Plastic optical fibre and optical fibre transmission system

Abstract

A plastic optical fibre and an optical fibre transmission system are provided. The plastic optical fibre comprises a fibre core (110) and a cladding layer (120); the cladding layer circumferentially wraps the fibre core, and the fibre core and the cladding layer are both made of a non-PFAS plastic material. The present application further provides an optical fibre transmission system, which is used for a vehicle lamp lighting system.

Description

Plastic optical fibre and optical fibre transmission system

[0001] Embodiments of the present disclosure generally relate to the field of optical fibres, and more specifically relate to non-PFAS (Per- & Polyfluoroalkyl Substances) plastic optical fibres, and an optical fibre transmission system that is equipped with such a plastic optical fibre.

[0002] A plastic optical fibre is a light-guiding fibre and is made of a highly transparent plastic material. Due to their light weight, flexibility, resistance to damage, strong guiding capability, low cost, freedom from radiation, and being unaffected by electromagnetic and radio frequency interference and noise, plastic optical fibres have broad applications in multiple fields that involve communications, the automobile industry, industrial control, consumer electronics, home networks and smart homes, medical devices, lighting, etc.

[0003] Generally, plastic optical fibres mainly comprise a fibre core and a cladding layer, the fibre core being used for guiding the propagation of light therein, and the cladding layer having a lower refractive index than the fibre core, to reflect and refract light propagating in the fibre core, and fluoropolymer materials generally have a comparatively lower refractive index, and accordingly are one of the most common materials for the cladding layer in conventional plastic optical fibres.

[0004] However, fluoropolymers are PFAS materials, and PFAS materials are known as “persistent organic pollutants (POPs)” because they take hundreds of years to degrade in soil and water; PFAS also easily migrate in the environment, and, when a person or animal ingests PFAS, the PFAS accumulates in the organism and produces toxins, which affect the immune system and the reproductive system, interfere with the endocrine system, and have the potential to cause cancer, these being the known risks of PFAS. Therefore, in recent years, with more thorough research, the health risks of PFAS have increasingly drawn the attention of various countries, and countries and regions across the world are all expediting the formulation of relevant laws and policies, to strengthen control of PFAS. Therefore, to satisfy requirements of PFAS laws and policies of relevant countries or regions, and eliminate PFAS risks, it is necessary to reduce or prevent the use of PFAS materials, such as fluoropolymers, in plastic optical fibres.Summary of the Invention

[0005] An objective of the present disclosure is to solve or overcome at least one of the above and other problems and shortcomings in the prior art.

[0006] According to one aspect of the present disclosure, a plastic optical fibre is provided, which comprises a fibre core and a cladding layer, the cladding layer circumferentially wrapping the fibre core, and the fibre core and the cladding layer both being made of a non-PFAS plastic material.

[0007] In some embodiments, the cladding layer is made of a non-fluoropolymer material.

[0008] In some embodiments, a refractive index of the fibre core is greater than a refractive index of the cladding layer, and a difference in refractive index between the fibre core and the cladding layer is greater than or equal to 0.04.

[0009] In some embodiments, a difference in refractive index between the fibre core and the cladding layer is greater than or equal to 0.1.

[0010] In some embodiments, the material of the fibre core comprises polymethyl methacrylate (PMMA), an acrylic block copolymer, polyurethane (PU) or acrylate polymer.

[0011] In some embodiments, the material of the cladding layer is a silicone rubber (SR) or poly 4-methyl-1-pentane (TPX) material.

[0012] In some embodiments, the cladding layer is a silicone rubber layer.

[0013] In some embodiments, the plastic optical fibre further comprises a sub-fibre core layer, and the sub-fibre core layer wraps an outer peripheral surface of the fibre core and is located between the fibre core and the cladding layer.

[0014] In some embodiments, the sub-fibre core layer is formed by a transparent material with a refractive index greater than or equal to the refractive index of the fibre core and greater than the refractive index of the cladding layer.

[0015] In some embodiments, the sub-fibre core layer is formed by a transparent material with a refractive index slightly less than the refractive index of the fibre core and greater than the refractive index of the cladding layer.

