A side-emitting quartz optical fiber

Abstract

The present invention relates to a side-emitting quartz optical fiber, comprising a core layer and a cladding covering the core layer, wherein the cladding is coated with a resin coating layer. The optical fiber is characterized in that the radius R1 of the core layer is 25 to 40 μm, the relative refractive index difference Δn1 is 0 to 0.3%, the radius R2 of the cladding is 60 to 90 μm, the relative refractive index difference Δn2 is -0.1% to -0.03%, the cladding contains bubbles with a radius of 100 to 400 nm as light scatterers, the outermost layer of the optical fiber is a resin coating layer, the radius R3 of the resin coating layer is 120 to 150 nm, the relative refractive index difference Δn3 is -3% to -6%, and the resin coating layer contains inorganic oxide particles with a radius of 50 to 150 nm. The present invention utilizes a chemical vapor deposition process to deposit a preform rod, which can control the formation of bubbles in the core layer and the cladding, thereby causing scattering. The scattered light intensity is forward-concentrated, i.e., scattered toward the outer surface, forming side-luminescence. The addition of inorganic oxide scattering particles in the resin coating layer can scatter the guided light, making the optical fiber emit light more uniformly and having better light quality.

Description

Technical Field

[0001] The invention relates to a side-emitting quartz optical fiber, belonging to the technical field of light conduction. Background Art

[0002] Silica optical fiber utilizes the principle of total internal reflection to transmit light signals with minimal loss, making it widely used in optical communications. This type of communication fiber transmits light with virtually no light leakage from the cladding. Side-emitting optical fibers are also in demand in decorative, measurement, and medical applications. These fibers not only transmit light from the input end to the output end, but also allow some light to leak from the cladding, resulting in side-emitting light. Currently, most side-emitting optical fibers are plastic optical fibers. However, due to process and material limitations, the uniformity of light emission and the excessively large diameter of plastic optical fibers hinder their application and deployment. Summary of the Invention

[0003] The following are definitions and explanations of some terms used in this invention: Starting from the central axis of the optical fiber, based on the change in refractive index, the layer closest to the axis is defined as the core layer, the outer cladding layer surrounding the core layer is defined as the optical fiber cladding layer, and the outermost layer is defined as the coating resin layer. The relative refractive index difference Δni of each optical fiber layer is defined by the following equation:

[0004]

[0005] where n i is the absolute refractive index of a specific layer of the optical fiber, and n c is the refractive index of pure silicon dioxide. When light interacts with matter, a series of physical phenomena occur, including transmission, refraction, and scattering. Elastic scattering can be divided into Rayleigh scattering and Mie scattering, and its characteristics are related to parameters such as the wavelength of the incident wave and the size, density, and shape of the interacting particles. According to the relationship between the particle size and the wavelength of light, it can be determined whether it is Rayleigh scattering or Mie scattering. The ratio of the particle size to the wavelength is set to X, and the following formula is used as the judgment standard,

[0006]

[0007] Where r is the particle radius; λ is the wavelength; when X < 1, it can be determined as Rayleigh scattering; when X ≥ 1, it can be determined as Mie scattering. Rayleigh scattering means that when light hits a particle whose diameter is much smaller than the wavelength of light, the light will scatter in all directions, and the shorter the wavelength of light, the greater the scattering intensity, and the scattering intensity is inversely proportional to the fourth power of the wavelength:

[0008]

[0009] Mie scattering refers to the phenomenon in which light is scattered primarily in the direction of its original travel when it strikes particles with a diameter comparable to or larger than the wavelength of the light. Mie scattering is stronger in the forward direction than in the backward direction, and its directionality is more pronounced. When the particle size is close to the wavelength, there is a phenomenon of resonance-enhanced scattering. When dealing with the scattering of spherical particles under light irradiation, a dimensionless particle size parameter is usually introduced, namely:

[0010]

[0011] Where D is the particle diameter, m1 is the refractive index around the scattering particle, and λ is the wavelength. When α increases, the scattered light intensity tends to be forward concentrated.

[0012] The technical problem to be solved by the present invention is to provide a side-emitting quartz optical fiber with uniform light emission, thin diameter and controllable manufacturing process in response to the above-mentioned deficiencies in the prior art.

