EP4732052A1

EP4732052A1 - Poly(dimethylsiloxane) (pdms)-nano cellulose crystal (ncc)-based flexible optical waveguide and power splitter device

Info

Publication number: EP4732052A1
Application number: EP24927658.5A
Authority: EP
Inventors: Mediha TUTGUN; Çigdem TUÇ ALTAF; Ahmet Arif VARSAK; Zeynep EVIRGEN AKYÜZ; Ahmet KARATAY; Elif YILDIZ
Original assignee: Fotonek Optik Haberlesme Sistemleri Ltd Sirketi
Current assignee: Fotonek Optik Haberlesme Sistemleri Ltd Sirketi
Priority date: 2024-09-12
Filing date: 2024-10-11
Publication date: 2026-04-29
Also published as: TR2024012130A1; WO2026059506A1

Abstract

The invention relates to a multi-mode fibre optic power splitter comprising polymer material and nanoscale reinforcement.

Description

DESCRIPTION

POLY(DIMETHYLSILOXANE) (PDMS)-NANO CELLULOSE CRYSTAL (NCC)- BASED FLEXIBLE OPTICAL WAVEGUIDE AND POWER SPLITTER DEVICE

Technical Field of the Invention

State of the Art

Traditional glass fibres are brittle and have low bending and tensile strength. In addition, polymer-based optical waveguides have problems such as moisture absorption, high losses and high cost. Silicon-based polymers are brittle, sensitive to UV light and show deterioration throughout their life. Therefore, flexible, durable and cost-effective optical waveguides and power splitters are needed.

As a result, all the problems mentioned above have made it necessary to make an innovation in the relevant field.

The Aims and Brief Description of the Invention

The main aim of the invention is to develop flexible optical waveguides and power splitter devices using a composite material containing PDMS and nano cellulose crystal (NCC). PDMS offers excellent optical transparency, low weight, flexibility and chemical resistance, while NCC provides thermal and mechanical reinforcement and allows better guidance of light. By using this composite material as a core and cladding material, desired refractive index differences can be achieved.

Detailed Description of the Figures

The figures and related explanations used in order to better explain the device developed with this invention are given below.

Figure 1. Isometric view of the multi-mode fibre optic waveguide that is the subject of the invention Figure 2. Isometric view of the multi-mode fibre optic power splitter that is the subject of the invention

Figure 3. Refractive index change according to NCC amount

Definition of Elements/ZParts Composing the Invention

In order to better explain the device developed with this invention, the parts and pieces in the figures are numbered, and the equivalent of each number is given below.

1. Multi-mode fibre optic device

2. Cladding

3. Core

4. Cable

5. Cover

Detailed Description of the Invention

The present invention relates to the development of multi-mode fibre optic waveguides and multi-mode fibre optic power splitters using a flexible composite material. Conventional optical waveguides are generally made of glass or rigid polymers, which lack flexibility and may suffer from mechanical strength problems. Moreover, the limited adjustability of the refractive index properties of these materials may limit the performance of the waveguides. The present invention discloses a product made of a flexible composite material formed using Poly(dimethylsiloxane) (PDMS) and nano cellulose crystal (NCC) to overcome such limitations.

The invention describes a multi-mode fibre optic device (1 ). The device has a cable (4) structure and includes a core (3) positioned to receive a portion of the cable. The core is made of Polydimethylsiloxane (PDMS). The cladding material has a certain minimum thickness to provide the desired refractive index difference between the core and the cladding (2). The cladding material consists of PDMS and nano-cellulose crystal (NCC) which is a sustainable nano-scale reinforcement material. This cladding makes the device flexible and water resistant. In addition, the device has high temperature resistance. The invention preferably comprises a cover (5) that will enclose the entire system.

