**4.1 Glass fibers vs. polymeric fibers vs. CAT**

Optical waveguides are made of optical glasses or assembled, partially assembled, provided with plug connections cables and lines for the transmission of light in the visible as well as ultraviolet or infrared range. Fiber optic cables form flexible connections for the transmission of optical signals. Depending on the application, the fiber optic cables consist of Quartz glass, e.g. pure silicon dioxide (SiO2) or organic glass Polymeric fibers consist of acrylic glass [28]. From a physical point of view, both optical waveguides are dielectric waveguides.

Today, fiber optic cables [29] are mainly used as a transmission medium for wired telecommunication processes. In addition, there are diverse applications: fiber optic cables for laser radiation for material processing [30, 31], in medicine for lighting and imaging purposes: microscope lighting [32], endoscopes [33], decoration lighting [34], for contact-free sensors [35], in measurement technology, e.g. in infrared thermometers and spectrometers [36].

Today, fiber optic cables are increasingly used for information transmission, in telecommunications and also in the area of computer networking. The term optical fiber is standardized in DIN 47002 and VDE 0888 and means that it is a conductor in which modulated light is transmitted. The fiber optic cable can be made of fiberglass or plastic. With plastic fiber-optic cables, the so-called POF, high transmission rates can be achieved, which can be up to several million bit/s. Furthermore, POF are insensitive to electromagnetic interference, largely secure against eavesdropping and have very low attenuation values compared to copper conductors.

A comparison of different fiber optical waveguides in glass and in polymeric materials are depicted in **Figure 8**. There are multimode fibers (MMF) available in two sizes, 62.5 or 50 microns, and four classifications: OM1 (62.5/125 μm), OM2, OM3, OM4 (50/125 μm) [37]. The GOF fiber type for SoHo applications is the multimode GOF with a diameter 50 μm core and 125 μm cladding. The bandwidth of this device is typically 1–10 GBit/s over 100–500 m. The POF has a very limited bandwidth of 1 Gbit/s over 100 m link length in Ethernet networks.

As depicted in **Figure 9** the single mode GOF (SMF) offers the highest bandwidths of over 10 Gbit/s, which go well beyond the bandwidths required in the

**Figure 8.**

*Dimensions of GOF and POF fiber types.*

#### **Figure 9.**

*Transmission speeds of single mode and multimode GOF, POF and CAT for inhouse applications.*

SoHo area. This is why the SMF still plays a subordinate role in the short-term computing area in buildings. On the other hand, the multimode GOF (MMF) with bandwidths of 1 Gbit/s has significantly higher application potential, since the connectors and other active components such as transmitters and receivers are significantly cheaper than those of SMF components. The POF has significantly expanded its bandwidth potential in recent years and with gradient index POF (GI-POF) can also allow up to 10 Gbit/s over 50 m transmission distance, but has only been investigated in research studies to date. The step index POF (SI-PF), which can be used commercially with a maximum of 1 Gbit/s, is significantly worse in terms of transmission bandwidth. On the other hand, experimental studies show, that Wavelength Division Multiplex (WDM) techniques [38] applied in the POF spectrum of 400 nm to 780 nm can overcome the bandwidth restrictions and can realize more than 15 Gb/s via 4 chromatic transmission channels [39]. Additional WDM sources can extend the overall bandwidth to more than 40 Gb/s [40].

The copper technology of the CAT cables currently also achieves gigabit transmission speeds, but is very susceptible to installation errors such as bending radii that are too small. However, the CAT cable connection has the advantage of passive networking without further active transmitter/receiver elements.

#### **4.2 POF fibers for inhouse applications**

For signal transmission over short to medium distances of up to approx. 100 m, optical waveguides made of acrylic glass (polymethyl methacrylate or PMMA), so-called POF, are used.

Polymer fiber technology for optical data transmission has developed very dynamically over the past 10 years [41]. Starting with simple transmission options for the consumer sector such as digital links between DVD players and preamplifiers in the home multimedia sector (TOSLINK [42] system) with data rates of a few Mb/s, the technology has now established itself in the automotive sector with the use of MOST bus [43]. Here, POF is used in the visible wavelength range, since the components at this level of application must be manufactured as cost-effectively as possible for the end user. Mobile multimedia applications are of particular importance in the automotive sector, where over 50 vehicle types (approx. 15 million vehicles) have been equipped with POF bus systems since its introduction in 2001.

#### *Optical Inhouse Networks DOI: http://dx.doi.org/10.5772/intechopen.98921*

In addition to the higher data rate and the resulting improved integration of multimedia applications in busses or automobiles, considerable weight reductions in the cable of 30% are also achieved [44, 45].

For these reasons, optical data transmission is increasingly being used in close proximity, e.g. in office and house communication, in production facilities, in medical technology or in bus systems for cars, trains and planes.

In the following, the optical basics of fibers, called POF (polymer optical fibers) for short, their active and passive components for network technology and their fields of application in the in-house area are presented.

## **4.3 Optical properties and advantages of POF**

Optical fibers consist of a highly transparent core, a cladding and a protective coating and/or buffer. The light-guiding core is used to transmit the signal. The cladding has a lower optical refractive index (density) than the core. As a result, the cladding causes total reflection at the boundary layer and thus guiding the radiation in the core of the optical waveguide. However, light can also get into the cladding through bending or coupling at the beginning of the route. This is usually undesirable and the jacket and protective coating are therefore designed in such a way that this light is strongly attenuated.

The outer protective coating helps against mechanical damage and protects the fiber from environmental influences. The POF consists of PMMA (acrylic glass), has a core diameter of approx. 1 mm (**Figures 10** and **11**) and has a bandwidth of

**Figure 10.** *Attenuation diagram of POF in the visible regime.*

**Figure 11.** *Schematic draw of a polymeric fib.*


#### **Table 2.**

*Comparison of GF, CAT and POF transmission connections in SoHo environment [46].*

100 Mb/s over 100 m, which can be expanded to 1000 Mb/s with special modulation techniques and laser transmitters. The advantages of POF in laying technology are obvious in several areas compared to WiFi, powerline/dLAN or CAT solutions (see **Table 2**, [46]):

	- Very inexpensive, easy to work with
	- Low weight, very small diameter: 1/10 of copper cables
	- More flexible and cheaper than glass fiber optic cables
	- Easy handling
	- EMC insensitivity
	- Better insurability
	- Security against eavesdropping
	- Short-circuit protection, free of hum loops
	- Data rates can be expanded in a future-proof manner (investment security)
	- Several signals can be transmitted on one fiber
	- Significantly cheaper and easier to lay than glass fibers

#### *Optical Inhouse Networks DOI: http://dx.doi.org/10.5772/intechopen.98921*

The 1 mm fiber type is the cheapest to manufacture and is therefore used in 95% of all commercial applications. The refractive index is constant over the entire core cross-section (SI-POF). With other fiber types, for example gradient index fibers (GI) or multi-level index fibers (MSI), significantly higher bandwidths (currently 2.3GHz/100m) can be achieved in the laboratory, but these do not play a role in the consumer market segment. The advantages of the standard SI-POF lie in the wide availability, the very low price, the favorable attenuation behavior (**Figure 10**) a very high numerical aperture, which enables a simple and effective coupling and extraction of light.