[0013] The technical solution adopted by the present invention to solve the above-mentioned problems is: it includes a core layer and a cladding covering the core layer, and the cladding is covered with a resin coating layer. It is characterized in that the core layer radius R1 is 25 to 40 μm, the relative refractive index difference Δn1 is 0 to 0.3%, the cladding radius R2 is 60 to 90 μm, the relative refractive index difference Δn2 is -0.1% to -0.03%, the cladding contains bubbles with a radius of 100 to 400 nm as light scatterers, the outermost layer structure of the optical fiber is a resin coating layer, the resin coating layer radius R3 is 120 to 150 nm, the relative refractive index difference Δn3 is -3% to -6%, and the resin coating layer contains inorganic oxide particles with a radius of 50 to 150 nm.

[0014] According to the above solution, the bubble filling rate (duty ratio) in the cladding is 10% to 20%.

[0015] According to the above solution, the core layer contains bubbles with a radius of 100 to 200 nm, and the bubble filling rate (duty cycle) is 5% to 10%.

[0016] According to the above scheme, the bubbles contain one or more gases, and the gases are argon, nitrogen, and oxygen.

[0017] According to the above solution, the core layer is a germanium-doped silica glass layer, or a pure silica glass layer, and the cladding layer is a fluorine-doped silica glass layer.

[0018] According to the above solution, the resin layer material is based on acrylic esters, and the base material is mixed with inorganic oxide particles in a weight ratio of 1 to 35%.

[0019] According to the above solution, the inorganic oxide particles are one or more of titanium dioxide, zirconium dioxide, titanium oxide, tin oxide and zinc oxide.

[0020] According to the above solution, the difference between the radius of the cladding layer and the core layer is R2-R1≥30μm.

[0021] According to the above solution, the numerical aperture of the optical fiber is 0.3 to 0.6.

[0022] According to the above solution, the optical fiber is formed by melting and drawing an optical fiber preform rod, and the optical fiber preform rod is formed by chemical vapor deposition.

[0023] The beneficial effects of the present invention are as follows: 1. The wavelength range of the light source used in the optical fiber of the present invention is 390nm to 780nm visible light, and the preform rod is deposited by the chemical vapor phase process, which can control the formation of bubbles in the core layer and cladding to form scattering. The bubble size is 100nm to 400nm, that is, Mie scattering occurs, and the particle diameter is equivalent to the wavelength, which will lead to enhanced scattering. The scattered light intensity is forward-concentrated, that is, scattered toward the outer surface, forming side emission; 2. The addition of inorganic oxide scattering particles in the resin coating layer can scatter the guided light, making the optical fiber emit light more uniformly and the light quality better; 3. The core and cladding structure is simple, the chemical vapor phase process can be used to achieve bubble generation, and the diameter of the optical fiber can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 FIG. 1 is a schematic diagram of a cross-sectional view of the refractive index of an optical fiber according to an embodiment of the present invention.

[0025] Figure 2 Schematic diagram of a radial cross-section of an optical fiber according to an embodiment of the present invention.

[0026] Figure 3 This is the attenuation curve of an embodiment of the present invention at a wavelength of 300nm to 800nm.

[0027] Figure 4 This is a measured optical power attenuation curve of an embodiment of the present invention.

[0028] Figure 5 This is a picture of an embodiment of the present invention showing red light on the side.