[0016] In some embodiments, a crosslinking bonding capability between the sub-fibre core layer and the cladding layer is greater than a crosslinking bonding capability between the fibre core and the cladding layer.

[0017] In some embodiments, the material of the sub-fibre core layer comprises a polymethyl methacrylate (PMMA) or thermoplastic elastomer material.

[0018] In some embodiments, the cladding layer is cured on an outer peripheral surface of the sub-fibre core layer.

[0019] In some embodiments, the plastic optical fibre further comprises a transparent emergent light layer and a reflective layer, wherein the transparent emergent light layer covers an outer peripheral face of the cladding layer, configured to cast light from the cladding layer, and the reflective layer is at least partially opposite an emergent light region, to reflect light from the transparent emergent light layer toward the emergent light region.

[0020] In some embodiments, the transparent emergent light layer is formed of a material that does not contain fluorine.

[0021] According to another aspect of the present disclosure, an embodiment further provides an optical fibre transmission system, comprising a light source assembly having a light source and the plastic optical fibre described in any of the embodiments of the present disclosure, and one end of the plastic optical fibre is coupled to the light source assembly, to receive and propagate light from the light source.

[0022] In some embodiments, the optical fibre transmission system is a vehicle lamp lighting system.

[0023] A detailed description of the present disclosure is provided below with reference to the accompanying drawings to make other objectives and advantages of the present disclosure apparent and help achieve a comprehensive understanding of the present disclosure.Brief Description of the Drawings

[0024] These and / or other aspects, features and advantages of the present disclosure will become apparent and readily understood from the following description of some illustrative embodiments in conjunction with the accompanying drawings. In the drawings:

[0025] is a perspective drawing schematically showing the structure of an optical fibre transmission system according to an exemplary embodiment of the present disclosure;

[0026] is a cutaway view schematically showing the structure of an optical fibre transmission system according to an exemplary embodiment of the present disclosure;

[0027] is a schematic drawing showing a plastic optical fibre according to an exemplary embodiment of the present disclosure;

[0028] is a sectional drawing showing the structure of a plastic optical fibre according to an exemplary embodiment of the present disclosure;

[0029] is an end view showing the structure of a plastic optical fibre according to an exemplary embodiment of the present disclosure;

[0030] is a sectional drawing showing the structure of a plastic optical fibre according to another exemplary embodiment of the present disclosure;

[0031] is an end view showing the structure of a plastic optical fibre according to another exemplary embodiment of the present disclosure;

[0032] is a sectional drawing showing the structure of a plastic optical fibre according to a third exemplary embodiment of the present disclosure; and

[0033] is a sectional drawing showing the structure of a plastic optical fibre according to a fourth exemplary embodiment of the present disclosure.Detailed Description of Embodiments

[0034] Embodiments of the present disclosure will be described in detail below with reference to the drawings. In this description, identical or similar components are indicated with identical or similar reference numerals. The following description of embodiments of the present disclosure with reference to the drawings is intended to explain the general concept of the present disclosure, and should not be construed as limiting the present disclosure.

[0035] In addition, in the following detailed description, for ease of explanation, many specific details are expounded to provide a comprehensive understanding of embodiments of the present disclosure. However, it is obvious that one or more embodiments may also be implemented without these specific details. In other scenarios, well-known structures and devices are shown in the form of illustrations to simplify the drawings.

[0036] Exemplary embodiments of the present disclosure provide a plastic optical fibre, which acts as a light-guiding transmission medium, and may be used in fields such as communications and lighting, including, but not limited to, local area networks, fibre to home, automobile lighting or signalling, onboard or airborne communication, control and sensing systems, connecting home networks, smart homes or medical devices, etc., other lighting or light utilization systems, etc.

