Re: OT: Atomic nucleus excited with laser: a breakthrough after decades

Joe Gwinn <joegwinn@comcast.net> wrote:

On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
 
[snip]
 

The cleverest part of the Hall-Haensch comb generator is that you can lock
the blue end of the comb to the second harmonic of the red end, one tooth
off, and lock the difference to a good reference. Then all the teeth have
the same phase noise as the reference oscillator, rather than 20 log(600
THz /  100 MHz) ~ 138 dB worse, as it would be in a multiplier. 

 
Hmm.  It had to be true, but I never connected the dots there.  What
is mechanism by which this is achieved?  References?
 
Thanks,
 
Joe Gwinn
 

>
Don’t have the reference handy, but the basic idea is to use a modelocked
system Ti:sapphire laser at 750 nm to generate ~100-fs pulses, then use
fiber/grating pulse compression to bring that down to a few femtoseconds,
followed by a holey fiber to broaden the spectrum to more than an octave.
>
Jan Hall is one of the best instruments guys ever.