[0029] Figure 6 This is a picture of an embodiment of the present invention showing green light emitted from the side. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0031] The optical fiber comprises a core layer 01 and a cladding layer 02 surrounding the core layer. The cladding layer is coated with a resin coating layer 03. The core layer has a radius of R1 and a relative refractive index difference of Δn1. The cladding has a radius of R2 and a relative refractive index difference of Δn2. The cladding layer contains bubbles with a radius of 100 to 400 nm as light scatterers. The outermost layer of the optical fiber is a resin coating layer with a radius of R3 and a relative refractive index difference of Δn3. The resin coating layer contains inorganic oxide particles with a radius of 50 to 150 nm. The core layer is a germanium-doped silica glass layer or a pure silica glass layer. The core layer may contain multiple bubbles 06 with a radius of 100 to 200 nm and a bubble filling rate (duty cycle) of 5% to 10%. The bubbles contain one or more gases, such as argon, nitrogen, or oxygen. The presence of these bubbles reduces the equivalent average refractive index of the entire core layer region. The cladding is a fluorine-doped silica glass layer containing a plurality of bubbles 05, each with a radius of 100 to 400 nm and a bubble filling ratio (duty cycle) of 10% to 20%. The bubbles contain one or more gases, such as argon, nitrogen, or oxygen. The presence of these bubbles reduces the equivalent average refractive index of the entire cladding region. In some embodiments, the optical fiber has a numerical aperture greater than 0.3, preferably greater than 0.4, and more preferably 0.6. The specific manufacturing process of the present invention is as follows: a preform rod having a core layer and a cladding is formed by chemical vapor deposition. During sintering, the preform rod passes through a heating zone at a speed of 10 mm / min, the sintering temperature is 1700°C, and the sintering gas is 100% nitrogen, forming a bubble-free core area + a bubble-containing cladding, or a bubble-containing core area + a bubble-containing cladding; during the optical fiber drawing process, the drawing tension is 100-200 g, and a low-refractive index resin coating layer is used. The resin coating layer contains inorganic oxide particles 04 as a light scatterer, so that the light leaked from the side-emitting optical fiber can be more evenly scattered out of the outer surface of the optical fiber. The inorganic oxide is titanium dioxide, zirconium dioxide, titanium oxide, tin oxide, and zinc oxide, preferably titanium dioxide, and the particle radius is 50 to 150 nm. Figure 3 This is the attenuation spectrum of an embodiment of the present invention tested in the range of 300nm to 800nm. In the visible light wavelength range, the attenuation is greater than 50dB / km and less than 400dB / km. Figure 5 In some embodiments, a 650 nm red laser is connected to the end face of the optical fiber, and the red light is scattered from the side of the optical fiber. Figure 6 In some embodiments, a 532 nm green laser is connected to the end face of the optical fiber, and the green light is scattered from the side of the optical fiber. Table 1 is a parameter table of some embodiments of the present invention.

[0032] Table 1:

[0033]

[0034] By modifying the refractive index profile, forming bubbles, and adding scattering particles to the coating resin layer, quartz-based side-emitting optical fibers can be created to produce uniform, controllable side-emitting optical fibers. These fibers are primarily used for automotive door panel and interior ambient lighting, with potential applications in the medical and biological industries, such as photobiostimulation and laser acupuncture, non-invasive subcutaneous vascular irradiation therapy or bioactive therapies, and in medical devices for both linear and planar illumination, such as for microscopic biological specimen illumination.

Claims

1. A side-emitting quartz optical fiber comprising a core layer and a cladding layer covering the core layer, wherein the cladding layer is covered with a resin coating layer, characterized in that The core layer radius R1 is 25~40μm, the relative refractive index difference Δn1 is 0~0.3%, the cladding radius R2 is 60~90μm, the relative refractive index difference Δn2 is -0.1%~-0.03%, the cladding contains bubbles with a radius of 100~400nm as light scatterers, the outermost layer structure of the optical fiber is a resin coating layer, the resin coating layer radius R3 is 120~150nm, the relative refractive index difference Δn3 is -3%~-6%, and the resin coating layer contains inorganic oxide particles with a radius of 50~150nm; the numerical aperture of the optical fiber is 0.3~0.

6.

2. The side-emitting silica optical fiber according to claim 1, characterized in that The bubble filling rate in the cladding is 10% to 20%.

3. The side-emitting silica optical fiber according to claim 2, characterized in that The core layer contains bubbles with a radius of 100-200 nm, and the bubble filling rate is 5%-10%.

4. The side-emitting silica optical fiber according to claim 2 or 3, characterized in that The bubbles contain one or more gases, and the gases are argon, nitrogen, and oxygen.

5. The side-emitting silica optical fiber according to claim 1 or 2, characterized in that The core layer is a germanium-doped silica glass layer, or a pure silica glass layer, and the cladding layer is a fluorine-doped silica glass layer.

6. The side-emitting silica optical fiber according to claim 1 or 2, characterized in that The resin coating layer material is based on acrylic esters, and the base material is mixed with inorganic oxide particles in a weight ratio of 1 to 35%.

7. The side-emitting silica optical fiber according to claim 6, characterized in that The inorganic oxide particles are one or more of titanium dioxide, zirconium dioxide, titanium oxide, tin oxide and zinc oxide.

8. The side-emitting silica optical fiber according to claim 1 or 2, characterized in that The difference between the radius of the cladding layer and the core layer is R2-R1≥30μm.

9. The side-emitting silica optical fiber according to claim 1 or 2, characterized in that The optical fiber is formed by melting and drawing an optical fiber preform rod, and the optical fiber preform rod is formed by chemical vapor deposition.

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