Superluminal motions.
Is it possible to send a bit of info with a superluminal speed? - No!
The speed of the pulse enelope is not the speed of the signal
transmission.
The envelope of the light pulse can propagate in some media at speed exceeding the speed of
light in vacuum.
- What we have to do to observe the superluminality?
Use media with dispersion. In resonant medium the dispersion is bigger,
then slowing down of the light pulse or acceleration is realized.
Sov.Journ.Quant.Electr.v.18,233,1988
Self-similar propagation of the blue detuned light pulse
in the rare-earth doped laser amplifier reduces substantially self-focusing
and demonstrates superluminal envelope velocity.
Can we send a bit of info with superluminal speed? - No!
The speed of the pulse enelope is not the speed of the signal
transmission.
In two arms of optical chain on the picture below
nonlinear gain provides compensation of linear delay.
In examples, shown below,
The two indetical fiber rings are included in optical arms.
The upper path is longer, hence in the absence of gain in the upper
loop the pulse moving along bootom path arrives to detector before the
pulse moving along upper path. Look oscilloscope traces and
animation.
Another situation is shown on the next picture.
The upper fiber loop is resonantly pumped by two VCSEL diode lasers.
Thus, the superlminal propagation is possible.
As a consequence, the upper pulse arrives faster than lower.
Why?
Look oscilloscope traces and
animation.
This effect had been discovered by the group of N.G.Basov,R.V.Ambartzumyan,
V.S.Vuev,P.G.Kryukov and V.S.Letokhov in 1965.
You may also read some other pages on
superluminality.
Используются технологии
uCoz