Say you want to generate a very narrow light
band in the UV, with precise desired frequency.
Is it feasible to do so, by starting with a reference
microwave signal, then heterodyning up and up,
doubling in successive stages?
What is the limit on this process? Assume each
stage utilizes a technology appropriate for that wavelength.
--
Rich
On 2023-03-21 18:46, RichD wrote:
Say you want to generate a very narrow light
band in the UV, with precise desired frequency.
Is it feasible to do so, by starting with a reference
microwave signal, then heterodyning up and up,
doubling in successive stages?
What is the limit on this process? Assume each
stage utilizes a technology appropriate for that wavelength.
Rich
You actually go the other way, starting with a femtosecond Ti:sapphire
laser, pushing it through a holey fiber to broaden the spectrum by self
phase modulation, and then lock a line at the blue end to the second
harmonic of the red end.
It's a 1:1 lock, so there's no phase ambiguity. You can lock the beat
frequency to an RF signal, and get e.g. x10**6 frequency multiplication >without the accompanying 120 dB phase noise penalty.
Jan Hall and Ted Haensch got the Nobel prize in physics for that bit of >extreme cleverness.
Cheers
Phil Hobbs
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