[0037] Exemplary embodiments of the present disclosure further provide an optical fibre transmission system comprising or equipped with such a plastic optical fibre, including, but not limited to, being used for a vehicle lamp lighting system. As an example, referring to Figs 1 and 2, an optical fibre transmission system may comprise a light source assembly 1 and a plastic optical fibre 100, the light source assembly 1 comprising a light source 10; in a communication system, the light source assembly may be a light emitter comprising a light source, a driver, a modulator, etc., and the light source 10 may comprise a laser light source or an LED light source. As an example, as shown in, the light source assembly 1 may comprise a housing 11 and a circuit board 12 that is mounted in the housing 11; the light source 10 may be mounted on the circuit board 12, and the housing 11 may be provided or formed with a heat-dissipating structure 13. One end of the plastic optical fibre 100 may be optically coupled to the light source assembly 1, to receive light from the light source 1; another end of the plastic optical fibre 100 may be connected to a light receiver or an optical fibre connector 2 for optically connecting to another device, and also is coupled to the light source assembly. It should be explained that the configuration of the system comprising the plastic optical fibre 100 shown in Figs 1 and 2 is merely exemplary, and the present disclosure is not limited to this.

[0038] In the shown embodiments, such as in Figs 3 - 7, the plastic optical fibre mainly comprises a fibre core 110 and a cladding layer 120, the cladding layer 120 circumferentially wrapping the fibre core 110 along the length of the fibre core 110, and light from the light source 10 entering the fibre core 110 propagating in the fibre core 110. The fibre core, also called a core layer, acts as a central portion of the optical fibre, and has a comparatively higher refractive index, being the main medium for transmitting light signals; the cladding layer is also called cladding and has a comparatively lower refractive index, used for reflecting and refracting light signals. It should be explained that in other embodiments, the plastic optical fibre may further comprise a coating layer and / or a protective sheath, and the coating layer coats the cladding layer to provide protection for the optical fibre.

[0039] To realize a light transmission function of the optical fibre, the refractive index of the cladding layer must be lower than the refractive index of the fibre core, and the greater the difference in refractive index between the two, the less light leakage and the higher the light transmission efficiency; therefore, a material with a lower refractive index must be used for the cladding layer. Fluoropolymer materials, such as FEP (fluorinated ethylene propylene copolymer), ETFE (ethylene tetrafluoroethylene copolymer), PVDF (polyvinylidene fluoride), etc., having a comparatively lower refractive index, are common materials for the cladding layers of conventional plastic optical fibres. For example, the refractive index of FEP is 1.34. However, fluoropolymers are PFAS materials, with “PFAS” risks.

[0040] Therefore, in a plastic optical fibre provided by embodiments of the present disclosure, at least a cladding layer 120 is made of a non-PFAS plastic material (that is, this plastic material does not contain PFAS or is PFAS-free), and preferably, the fibre core 110 and the cladding layer 120 are both made of a non-PFAS plastic material, so as to avoid “PFAS” risks, such that the optical fibre product satisfies the requirements of relevant laws and policies, and is environmentally friendly. As an example, a cladding layer 120 of a plastic optical fibre is made of a non-fluoropolymer material, and preferably, a fibre core 110 and the cladding layer 120 of the plastic optical fibre are both made of a non-fluoropolymer material.

[0041] In an exemplary embodiment, the refractive index (RI) of the fibre core 110 is greater than the refractive index of the cladding layer 120, and a difference in refractive index between the fibre core 110 and the cladding layer 120 is greater than or equal to 0.04, preferably greater than or equal to 0.06, and more preferably greater than or equal to 0.1, so that the optical fibre has good optical performance, comprising transmission distance, illuminance, optical loss, etc.

[0042] As an example, the material of the fibre core 110 may be selected from at least one of methyl methacrylate (MMA), polymethyl methacrylate (PMMA), an acrylic block copolymer, polyurethane (PU), thermoplastic polyurethane (TPU) and an acrylate polymer. Herein, the “material of the fibre core” may refer to an unmodified material and / or may refer to a modified material comprising an additive, a modifier or a dopant, such as modified PMMA, with at least one optical or physical property, such as transmittance, thermostability, refractive index and optical transmission loss, which is improved relative to the unmodified material itself. As an example, modified PMMA may comprise MAM (acrylic-based interpolymer), which is a modified material based on PMMA, and has good flexibility and weatherability.

