Method for producing an optical waveguide
The method of forming ZnO nanostructures via laser pulses and hydrothermal processes addresses the complexity and cost issues of existing lithography techniques, enabling efficient and cost-effective production of grating waveguides with diverse materials and morphologies.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- FOTONTEK OPTIK HABERLESME SISTEMLERI LTD SIRKETI
- Filing Date
- 2025-10-27
- Publication Date
- 2026-05-15
AI Technical Summary
Existing production techniques for grating waveguides, such as photolithography, electron beam lithography, and nanoimprint lithography, are complex and expensive, limiting the material diversity and efficiency of grating waveguide production.
A method involving laser pulses and hydrothermal processes is used to form ZnO nanostructured thin films on a glass substrate, eliminating the need for lithography and enabling the production of metal oxide grating patterns with varying refractive indices and morphologies, using economical materials like ZnO microwires and planar metal oxide structures.
Enables high-performance grating waveguide production with material diversity and reduced production costs, utilizing ZnO nanostructures formed at low temperatures.
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Abstract
Description
[0001] DESCRIPTION
[0002] METHOD FOR PRODUCING AN OPTICAL WAVEGUIDE
[0003] Technical Field of the Invention
[0004] The invention relates to a method for producing a grating-type optical waveguide.
[0005] State of the Art
[0006] Grating waveguides are thin films produced in a grating pattern at controlled intervals and in a regular arrangement. By means of these structures, electromagnetic waves propagate while being diffracted at a specific angle.
[0007] Grating waveguides comprise a core layer and a cladding layer. Electromagnetic waves propagate within the core layer and interact with the cladding layer. The refractive index of the cladding layer must be lower than that of the core layer.
[0008] They offer advantages such as directing the waves with high efficiency and reducing signal losses.
[0009] However, complex and expensive production techniques such as photolithography, electron beam lithography (EBL), and nanoimprint lithography are used.
[0010] As a result, all the problems mentioned above have made it necessary to make an innovation in the relevant field.
[0011] The Aims and Brief Description of the Invention
[0012] The main aim of the invention is to contribute to the development of high-performance grating waveguide studies by enabling the production of all kinds of metal oxide grating patterns with differences in refractive index and elevation through this method, thereby providing material diversity.
[0013] Since the grating patterns are formed by laser pulses, lithography methods are eliminated. ZnO nanostructured thin film can be produced at low temperature with economical starting materials.
[0014] ZnO nanostructure can be produced in different morphologies such as 1 D and 3D by varying factors such as the types of starting materials, reaction environment temperature, and pH level.
[0015] Detailed Description of the Figures
[0016] The figures and related explanations used in order to better explain the device developed with this invention are given below.
[0017] Figure 1 . Flow chart of the production method of the invention.
[0018] Detailed Description of the Invention
[0019] The invention covers a production method of a waveguide device comprising 1 D microstructured metal oxide microwires and planar metal oxide paired structures formed on a glass substrate, obtained by growing the 1 D metal oxide microwires by means of a hydrothermal method. The method is completed in several different stages, and each stage is applied meticulously in order to form the microstructure of the waveguide device.
[0020] In the first stage, a glass substrate is prepared. Said substrate serves as a base for the growth of the 1 D metal oxide microwire thin film layer. As described in claim 2, the glass substrate is preferably silica glass. Silica glass is a commonly used material due to its thermal resistance and optical properties, and provides an ideal surface for waveguides.
[0021] In the next step, a thin film layer of the relevant metal oxide required for the growth of the 1 D metal oxide microwire is formed on the glass substrate. This process is carried out by means of the radio frequency (RF) magnetron sputtering method using the target material of the relevant metal oxide. The sputtering process is performed under a pressure of 7.6 x 1 O-6Torr in an argon gas atmosphere of 99.999% purity. At this stage, a ZnO thin film layer is grown for 9-15 minutes using a power of 60 W. For titanium (Ti) metal, coating is performed at 100 W for 30 minutes, followed by calcination at 550°C for 2 hours. This thin film layer then serves as a seed layer for the growth of the microwires.
[0022] A metal layer is deposited on the ZnO layer by means of the radio frequency magnetron sputtering method. This metal is preferably selected as aluminium (Al). Alternatively, copper (Cu) or titanium (Ti) may also be used. At this stage, a power of 100 W is used, and the process is carried out for 10-30 minutes under the same environmental conditions.
