Wait... no telescopes, very close distances...
only a laser, with a photon limiter like a dark window, "close" like
10mm or so... just the space required for the laser optics plus the
"limiter", and a photon counting detector that can be an APD or a PMT,
it depends on the size required and scale of integration.
The "idea" came because my professor told me that laser is a light
source composed by a limited number of harmonics, so close the ones as
some nm wavelengths, to get these lights can be directional and
manouverable: if these should be the carachteristics of lasers (a laser
expert can correct me), photons emitted by this type of light source
should hit the detector at a constant rate. The (very dark) limiter
serves to regulate the photon flux so a very limited number of photons
reach the sensor part.
The question was if the photodetector could use the individual photon
detection as clock tick, and if these ticks can be regular in frequency.
Many have replied that it would be noisy: phase noise? I don't think a
single photon can cause AM noise, because I was talking about single
photon pulses into the photon counting region, not into the analog
region. Please correct me if I'm wrong.
Ilia.
Il 05/05/2016 21:22, Hal Murray ha scritto:
[email protected] said:
Well, in deep space optical comm, we send many photons with a laser, and we
use pulse position modulation at the receiver detecting single photons (or
"few photons"), by which we can send "many bits/photon" (e.g. if you have
256 possible time slots in which the photon can arrive, you have 8 bits/
photon)
Neat. Could you please say a bit more.
What sort of distance? Bandwidth? Error rate?
How big is the laser and telescope? What sort of optics on the receiver?
How hard is it to point the receiver in the right direction? How hard is it
to point the transmitter telescope? ...
How does the receiver get timing?
--
Ilia Platone
via Ferrara 54
47841
Cattolica (RN), Italy
Cell +39 349 1075999
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
