On Mon, 01 Apr 2013 22:32:11 +1300 Bruce Griffiths <[email protected]> wrote:
> Attila Kinali wrote: > > On Mon, 01 Apr 2013 09:08:51 +1300 > > Bruce Griffiths<[email protected]> wrote: > > > > > >> Nothing to do with laser line width. > >> Merely indicating that the photodiode mixer can be used with a suitable > >> LO to build an optical spectrum analyser front end. > >> > > Are you refering to heterodyne spectrum analyser? > > > Essentially, however if the photdiode has say a 1GHz bandwidth the LO > could be stepped in say 1GHz steps with subsequent circuitry providing > finer resolution. The difficulty here is to get an LO laser that can be stepped in 1GHz steps and keep it there, stable. The only way i have seen sofar is using a mode locked laser and referencing/stabilizing the LO to one of the comb tooths. Technically seems to be relatively simple, but unfortunately a mode locked laser is financially out of the reach of a mere mortal. > Constructing an optoelectronic version of either an LSB or USB converter > may be interesting. Yes, an optoelectronical I/Q mixer would be very intersting. But also very difficult and fragile to build, considering that you have to keep the distances stable down to a couple of 10nm. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown _______________________________________________ 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.
