Plastic optical fiber

Polymeric optical fibers ( POF, engl. For Polymeric optical fiber or plastic optical fiber ), fiber optics are made ​​of plastic, which are used primarily for data transmission, come in the form of side light fibers but also in the ( indirect ) lighting used. In particular, in the short-range data transmission are POF as an alternative to fiberglass - currently technically significant optical waveguides.

Construction

A standard polymer fiber is 1 mm thick and consists of a 0.98 mm-thick core made from polymethylmethacrylate (PMMA), and a thin coat. To allow a light guide by the effect of the total reflection in the core consists of the usually very thin coat of fluorinated PMMA, which has a lower refractive index. The core diameter moving from 0.06 to 1 mm, making simple connections can be realized without problems. Furthermore, thus the commonly used for the connection of optical fibers splicing, and the associated unnecessary effort, be dispensed with, as a rule. The maximum operating temperature of standard POF is about 60 ° C, the numerical aperture of 0.5.

The advantages of POF are - similar to fiberglass - in their light weight, their high flexibility and their insensitivity to electromagnetic interference (electromagnetic compatibility). Due to the compared to the fiberglass lower production costs as well as the simple and nearly universal connection techniques are POF particular application in short data transmission distances, such as within rooms, technical equipment, mechanical equipment, or even passenger cars ( see also: MOST - bus).

The main drawbacks of the POF are their high attenuation ( about 0.1 dB / m at a wavelength of 650 nm) as well as the technical effort in the production of graded-index fibers and single-mode fibers. Due to the high attenuation, the maximum length of the fiber without amplification about 100 to 120 m. A high dispersion leads to a low in comparison to glass fiber maximum bandwidth -length product of a transmission line.

For use in the data transmission

In practice, transmission speeds of about 100 Mbit / s at 30 m cable length can be achieved with polymer fibers. In the context of attempts with graded-index fibers already 1.25 Gbit / s were s reached more than 1 km and in 2010 10 Gbit / over 15 m in 2002, however. The transmission window of the step-index POF are located in the visible region of the electromagnetic spectrum, that is, in the light. As transmitter diodes are generally (LED) with a wavelength of 650 nm. It is true that the blue- green range is highly transparent, but no efficient and inexpensive emitters are available so far, which is why the wavelength range hardly plays a role in practice. In addition, the maximum spectral sensitivity of the silicon photodiode is also used to receive the long wavelength end of the light spectrum.

The coupling of light emitting diodes with standard polymeric fibers, i.e., the POF of 1 mm in the core and 2.2 mm in outer diameter can be, for example, by a are integrally formed on the LED sleeve together with the lens, in which the polished or only cut end of the fiber is fixed. Furthermore, there are also plug-in systems for repeat use, which are, for example, in the digital audio signal transmission is used ( see also: Toslink). For thinner, less disperse graded- well laser diodes are used as transmitters.

Former products

GRINIFIL was the trademark name of a group of optical fibers that have been mentioned in the GDR plastic optical fiber.