In recent years, in order to reduce the cost of fiber access optical fiber network end-users, some well-known domestic and foreign universities and research institutions, manufacturers racing to develop cheap, connecting a simple, reliable plastic optical fiber and communication systems. This article briefly describes the progress of the plastic optical fiber structure, materials, manufacturing methods, performance and communication systems.
Plastic optical fiber structure: the short-distance communication using plastic optical fiber, its profile of the refractive index distribution can be divided into two types: step-index plastic optical fiber and a graded-index plastic optical fiber. Step index plastic optical fiber due to its mode dispersion interaction between people shot reflection of light occurs repeatedly, the emitted waveform relative to the incident waveform broadening, its transmission bandwidth of tens to hundreds of MHz • km. Gradient refractive index gradient plastic optical fiber to optimize distribution suppression mode dispersion, from reducing the manpower of the material dispersion, and thus obtain a bandwidth of up to hundreds MHZ • km to several GHz • km gradient plastic optical fiber.
The plastic optical fiber materials: When the plastic optical fiber material is selected, the main consideration is the material itself is a translucent, refractive index, etc.. The core material in addition should be good transparency, uniform optical refractive index appropriate, attention should be paid to the mechanical, chemical stability, thermal stability, processing and cost factors.
Currently, often selected for the plastic optical fiber core materials are: poly (methyl methacrylate) (PMMA), polyphenylene propylene (PS), polycarbonate (PC), fluorinated poly methyl acrylate (FPMMA) and perfluoro resin and so on. Often selected as the plastic optical fiber cladding materials are: poly (methyl methacrylate), fluorine plastic, silicon resin or the like.
The manufacture of plastic optical fiber: the quartz glass optical fiber manufacturing method is completely different: extrusion method and interfacial gel method, the communication method of manufacturing a plastic optical fiber.
The extrusion method is mainly used in the manufacture of the step-type plastic optical fiber. The process steps are as follows: First, as a core of poly (methyl methacrylate) the monomers methacrylamide methylphenidate through after purified by distillation under reduced pressure, together with a polymerization initiator agent and a chain transfer agent is fed to the polymerization vessel together, Then the container was placed in an electric oven heating, the placement of a certain time, so that the monomer is completely polymerized, and finally, will be filled with a fully polymerized poly (methyl methacrylate), the container was heated to the drawing temperature, and dry nitrogen pressurized molten polymer from the upper end of the container, the bottom of the container mouth is extrusion of a plastic optical fiber cores at the same time so that the extruded core coated with a layer of low refractive index polymer is made of bands jump-type plastic optical fiber.
Gradient type of plastic optical fiber manufacturing method of the interfacial gel method. The interfacial gel method, the process steps are as follows: the first high refractive index dopant in the core monomer to prepare the the core mixed solution, followed by the initiator and a chain transfer agent into the core to control the rate of polymerization, the polymer molecular size the mixed solution, and then the solution was put into a selected as the cladding material within the hollow tube of poly methyl methacrylate (PMMA), and finally the mixed solution of PMMA with a core tube placed in an oven at a certain temperature and time conditions of polymerization. In the polymerization process, the PMMA tube gradually a mixed solution of swelling, the gel phase is formed in the inner wall of the PMMA tube. In the gel phase molecular movement speed slows down, the polymerization reaction is accelerated due to the “gel effect”, the thickness of the polymer is gradually thickened, the polymerization was terminated on PMMA tube center, thereby obtaining a refractive index along radial gradient distribution fiber preform law, the last before plastic optical fiber preform is fed into the furnace heat drawn into graded-index plastic optical fiber.