| 单词 | POF (Plastic Optical Fiber) |
| 释义 | POF (Plastic Optical Fiber) A type of multi-step step-index, multimode optical fiber (MMF) manu- factured of plastic rather than glass, POF has a large diameter core and a thin layer of cladding comprising multiple steps in index of refraction (IOR).The outside diameter of the fiber typically is approximately one millimeter (1.0 mm). The core is very large in diameter (960 microns), and the cladding only 40 microns or so. POF is designed to couple to a light-emitting diode (LED) emitting red light in the 650 nm window, which is in the visible light spectrum. In combination, the large mode field created by the large diameter core, the short wavelength of the signal, the use of LEDs as light sources, and the high IOR of the plastic relegate POF to short-haul, low-bandwidth applications. POF offers advantages in certain applications due to its flex strength, ability to withstand extremes of temperature (–40 to +85 degrees Celsius), and ability to withstand a bend radius of down to 25 mm with no break or damage. Consumer POF, which is used in consumer electronics, automobile wiring, and cold lighting, comprises a core of polymethyl methacrylate (PMMA), a type of acrylic, and cladding of fluorinated polymers. Perfluorinated polymer fibers are commonly used for much higher-speed applications such as data center wiring and local area network (LAN) wiring. Running at a wavelength of 650 nm, POF can support data rates of up to 400 Mbps over distances up to 100 meters, which compares very favorably to standardized Cat 5 and Cat 5e UTP, as well as Cat 6 and the developing Cat 7 standards. While its speed rating does not compare favorably with glass optical fiber (GOF), the MFA Forum has approved POF as a viable medium for use in ATM applications at speeds up to 155 Mbps for horizontal links up to 50 meters in length. The IEEE included POF in the 1394b FireWire standard, also for links up to 50 meters. See also bend radius, Cat 5, Cat 5e, Cat 6, Cat 7, cladding, core, FireWire, flex strength, GOF, IOR, LED, MMF, short haul circuit, step-index fiber, and window. 74570c16.qxd 9/11/07 12:27 PM Page 381 |
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