabricated on the transparent dielectric layer. A refractive index adjustment layer is fabricated on the transparent dielectric layer in a direction perpendicular to the optical waveguide groove. A leveling material with a refractive index greater than that of the insulating substrate is used to level the refractive index adjustment layer and the optical waveguide groove, forming a leveling layer. A top electrode layer is fabricated on the leveling layer. The refractive index adjustment layer is an electro-phase change material or an electrochromic material. By changing the refractive index of the electro-phase change material or the electrochromic material, a wide tuning range of the filtered waveguide reflection spectrum or transmission spectrum is achieved. Under the influence of current or voltage, the volume and thickness of the electro-phase change material or the electrochromic material remain unchanged, but its properties change, and the real part of its refractive index changes.

2. The wide-tuned filter waveguide as described in claim 1, characterized in that, The electrochromic material is VO2, V2O5, germanium-antimony-tellurium, molybdenum telluride, or titanium-antimony-tellurium; the electrochromic material is tungsten oxide, molybdenum oxide, or nickel oxide; the refractive index adjustment layer is arranged to form a Bragg grating, a sampling grating, a phase-shifting grating, or an equivalent phase-shifting grating pattern.

3. A method for fabricating a wide-tunable filter waveguide as described in claim 1, characterized in that, Includes the following steps: S1. Prepare a bottom electrode layer on an insulating substrate; S2. A transparent dielectric layer is prepared on the bottom electrode layer; S3. Fabricate an optical waveguide groove on the transparent dielectric layer; S4. A refractive index adjustment layer is prepared on the transparent dielectric layer in a direction perpendicular to the optical waveguide groove; wherein, the refractive index adjustment layer is an electro-phase change material or an electrochromic material, and by changing the refractive index of the electro-phase change material or the electrochromic material, a wide tuning of the filtered waveguide reflection spectrum or transmission spectrum is achieved; the volume and thickness of the electro-phase change material or the electrochromic material remain unchanged under the action of current or voltage, but its properties change, and the real part of the refractive index changes; S5. A leveling material is used to fill the refractive index adjustment layer and the optical waveguide groove to form a leveling layer; S6. Prepare a top electrode layer on the filler layer.

4. The method for fabricating a wide-tuned filter waveguide as described in claim 3, characterized in that, The refractive index adjustment layer is prepared by vapor deposition or etching of the electro-phase change material or the electrochromic material, or by incorporating the electro-phase change material or the electrochromic material into a material with photosensitive properties and then preparing the refractive index adjustment layer by photolithography, development and baking.

5. The method for fabricating a wide-tuned filter waveguide as described in claim 4, characterized in that, VO2 nanoparticles are incorporated into PMMA to prepare a VO2-doped suspension as the electro-phase change material. A PMMA film doped with VO2 nanoparticles is formed on the transparent dielectric layer by photolithography, development and baking. The PMMA film is arranged into a Bragg grating, sampling grating, phase shift grating or equivalent phase shift grating pattern.

6. A wide-tunable filter waveguide, comprising a conductive substrate, a bottom electrode layer formed at the bottom of the conductive substrate, and a transparent dielectric layer formed at the top of the conductive substrate, characterized in that, An optical waveguide groove is etched on the transparent dielectric layer. A refractive index adjustment layer is fabricated on the transparent dielectric layer in a direction perpendicular to the optical waveguide groove. A leveling layer is formed by leveling the refractive index adjustment layer and the optical waveguide groove using a leveling material with a refractive index lower than that of the conductive substrate. A top electrode layer is fabricated on the leveling layer. The refractive index adjustment layer is an electro-phase change material or an electrochromic material. By changing the refractive index of the electro-phase change material or the electrochromic material, a wide tuning of the filtered waveguide reflection spectrum or transmission spectrum is achieved. Under the action of current or voltage, the volume and thickness of the electro-phase change material or the electrochromic material remain unchanged, but its properties change, and the real part of the refractive index changes.

7. The wide-tuned filtering waveguide as described in claim 6, characterized in that, The electrochromic material is VO2, V2O5, germanium-antimony-tellurium, molybdenum telluride, or titanium-antimony-tellurium; the electrochromic material is tungsten oxide, molybdenum oxide, or nickel oxide; the refractive index adjustment layer is arranged to form a Bragg grating, a sampling grating, a phase-shifting grating, or an equivalent phase-shifting grating pattern.

8. A method for fabricating a wide-tuned filter waveguide as described in claim 6, characterized in that, Includes the following steps: S1. Prepare a bottom electrode layer on the bottom of a conductive substrate; S2. A transparent dielectric layer is prepared on top of the conductive substrate; S3. Fabricate an optical waveguide groove on the transparent dielectric layer; S4. A refractive index adjustment layer is prepared on the transparent dielectric layer in a direction perpendicular to the optical waveguide groove; wherein, the refractive index adjustment layer is an electro-phase change material or an electrochromic material, and by changing the refractive index of the electro-phase change material or the electrochromic material, a wide tuning of the filtered waveguide reflection spectrum or transmission spectrum is achieved; the volume and thickness of the electro-phase change material or the electrochromic material remain unchanged under the action of current or voltage, but its properties change, and the real part of the refractive index changes; S5. A leveling material is used to fill the refractive index adjustment layer and the optical waveguide groove to form a leveling layer; S6. Prepare a top electrode layer on the filler layer.

9. The method for fabricating a wide-tuned filter waveguide as described in claim 8, characterized in that, The refractive index adjustment layer is prepared by vapor deposition or etching of the electro-phase change material or the electrochromic material, or by incorporating the electro-phase change material or the electrochromic material into a material with photosensitive properties and then preparing the refractive index adjustment layer by photolithography, development and baking.

10. The method for fabricating a wide-tuned filter waveguide as described in claim 9, characterized in that, VO2 nanoparticles are incorporated into PMMA to prepare a VO2-doped suspension as the electro-phase change material. A PMMA film doped with VO2 nanoparticles is formed on the transparent dielectric layer by photolithography, development and baking. The PMMA film is arranged into a Bragg grating, sampling grating, phase shift grating or equivalent phase shift grating pattern.

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