PDMS is a silicone-based elastomer and has a wide range of use in optical applications. This material is known for its excellent optical transparency, low weight, flexibility, chemical resistance and low attenuation properties. Another important advantage of PDMS is that the refractive index can be adjusted by changing parameters such as curing temperature, base/curing agent ratio and additives added. This feature makes PDMS a preferred material in optoelectronic applications such as waveguides and optical splitter devices.

However, the use of PDMS alone can lead to deterioration, especially when exposed to UV light for long periods. This causes the matrix structure of PDMS to attenuate over time and may lead to a decrease in optical performance. To overcome this problem, in our invention, the PDMS matrix is reinforced with nano cellulose crystal (NCC). NCC is a natural nanomaterial derived from cellulose and is known for its fibre structure consisting of long glucose chains. These fibres are tightly packed and usually found in bundles, increasing the mechanical strength of the material.

Integrating NCC into the PDMS matrix significantly increases the thermal stability of the composite material. The increased thermal stability enables the device to operate in a wide temperature range and to be durable even in harsh environmental conditions. Another important feature of NCC is its refractive index value of approximately 1 .492. This high refractive index value makes it possible to achieve the desired refractive index difference between the core and cladding materials by adjusting the ratio of PDMS to NCC. This difference enables the efficient guidance of light along the waveguide and optimises the optical performance.

Combining PDMS and NCC as a composite material increases mechanical strength as well as flexibility. While traditional glass fibre optic waveguides face problems such as brittleness and cracking, the PDMS-NCC composite is resistant to such mechanical weaknesses. This makes the composite material ideal for use in mobile systems, such as automobiles and wearable devices. These devices are an excellent solution for applications where the waveguide must be flexible.

The crystalline structure of cellulose and the irregularities it contains tend to scatter light. This feature makes cellulose ideal for use as an optical cladding material, because the cellulose used as the cladding material scatters light that does not pass through the core of the waveguide, providing efficient optical isolation. Thicker layers of cellulose result in less light being transmitted, which can be used to control the light transmission of the waveguide.

The invention also offers an environmentally friendly solution. NCC is a natural, biodegradable material since it is derived from cellulose. When combined with PDMS, a biocompatible composite material is obtained. This is particularly important for applications such as medical devices where compatibility with biological systems is required. In addition, both PDMS and NCC are recyclable materials, making them suitable for sustainable production of optical devices.

It provides a flexible and durable composite material consisting of a combination of PDMS and NCC. This material is ideal for multi-mode fibre optic devices (1 ) and combines optical performance, mechanical durability and environmental sustainability. The applicability of the invention offers a wide range of industrial and commercial applications. Great advantages are achieved especially in areas where flexibility and durability are important, such as mobile systems, wearable technologies and biocompatible devices.

Other prominent advantages of this invention include high optical transmittance, light weight, thermal and mechanical stability, recyclability and reusability. These features make this invention superior to the systems in the state of the art and have a wide potential for use in industrial applications.

This invention develops flexible optical waveguide and power splitter devices using a composite material consisting of PDMS and nano cellulose crystal (NCC). PDMS offers excellent optical transparency, low weight, flexibility and chemical resistance, while NCC provides thermal and mechanical reinforcement and allows better guidance of light. By using this composite material as the core (3) and the cladding (2) material, the desired refractive index differences can be achieved.

The combination of PDMS and NCC provides superior performance in both optical properties and mechanical durability, offering significant advantages over traditional glass fibres and other polymer-based systems. This invention may set a new standard for flexible optical waveguides and power splitters.

This invention offers an innovative solution to these technical problems by using PDMS and nano cellulose crystal (NCC) composite material. PDMS is a polymer widely used in optical components due to its flexibility, chemical resistance and excellent optical transparency. However, when used alone, it can be sensitive to UV light and its mechanical strength may be limited. Nano cellulose crystal (NCC), on the other hand, offers strong mechanical properties and thermal resistance and plays an important role in guiding light. Combining NCC with PDMS combines the advantages of these two materials, making it possible to produce high-performance, flexible and durable optical waveguides and power splitters.