[0043] As an example, the material of the cladding layer 120 may comprise a silicone rubber (SR) or poly 4-methyl-1-pentane (TPX) material. For example, the material forming the cladding layer may be silicone rubber, comprising thermosetting silicone rubber or solid silicone rubber (HCR), liquid silicone rubber (LSR), etc. As an example, a cladding layer can be formed by an extrusion or coating process. Likewise, the material of the cladding layer described herein may be an unmodified material or a modified material. The plastic optical fibre provided according to an embodiment of the present disclosure may be as flexible as or more flexible than a conventional flexible plastic optical fibre.

[0044] Some examples of the materials of the fibre core and the cladding layer of the plastic optical fibre are listed in the table below.Fibre coreCladding layerCladding layer forming processExample 1TPU (RI > 1.54)TPX (RI = 1.46)ExtrusionExample 2TPU (RI > 1.49)SR (RI = 1.4 ~ 1.42)Extrusion / coatingExample 3PMMA / MMA (RI = 1.48)SR (RI = 1.4 ~ 1.42)Extrusion / coating

[0045] In some examples of the present disclosure, the cladding layer 120 may be a cured silicone rubber layer. In the case where the cladding layer is formed by silicone rubber, a vulcanizing agent (such as a platinum vulcanizing agent or a double-24 or a double-25 vulcanizing agent) is used to promote a silicone rubber crosslinking reaction to cure silicone rubber on an outer peripheral surface of the fibre core. Generally, some polymer materials (comprising a raw material, modified material, doped material, additive thereof, etc.) that form a plastic optical fibre (such as a fibre core thereof) may contain N (nitrogen), P (phosphorus), S (sulphur), Pb (lead), Cd (cadmium), the polyacetylene family or a related substance, and they may cause a decline or loss of catalyst activity in the curing agent, also called vulcanizing agent poisoning, thereby causing crosslinking or curing failure of the silicone rubber.

[0046] In some exemplary embodiments of the present disclosure, as shown in Figs 6 and 7, the plastic optical fibre may further comprise a sub-fibre core layer 130, the sub-fibre core layer 130 circumferentially wrapping an outer peripheral surface of the fibre core 110 along the length of the fibre core 110 and being located between the fibre core 110 and the cladding layer 120; that is, the cladding layer 120 is not directly formed on the outer peripheral surface of the fibre core 110, rather wraps (such as by extrusion or coating) and is cured on an outer peripheral surface of the sub-fibre core layer 130, to avoid the risk of vulcanizing agent poisoning or curing failure.

[0047] Preferably, a crosslinking bonding capability between the sub-fibre core layer 130 and the cladding layer 120 is greater than a crosslinking bonding capability between the cladding layer 120 and the fibre core 110; that is, the cladding layer vulcanizes more easily on the surface of the sub-fibre core layer 130, thereby facilitating curing of the cladding layer 120 on the outer peripheral surface of the sub-fibre core layer 130. “Crosslinking bonding” refers to intermolecular bonding between two or more molecules, forming stabler molecules having a network structure, thereby improving performance of the material in strength, heat resistance, wear resistance, etc. In the present application, the sub-fibre core layer 130 ensures the retention of activity of a catalyst for initiating a vulcanizing reaction in the cladding layer 120, and, compared to the fibre core 110, the cladding layer 120 more easily vulcanizes on the surface of the sub-fibre core layer 130.

[0048] The sub-fibre core layer may also be formed by a transparent material, the addition of which does not affect the optical function of the optical fibre. The refractive index of the sub-fibre core layer 130 is greater than or equal to the refractive index of the fibre core 110; for example, preferably the refractive index of the sub-fibre core layer 130 may be approximately similar to the refractive index of the fibre core 110, for example a difference in refractive index between the sub-fibre core layer 130 and the fibre core 110 being in the range of ±0.02, and the refractive index of the sub-fibre core layer 130 being greater than the refractive index of the cladding layer 120. For example, the sub-fibre core layer 130 may be formed by the same basic material as the fibre core 110, for example being formed by an unmodified polymer transparent material. In some examples, the sub-fibre core layer 130 is formed by a transparent material with a refractive index that may further be slightly less than the refractive index of the fibre core 110 and greater than the refractive index of the cladding layer 120, but the refractive index of the sub-fibre core layer 130 must be close to the refractive index of the fibre core 110. In some examples, the material of the sub-fibre core layer comprises a polymethyl methacrylate (PMMA), thermoplastic elastomer material or another suitable material.

