Page 50 - Optical Switching And Networking Handbook

03_200023_CH02/Batesx 1/17/01 8:17 AM Page 35

Basic Fiberoptics Technologies 35

Increasing Frequency
Figure 2-5
The light spectrum
used in fiber Ultraviolet/400 nm
(Corning)
Violet/455 nm
Blue/490 nm

Visible
Spectrum
Green/550 nm

Yellow/580 nm
Orange/620 nm
Red/750 nm
Infrared/800 nm
Multimode, Short Wavelength 850 nm

Multimode, Single-mode, Fiber Optic
Long Wavelength 1300 nm Applications
Single-mode,
Long Wavelength 1550 nm

Longer Wavelength

Source: Corning

When a short blast (pulse) of light is sent down the glass, it has
the problems mentioned earlier. The light can be subject to several
impairments acting on it at the same time. The light beam actually
degrades quickly. The received light beam will be different from the
one that entered the glass initially. It may be weaker (signal loss),
smeared out across a wider frequency (time is lengthened), or dis-
persed (spreading it across a larger spectrum). Each of these char-
acteristics will have an impact on the reception of the information.
The impairments are shown in Table 2-2 with a summary of each of
the major concerns.
Looking at the frequency spectrum, a window of frequencies is
used to produce the signal in the normal operating wavelength, as