With reference to Figure-3, the composite material used in the invention is obtained by combining PDMS and NCC in certain proportions. This composite is used as a core and cladding material, providing the desired refractive index differences in optical waveguides. The composite material is prepared with the proportions that 1.5% to 3.0% by weight of the mixture will be NCC and the rest will be PDMS.

The refractive index of PDMS (r[=1 .41 ) can be adjusted depending on the material ratios used, curing temperature and additives. In the study, the refractive index obtained when the PDMS elastomer: curing agent ratio was 7:1 was determined as 1 .431 . By adding NCC (r[= 1 .46), which has a higher refractive index, at low ratios, the refractive index of the composite material can be increased, allowing the light to be guided more effectively. The composite material used in this invention offers high optical transmittance and low losses. This provides a great advantage especially in optical systems requiring light manipulation and signal transmission.

Combining NCC with PDMS significantly increases the mechanical strength of the composite material. In this way, flexible optical components become resistant to physical stresses such as bending and stretching.

It provides a flexible and durable composite material consisting of a combination of PDMS and NCC. This material is ideal for optical waveguides and splitter devices and combines optical performance, mechanical durability and environmental sustainability. The applicability of the invention offers a wide range of industrial and commercial uses. It provides great advantages especially in areas where flexibility and durability are important such as mobile systems, wearable technologies and biocompatible devices.

Other prominent advantages of this invention include high optical transmittance, light weight, thermal and mechanical stability, recyclability and reusability. These features are the elements that make this invention superior to systems in the state of the art and offer a wide range of use potential in industrial applications.

As a result, the invention mentioned above, unlike the state of the art, describes a structure that is resistant to water and heat and more robust and flexible than prior art systems in terms of durability.

With reference to Figure-1 , in one embodiment of the invention, the cable (4) structure with a single input and single output allows the multi-mode fibre optic device (1 ), the features of which are mentioned above, to be defined as a multi-mode fibre optic waveguide.

With reference to Figure-2, in another embodiment of the invention, the cable (4) structure with a single input and two output structures also allows the multi-mode fibre optic device (1 ) the features of which are mentioned above to be defined as a multimode fibre optic power splitter.

Claims

1. A multi-mode fibre optic device (1 ), comprising

• A cable (4) structure,

• A core (3)

That is Positioned to contain a portion of the said cable (4) structure, and Is made of polydimethylsiloxane (PDMS) material,

• a cladding (2)

That has a minimum thickness of 0.4 mm to obtain the desired refractive index difference between itself and the core (3), and comprises

In the composite selected as material,

1.5%-3% by weight of nano-cellulose crystals (NCC), which is also a sustainable material as a nano-scale reinforcement, making it flexible and insoluble in water, and

Polydimethylsiloxane (PDMS) enough to complete the remaining amount according to the NCC ratio by weight.

2. A multi-mode fibre optic device (1 ) according to Claim 1 , comprising said cable structure that has at least one input and at least one output.

3. A multi-mode fibre optic device (1 ) according to Claim 1 , comprising said cables (4) selected as fibre optic cables.

4. A multi-mode fibre optic device (1 ) according to Claim 1 , comprising, in said cladding (2), NCC with a refractive index value between 1.4 and 1 .5 depending on the amount of NCC.

5. A multi-mode fibre optic device (1 ) according to Claim 1 , comprising an NCC derived from cellulose, a natural material in which long glucose chains are linked together in a linear arrangement.

6. A multi-mode fibre optic device (1 ) according to Claim 5, comprising cellulose fibres that are tightly packed and bundled together and whose irregularities and crystalline structure scatter light, reducing the amount of light that passes directly through the material.

7. A multi-mode fibre optic device (1 ) according to Claim 1 , comprising, in said core (3), a maximum of 3% by weight of NCC in addition to the PDMS material.