Plastic optical fiber
Plastic optical fiber (POF) (or Polymer optical fibre) is an optical fiber that is made out of polymer. Similar to glass optical fiber, POF transmits light (for illumination or data) through the core of the fiber. Its chief advantage over the glass product, other aspect being equal, is its robustness under bending and stretching. Optical fiber used in telecommunications is governed by European Standards EN 60793-2-40-2011.
Traditionally, PMMA (acrylic) comprises the core (96% of the cross section in a fiber 1mm in diameter), and fluorinated polymers are the cladding material. Since the late 1990s much higher performance graded-index (GI-POF) fiber based on amorphous fluoropolymer (poly(perfluoro-butenylvinyl ether), CYTOP) has begun to appear in the marketplace. Polymer optical fibers are typically manufactured using extrusion, in contrast to the method of pulling used for glass fibers.
Characteristics of PMMA POF
- PMMA and Polystyrene are used as the core, with refractive indices of 1.49 and 1.59 respectively.
- Generally, fiber cladding is made of silicone resin (refractive index ~1.46).
- High refractive index difference is maintained between core and cladding.
- High numerical aperture.
- Have high mechanical flexibility and low cost.
- Industry-standard (IEC 60793-2-40 A4a.2) step-index fiber has a core diameter of 1mm.
- Attenuation loss is about 1 dB/m @ 650 nm.
- Bandwidth is ~5 MHz-km @ 650 nm.
Applications and Recent Developments
POF has been called the "consumer" optical fiber because the fiber and associated optical links, connectors, and installation are all inexpensive. Due to the attenuation and distortion characteristics of PMMA fibers, they are commonly used for low-speed, short-distance (up to 100 meters) applications in digital home appliances, home networks, industrial networks (PROFIBUS, PROFINET), and car networks (MOST). The perfluorinated polymer fibers are commonly used for much higher-speed applications such as data center wiring and building LAN wiring. Polymer optical fibers can be used for remote sensing and multiplexing due to their low cost and high resistance.
In relation to the future requirements of high-speed home networking, there has been an increasing interest in POF as a possible option for next-generation Gigabit/s links inside the home. To this end, several European Research projects are active, such as POF-ALL  and POF-PLUS . Several standardization bodies at country, European, and world-wide levels are currently developing Gigabit communication standards for POF aimed towards home networking applications. It is expected the release at the beginning of 2012. 
One future Gigabit POF standard is based on multilevel PAM modulation a frame structure, Tomlinson-Harashima Precoding and Multilevel coset coding modulation. The combination of all these techniques has proven to be an efficient way of achieving low-cost implementations at the same time that the transmission theoretical maximum capacity of the POF is approached.
Since 2014 a full family of PHY transceivers are available in the market enabling the design and manufacturing of home networking equipment truly delivering Gigabit speeds into the home. Other alternatives are schemes like DMT, PAM-2 NRZ, DFE equalization or PAM-4. VDE standard was published in 2013. After the publication the IEEE asked VDE to withdraw the specification and bring all the effort to IEEE. VDE withdrew the specification and a CFI was presented to IEEE on March 2014. An IEEE study group has been meeting since then.
POF fiber also has applications in sensing. It is possible to write fiber Bragg gratings in single and multimode POF. There are advantages in doing this over using silica fiber since the POF can be stretched further without breaking, some applications are described in the PHOSFOS project page.
In 2008 researchers of the Technical University Eindhoven published their results of the evaluation of POF for Gigabit-Ethernet transmissions over a distance of 100m using low-cost existing components. They came to the conclusion that it was a viable technology and more or less ready for mass market. However the IEEE has not yet passed any of the proposals into a final extension of the existing ethernet standards.
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