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Soliton Pulses   World Population
Soliton Pulses  in Fiber Conventional Fiber Communications  
50 Gbit/sec No Repeaters Speed of Light, Sound, & other Constants Doppler Shift
Other Soliton URLs   Time is Relative

Soliton P u l s e s 

{As of ~ 1995}
There is a new fiber optic data transmission scheme that utilizes something called Soliton Pulses. These are very short bursts of light generated in an Erbium-doped Fiber LASER. Soliton light can be used to transmit data at rates in excess of 50 Gb/s, at distances over 19,000 km of Dispersion-Shifted Fiber, requiring no repeaters, and with no errors. This data rate is the equivalent of sending 6,200 bibles per second. At this rate, one bible could be sent to everyone on earth--5.5 9people--in about 10 days. 

In the case of repeaters, in a long-haul fiber: instead of converting the light into electrical signals, amplifying, correcting errors, retiming and retransmitting light pulses, an optical amplifier is used. It consists of about 30 meters of Erbium-doped fiber, assorted filters and beam splitters, and pumped by a 15 mW LASER diode operating at 1550 nm. This arrangement adds about 30 dB of gain with no appreciable noise. Also, the bandwidth of this amplifier is on the order of 40 THz. At this rate, one bible could be sent to everyone on earth, 5.5 9 people, in about 18 minutes. 

The Shortest LASER pulse, to date, is ~10 Femtoseconds (10 -15 sec). Light would travel 1/8th the thickness of a sheet of paper in that time. 10 Fsec is to one second as one second is to 3.2 million years. 

  A Soliton Pulse is: a pulse of light--of sufficient intensity and correct wavelength --traveling down a special non-linear optical fiber known as, Dispersion-Shifted Fiber, is classified as a Soliton Pulse. This Soliton light pulse exhibits a unique characteristic of getting shorter--not longer, as conventional wisdom would dictate. Due to the non-linearly of the fiber in the presents of light exceeding some quantum threshold of intensity--the leading edge of the pulse is being overtaken by the faster trailing edge. That is, the leading edge of the light is undergoing a Doppler Red-Shift, while the trailing edge is experiencing a DopplerBlue-Shift. The result of this effect is a shortening of the pulse duration, with a corresponding increasing Peak Power. 

As the pulse looses energy (joules) over distance, it increases in Peak power--thus insuring itself's staying above the peak threshold of the fiber needed for the phenomenon in the first place!

..
The Dichotomy of Soliton Pulses in Dispersion-Shifted Fiber
Starting Out            Midway                Destination 
In normal Dispersive finite bandwidth media, the greater the Distance traveled, there is a Spreading of the pulse width, i.e., Signal Bandwidth is reduced (resulting in Inter-symbol Interference).

However, the opposite is true with Soliton pulses in Dispersion-Shifted Fiber.  As can be seen in the above figure, the leading edge of the light pulse is undergoing a Doppler  Red-Shift, while the trailing edge is experiencing a Doppler Blue-Shift, narrowing the pulse; which Spreads the Bandwidth and Increases the Peak Power.

Even though Average Power is Decreasing, the narrowing pulse forces the Peak Power to Increase--assuring the continued operation in the Nonlinear region of the Dispersion-Shifted Fiber.
 

..
Conventional Fiber Communications 1.7 GBit/sec
[Light to Electronic] [Electronic to Light] (1800cu ft.) Repeaters spaced ~ 20 km
..
Soliton Pulses  in  Dispersion-Shifted Fiber Communications, 25 Gbit/sec 
<-- 19,000 km -->
With No Errors
Optical/Light Amplifier Repeaters (0.5cu ft.) spaced ~ 30 km - 100 km
..
> 50 Gbit/sec No Repeaters Needed
<-- 19,000 km -->
With No Errors
No Repeaters Needed
..

More Info on Solitons
http://www.sfu.ca/%7Erenns/lbullets.html    Excellent!
LOS ALAMOS NATIONAL LABORATORY 
http://people.uncw.edu/hermanr/Research/solitons.htm
..
World Population
Just how many is 5.5 Billion?
  They could all Live in Brazil
They could all Lie Down in West Virginia
They could all Stand in Jacksonville
..
 
Distance Traveled

Time

 
 Millisecond
1 - 3  = 1 msec
300 km 
186.4 miles
is to one second as one second is to: 
  16.6 Minutes
 Microsecond
1 - 6  = 1 µ sec
300 m 
984.25 feet
is to one second as one second is to: 
  11.574 Days
 Nanosecond
1 - 9  = 1 nsec
300 mm 
11.8 inches
is to one second as one second is to: 
  31.7 Years
  Picosecond
1 -12 = 1 psec 
300µ 
12/1000 inches
is to one second as one second is to: 
  31,688 Years
 Femtosecond
1 -15 = 1 fsec 
300 nm 
12/1,000,000 inches
Thickness of 1 sheet of paper 
divided into ~ 130 parts 
is to one second as one second is to:
  31,688,000 Years
..
Velocity of Light in:
Free Space =
Water =
Quartz =
Glass ~ 
Diamond =
-
186,282 miles/sec
140,000 miles/sec
110,000 miles/sec
122,000 miles/sec
 77,000 miles/sec
Velocity of Sound in Air:
  at sea level @ 32°F  (0°C) =
  at sea level @ 72°F (25°C) =

1,088 ft/sec; 337.28 m/sec = 742 MPH
1,136 ft/sec; 352.16 m/sec = 775 MPH
Velocity of Sound in Water:
 @ 32°F (0°C)=

  4,938 ft/sec; 1,530.78 m/sec =   3,366 MPH
Velocity of Sound in Glass: 18,046 ft/sec; 5,594.26 m/sec = 12,307 MPH
..
~Doppler Shift ~
Frequency Shift per 1 MPH of Velocity
 Fbeat = 89.4 (V/wl) 

 fr/ft = 1-(V/C)

    where:
 V = MPH
 C = Light Velocity in MPH 
 Fbeat = in Hz 
 wl = in cm (Wavelength)

  C = 186,282.397 miles/sec 
  C = 299,792,458 meters/sec 
  1 meter = 39.37 inches


 


 
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