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    From RichD@21:1/5 to All on Tue Mar 21 15:46:00 2023
    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

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  • From Phil Hobbs@21:1/5 to RichD on Tue Mar 21 19:30:50 2023
    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

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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  • From Joe Gwinn@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Wed Mar 22 11:30:14 2023
    On Tue, 21 Mar 2023 19:30:50 -0400, Phil Hobbs <[email protected]> wrote:

    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.

    It is possible, but extremely difficult to achieve in practice, and
    only national standards labs could do it.

    What Phil H discusses below replaced the above approach overnight. It
    was definitely worth a Nobel Prize. Now, locking light to microwave
    is easy.


    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

    Here is the Nobel Lecture (scroll down):

    .<https://www.nobelprize.org/prizes/physics/2005/hansch/biographical/>


    Joe Gwinn

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