Information Technology Reference
In-Depth Information
For European standards, you should consult IEC 825-1 and IEC 825-2. These
standards cite levels of operation that differ from the U.S. standards.
In addition to the safe classes of laser operation mentioned above, you should
be aware that some Class 1 laser sources are theoretically capable of operating at
levels that might be harmful to the eye. In addition, some people are more sensitive
to very bright point-source light and can suffer brief effects that interfere with nor-
mal vision. If you have ever had a laser pointer flash in your eyes, you may have
experienced this problem.
The future of optical fiber is secure. Fiber cable clearly provides an extreme amount
of potential bandwidth, particularly in the case of single mode fiber. At present, the
utilization of this incredible bandwidth is limited primarily by the speed of available
optics and whether you put multiple wavelengths on the fiber.
Currently, 10 Gb Ethernet is in the corral, and transmission beyond that is not
only theoretically possible, it is happening right now. One factor that will influence
the introduction of these bandwidths is the need for speed. Another factor is cer-
tainly the ability of the existing fiber plant (if such exists) to support these advanced
speeds. Future equipment interface implementations may actually borrow the mul-
tiple pair technique from copper cabling. Another viable implementation uses mul-
tiple wavelengths to multiply the effective bandwidth of the fiber.
In the end, it is all a matter of cost. If the demand is there, the volume will
increase, and the price will fall. The 100 Mbps links were initially very expensive,
but their price has rapidly fallen to that level once occupied by 10 Mbps. The 1000
Mbps links will definitely do the same, as in fact they already are. Now 10 Gbps
links are available, for about the same cost that gigabit was when it was introduced.
Fiber is definitely in our future.
