Path: ...!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Phil Hobbs Newsgroups: sci.electronics.design Subject: Re: OT: Atomic nucleus excited with laser: a breakthrough after decades Date: Wed, 8 May 2024 23:35:19 -0000 (UTC) Organization: A noiseless patient Spider Lines: 34 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Thu, 09 May 2024 01:35:19 +0200 (CEST) Injection-Info: dont-email.me; posting-host="e32ac61c3fa108018fad465cdface15e"; logging-data="268101"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+NheXPxs0oIt+mahE0gJhp" User-Agent: NewsTap/5.5 (iPhone/iPod Touch) Cancel-Lock: sha1:YxiCKUS7q6Qh1q5Vz5eKXso6V+Q= sha1:WB69nBfMwcpdzzBVgHimvSrPxVU= Bytes: 2601 Joe Gwinn wrote: > On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs > 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. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics