This preview shows page 1. Sign up to view the full content.
Unformatted text preview: current practical limit is 10
Gb/second, primary limited - need for
100 Gb/sec. has been achieved in Lab, and >
50,000 Gb/second could be achieved. Instead of frequency, light signals are
described in terms of wavelengths, ë.
ë = c/f,
where c is the speed of light, 3*108
meters/second. Wavelength bands for optical fiber are
centered at 0.85, 1.3, and 1.55 microns.
In these bands, attenuation is only about
0.2 dB per kilometer. 1 micron = 10-6 meters. Thus, at 1.3
f = 3*108/(1.3*10-6) = 2.31*1014 herz!
A deviation of 1 gigaherz = 109 hz from
this center is less than 1/100,000 of the
The bands are about 25,000-35,000
Can send thousands of kilometers, small
The 0.85 micron band has more
attenuation, but the materials and devices
are cheaper. Optical signaling is generally by onoff pulses.
Optical interfaces can be passive or
Passive: Passive Star broadcast: Light coming into junction splits about
equally. With n receivers, each received
power is 1/n of original. Active:...
View Full Document
This document was uploaded on 04/03/2014 for the course EE 362 at Penn State.
- Fall '08