[0049] According to some exemplary embodiments of the present disclosure, a sub-fibre core layer is present between the fibre core and the cladding layer of the plastic optical fibre, which may solve the problem of silicone rubber vulcanizing poisoning, such that the vulcanizing and curing of the silicone rubber is more effective; moreover, since the fibre core does not directly contact the silicone rubber and does not affect curing of the silicone rubber, the material of the fibre core, according to requirements, may contain a modified material, doped material, additive, etc. for improved performance, such that there is greater choice for the material of the fibre core and greater flexibility for performance improvements.

[0050] In one example, as shown in, apart from the fibre core 110 and the cladding layer 120, the optical fibre 100 further comprises a transparent emergent light layer 140 and a reflective layer 150. The transparent emergent light layer 140 wraps an outer peripheral face of the cladding layer 120, that is, completely covers the outer peripheral face of the cladding layer 120, and the transparent emergent light layer 140 is formed by a transparent material, and is configured to transmit light from the cladding layer 120. In an embodiment shown in, a side emergent light region 160 comprises at least a portion of an outer peripheral face of a transparent emergent light layer 140. The reflective layer 150 at least partially covers the outer peripheral face of the transparent emergent light layer 140, and is thus isolated from the cladding layer 120, that is, does not contact the cladding layer 120, and the reflective layer 150 contains an opaque material, and is configured to be at least partially opposite the side emergent light region 160, to reflect light from the transparent emergent light layer 140 toward the side emergent light region 160, and the reflected light again passes through the transparent emergent light layer 140, the cladding layer 120 and the fibre core 110 and arrives at the side emergent light region 160.

[0051] According to the present invention, by means of arranging a reflective layer containing an opaque material on an outer side of a cladding layer, the plastic optical fibre 100 no longer emits light in 360 degrees, rather only emits light in a required partial region (a side emergent light region), thus reducing light leakage, improving optical efficiency, and increasing the overall luminosity of a linear light-emitting element, and requirements can be satisfied even with the lowest luminosity.

[0052] According to the present invention, a transparent emergent light layer covers a cladding layer; this transparent emergent light layer may protect the cladding layer, preventing the cladding layer from being scratched, thus avoiding undesirable bright spots caused by scratches on the cladding layer, and additionally, the transparent emergent light layer may also increase the abrasion resistance of a linear light-emitting element.

[0053] If the reflective layer covers a portion of the outer peripheral face of the cladding layer, in the case where there is poor adhesion between the material of the cladding layer and the material of the reflective layer, for example but without limitation, in the case where the cladding layer is formed of a material that does not contain fluorine, an air gap will appear between the cladding layer and the reflective layer, and since the cladding layer is transparent and the reflective layer is opaque, the air gap will be very conspicuous, severely impacting appearance. For this reason, in an embodiment of the present invention, the cladding layer is wrapped by the transparent emergent light layer; thus, even if an air gap appears, the air gap will not be easily noticeable, because the two layers are both transparent.

[0054] Preferably, the materials of the transparent emergent light layer 140 and the reflective layer 150 are chosen such that the adhesion between the transparent emergent light layer 140 and the cladding layer 120 is stronger than the adhesion between the reflective layer 150 and the cladding layer 120. In a non-limiting example, the cladding layer 120 and the transparent light emergent layer 140 are both formed of a material that does not contain fluorine. The transparent emergent light layer 140 may be formed of the same material as the cladding layer 120, or may be formed of a different material to the cladding layer 120; the present application imposes no specific restrictions in this respect.

[0055] Preferably, in order to cause more light to be emitted from the side emergent light region 160, the reflective layer 150 is configured to cover at least half of the area of the outer peripheral face of the transparent emergent light layer 140.

[0056] Preferably, the transparent emergent light layer 140 may comprise scattering elements to scatter light from the cladding layer or the reflective layer, and increase the uniformity of the illumination effect; for example but without limitation, the transparent emergent light layer 140 may be made of a scattering material or scattering units such as optical protrusions, optical depressions, optical grain and the like may be formed on an inner surface and / or an outer surface thereof. Furthermore, as shown in the figures, the transparent emergent light layer 140 has a flat outer surface, so as to meet the styling requirement for a planar appearance, but the transparent emergent light layer 140 could of course also have a curved type of outer surface, according to other styling requirements.