[0023] In the third stage, laser energy is applied onto the coated aluminium layer. As the laser source, a nanosecond or femtosecond laser may be used. The power of the nanosecond laser is adjusted in the range of 10-25 W, and laser pulses are applied in predetermined regions. In the same process, for the femtosecond laser, the power is adjusted in the range of 4-10 mW, and laser pulses are applied in predetermined regions. This process allows ZnO to be exposed in the regions contacted by the laser and prepares the ground for the growth of microwires in these regions. In the regions not contacted by the laser, the Al layer remains, which contributes to the sensitive structures of the device.
[0024] A hydrothermal process is applied to the ZnO regions exposed by the laser to grow the microwires. This process is carried out with a 0.1 M solution of the Zn(NO3)26H2O compound prepared in deionised water. Additionally, 2% by weight (v / v) ammonium hydroxide (or NaOH) is added to the solution. The hydrothermal reaction is carried out at 80°C for 1 hour. This process ensures that the ZnO microwires possess the desired structural properties.
[0025] In the final step, the produced substrates are calcined at 300°C for 2 hours. The calcination process ensures the formation of planar metal oxide (AI2O3, TiO2, Cu2O) and ZnO microwire phases. This process enhances the stability of the material and optimises the performance of the waveguide device.
Claims
CLAIMS1. A method for producing a waveguide device, comprising the following process steps of:• a glass substrate,• forming a metal oxide thin film layer in an argon gas atmosphere with a purity of 99.990%-99.999%, under a pressure of 7.6 x 1 O’6Torr, using a metal oxide target material with a purity of 99.990%-99.999%, by means of a radio frequency magnetron sputtering method applied for 12 to 20 minutes at a power range of 60 W to 100 W, in order to increase the adhesion ability of the metal oxide microstructure to the surface of the glass substrate;• a metal layer obtained by coating the metal oxide layer with a metal through a radio frequency magnetron sputtering method at a power of 150 W to 300 W for 10 to 30 minutes under the same environmental conditions;• performing laser pulses with a laser device on the metal layer in such a way that the metal oxide is exposed in the regions contacted by the laser, and the metal layer remains in the regions not contacted by the laser;• a hydrothermal reaction for the growth of metal oxide microwires in the regions exposed by the laser, with a 0.1 M solution of the metal oxide salt prepared in deionised water, carried out at a temperature of 80°C to 200°C for a duration of 1 to 12 hours; and• calcining the coated substrates at temperatures between 300°C and 600°C for 2 to 4 hours in order to form metal, metal oxide, and metal oxide microwire phases.
2. A method for producing a waveguide device according to claim 1 , wherein the glass substrate is silica glass.
3. A method for producing a waveguide device according to claim 1 , wherein said metal oxide is ZnO.
4. A method for producing a waveguide device according to claim 1 , wherein said metal is aluminium (Al).
5. A method for producing a waveguide device according to claims 1 and 3, wherein, when said metal oxide is selected as ZnO for forming the metal oxide thin film layer, the radio frequency magnetron sputtering method is carried out at a power of 60 W for 12 minutes.
6. A method for producing a waveguide device according to claims 1 and 4, wherein, when said metal is selected as Al for forming the metal layer, the radio frequency magnetron sputtering method is carried out at a power of 150 W for 12 minutes.
7. A method for producing a waveguide device according to claim 1 , wherein the laser device is a nanosecond laser device.
8. A method for producing a waveguide device according to claim 7, wherein the energy of said nanosecond laser device is adjusted in the range of 10 W to 25 W.
9. A method for producing a waveguide device according to claim 1 , wherein the laser device is a femtosecond laser device.
10. A method for producing a waveguide device according to claim 9, wherein the energy of said femtosecond laser device is adjusted in the range of 4 mW to 10 mW.
11. A method for producing a waveguide device according to claims 1 and 3, wherein, when ZnO is used as the metal oxide, 2% by weight of ammonium hydroxide is added to the solution used in the hydrothermal reaction step.
12. A method for producing a waveguide device according to claims 1 and 3, wherein the metal oxide salt used in the hydrothermal reaction is Zn(NO3)26H2O.
13. A method for producing a waveguide device according to claims 1 , 3, and 4, wherein, when the metal oxide is ZnO and the metal is Al, the calcination step is carried out at 300°C for 2 hours.