IGBT Modules - Technologies, Driver and Application (Second Edition) - page 227

The basis of the transmitter for fibre optics is a light emitting laser diode VCSE
or a
light emitting diode (LED). This sets the wavelength with which the system works.
Typical wavelengths are 850nm, 1300nm and 1550nm. The wavelength contributes
towards the degree of attenuation of the light signal. Thus, a fibre optic cable, in reality,
is limited in length due to losses of the light intensity caused by contaminationwithin the
cable. At the end of the cable theremust still be sufficient light energy arriving to control
the receiver. The receivers are light sensitive semiconductors, which convert the
incident light beam into electrical energy.
Optical fibres themselves are fibreglass or plastic cables that are characterised by high
purity (but not 100% free of contamination). Inside them the emitted light is reflected at
the border area of the inner fibre core. Therefore, the fibre optics can be layed out in a
very flexible way. However, the cable cannot be bent at will. Aminimum bending radius
must beobserved duringassembly.
Fig. 6.14
Exampleof the construction of anoptical fibre
The application of fibre optics in power electronic systems is quite straight forward if the
recommended temperature range is obeyed. Today, fibre optic systems can cover
distances of several 100mwith data transfer rates of up to
. However, in power
electronic systems the data transfer rate is not the focus. Rather, propagation
tolerances are an important criterion. In addition, the reliability and longevity of these
systems areessential.
hows the current standarddesigns for transmitters and
receivers in industrial and traction applications.
VCSEL (Vertical-Cavity-Surface-Emitting Laser) ismainlyused for high speed data transmission.
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