[0057] In another example, as shown in, the plastic optical fibre 100 also comprises a fibre core 110, a cladding layer 120, a sub-fibre core layer 130, and a transparent emergent light layer 140 and a reflective layer 150. The various layers of the plastic optical fibre 100 have the features of the embodiments described above, and are not described in further detail here. This type of plastic optical fibre 100 also has the various advantages described above.

[0058] Preferably, the layers of the plastic optical fibre 100 are formed by a co-extrusion process to reduce costs and simplify processes.

[0059] Although the present disclosure has been described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to illustrate preferred embodiments of the present disclosure demonstratively, and must not be construed as limiting the present disclosure. The dimensional proportions in the drawings are merely schematic, and must not be construed as limiting the present disclosure.

[0060] Although some embodiments of the general concept of the present disclosure have been shown and described, those ordinarily skilled in the art will understand that changes can be made to these embodiments without departing from the principle and spirit of the general concept of the present disclosure. The scope of the present disclosure is defined by the claims and their equivalents.

Claims

Plastic optical fibre, which comprises a fibre core (110) and a cladding layer (120), the cladding layer circumferentially wrapping the fibre core,wherein the cladding layer is a silicone rubber (SR) or poly 4-methyl-1-pentane (TPX) material.Plastic optical fibre according to Claim 1, whereina refractive index of the fibre core is greater than a refractive index of the cladding layer, and a difference in refractive index between the fibre core and the cladding layer is greater than or equal to 0.04.Plastic optical fibre according to Claim 2, whereina difference in refractive index between the fibre core and the cladding layer is greater than or equal to 0.1.Plastic optical fibre according to Claim 1, whereinthe material of the fibre core comprises polymethyl methacrylate (PMMA), an acrylic block copolymer, polyurethane (PU) or acrylate polymer.Plastic optical fibre according to Claim 1, whereinthe cladding layer is a silicone rubber layer.Plastic optical fibre according to any one of Claims 1 - 5, wherein the plastic optical fibre further comprises a sub-fibre core layer (130), and the sub-fibre core layer wraps an outer peripheral surface of the fibre core and is located between the fibre core and the cladding layer.Plastic optical fibre according to Claim 6, wherein the sub-fibre core layer is formed by a transparent material with a refractive index greater than or equal to the refractive index of the fibre core and greater than the refractive index of the cladding layer.Plastic optical fibre according to Claim 7, wherein the sub-fibre core layer is formed by a transparent material with a refractive index slightly less than the refractive index of the fibre core and greater than the refractive index of the cladding layer.Plastic optical fibre according to any one of Claims 6 - 8, wherein a crosslinking bonding capability between the sub-fibre core layer and the cladding layer is greater than a crosslinking bonding capability between the fibre core and the cladding layer, and the cladding layer more easily cures on a surface of the sub-fibre core layer.Plastic optical fibre according to Claim 6, wherein the material of the sub-fibre core layer comprises a polymethyl methacrylate (PMMA) or thermoplastic elastomer material.Plastic optical fibre according to Claim 6, wherein the cladding layer is cured on an outer peripheral surface of the sub-fibre core layer.Plastic optical fibre according to any one of Claims 1 -4 or any one of Claims 8 - 10, further comprising a transparent emergent light layer (140) and a reflective layer (150), wherein the transparent emergent light layer covers an outer peripheral face of the cladding layer, configured to cast light from the cladding layer, and the reflective layer is at least partially opposite an emergent light region, to reflect light from the transparent emergent light layer toward the emergent light region.Plastic optical fibre according to Claim 12, the transparent emergent light layer being made of a material that does not contain fluorine.Optical fibre transmission system, comprising:a light source assembly (1) that comprises a light source (10); andthe plastic optical fibre according to any one of Claims 1 - 13, at least one end of the plastic optical fibre being coupled to the light source assembly, to receive and propagate light from the light source.Optical fibre transmission system according to Claim 14, wherein the optical fibre transmission system is used for a vehicle lamp lighting system.

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