Plastic optical fiber (POF) is made of highly transparent polymers such as polystyrene (PS), polymethyl methacrylate (PMMA), polycarbonate (PC) as the core material, and PMMA, fluoroplastics, etc. as the skin material. Fiber-like (optical fibers). Different materials have different light attenuation properties and temperature application ranges. Plastic optical fiber can not only be used in the last 100-1000 meters of the access network, but also in various vehicles, planes, and other vehicles. It is an excellent short-distance data transmission medium.
Plastic Optical Fiber. As of 2014, the optical fibers used in communication optical cables are basically made of silica optical fibers, which are composed of high-purity silica SiO2 with an appropriate amount of dopant. In recent years, plastic optical fibers (POFs), which are optical fibers made of a light-transmitting polymer, have also been gradually developed. Because the mature and simple drawing process of the polymer can be used, the cost is relatively low, and it is relatively soft, strong, large in diameter (about 1mm), and low in splicing loss.
There are two main materials for making POF: one is polymethyl methacrylate polymer PMMA (Polymer Polymethylmethacrylate); the other is fluorinated polymers (Perfluorinated polymers)
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1. Attenuation
The attenuation of plastic optical fiber mainly depends on the scattering loss and absorption loss of the selected material. To be used as a communication-grade plastic optical fiber, one of the most basic requirements is that the attenuation of the PMMA plastic optical fiber should be low, preferably less than 180dB/km.
2. Bandwidth
The graded plastic optical fiber is an optical fiber with a gradient distribution of refractive index, and its refractive index gradually decreases from the core to the cladding. As long as the gradient refractive index distribution formed is suitable, the effects of suppressing modal dispersion, maintaining a large numerical aperture, and controlling the broadening of the outgoing light wave relative to the human light wave can be obtained. If the refractive index distribution is appropriate, the material dispersion becomes the main factor in determining the transmission bandwidth. As long as sufficient attention is paid to material dispersion when selecting, it is completely feasible to obtain a bandwidth of several Ghz·km.
3. Heat resistance
Most importantly, the heat resistance of a plastic optical fiber is mainly determined by its compositional properties. The material composition with good heat resistance determines that the plastic optical fiber has better heat resistance. The indicators for judging the heat resistance of materials include glass transition temperature, Vicat softening point, thermal deformation temperature and other indicators.
4. Connectivity
Communication plastic optical fibers mostly use optical fibers with a diameter of 1 mm, which is 8 to 20 times that of silica optical fibers. Thick plastic fiber is much easier to connect than silica fiber
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Plastic optical fibers are lighter, softer, and more resistant to damage (vibration and bending). Plastic optical fibers have excellent tensile strength, durability and small footprint. These advantages make the successful application of plastic optical fibers in automobiles particularly important. The interior of a typical luxury car consists of at least several kilometers of copper wires and cables, which greatly increases the weight and cost. The same goes for planes, trains, and all other means of transportation.
Due to the large diameter and numerical aperture of the plastic optical fiber, the light transmission capacity is large. Plastic optical fiber has a much higher bandwidth capability than copper-based transmission media (twisted pair and coaxial cable). The higher the frequency of transmission, the lower the cost of using plastic optical fibers.
Cutting, routing, bonding, polishing and other processing of plastic optical fibers are easy. Due to the larger diameter, plastic optical fiber installation and connection to devices, light sources, detectors, etc. are easy and low-cost, and non-professionals can also perform these operations. Preparing the connection of the plastic optical fiber takes no more than 1 minute and no special tools are required. Even the simplest scissors can be used to cut plastic optical fibers. The plastic optical fiber transceiver module uses red light with a wavelength of 650nm, which is very safe, and the user can easily judge whether the connection of the optical fiber is successful. In addition, plastic fiber optic connections are not sensitive to dust and debris trapped on the end face.
Plastic optical fibers do not emit radiation and are completely immune to electromagnetic and radio frequency interference and noise. This is especially important for video and audio streaming, as it is clear that these disturbances and noise affect the quality of the image and service. Plastic optical fibers can be laid side by side in the same duct or in the same harness as the copper cable. Plastic optical fibers do not generate noise and do not negatively affect the current pipe network.
The cost of POF systems is low. It is said to cost less than $20 per connection for home consumer electronics, home networking, and cars including stereos, DVDs, VCRs, and more. So these devices are available in general stores.
Data transmission through plastic optical fibers is unlikely to be eavesdropped, so plastic optical fibers are very suitable for some occasions with high security requirements.
While silica fiber is widely used for long-distance trunk communications and fiber-to-the-home, plastic fiber has been referred to as "popular" fiber, citing the lower overall cost of plastic fiber, associated connections, and installation. In the overall solution of fiber-to-the-home and fiber-to-desktop, plastic optical fiber is the supplement of silica fiber, which can jointly build an all-optical network.
Compared with silica fiber, POF has the following advantages: low modulus, large core diameter (0.3-1.0mm), simple POF connector can be used for splicing, even if the optical fiber splicing center alignment produces 30μm deviation, it will not affect Coupling loss; large numerical aperture (about NA0.5), the light receiving angle can reach 60°, while the quartz fiber is only 16°, cheap LEDs can be used, and the coupling efficiency is high; good flexibility, easy to process and use; in the visible light region Has a low loss window; light weight; low cost and processing costs.
Compared with other transmission media in local area network systems, POF network also has obvious advantages: POF is not sensitive to electromagnetic interference, and does not emit radiation, the attenuation under different data rates is constant, the bit error rate is predictable, and it can be used in electrical noise environments. Its longer size can reduce the requirements for tolerance control in joint design, so the cost of forming a network is lower, etc.
