What is an 'FRK'? Thanks,
Dana On Sat, Jun 9, 2018 at 7:51 AM, ew via time-nuts <time-nuts@febo.com> wrote: > Having followed the conversation and having looked at the p[possibility > using a FRK with laser diode, it is low on our list because of all the > ongoing projects but please if you want to spend time and money use any > thing but a FE5680. I was one of the first using it and noticed and posted > a 4 Hz constant deviation using my Tracor 527 E subsequent confirmed by the > attached. Do not have info as to who posted it. > Using a FRK is the easiest way to do so if interested contact me off list, > based on our tests is a close second to the HP 5065A. > Bert Kehren > > In a message dated 6/9/2018 7:23:45 AM Eastern Standard Time, > bruce.griffi...@xtra.co.nz writes: > > > Theres also > > http://www.photonics.philips.com/application-areas/sensing/components > > and > > https://www.sacher-laser.com/home/industriallasers/point_ > and_line_laser_module/industrial_laser_modules/micron_laser.html > Bruce > > On 09 June 2018 at 20:54 mimitech mimitech <mimit...@gmail.com> wrote: > > > > > > Thanks Attila for your suggestion. > > > > I prefer the 780/795nm VCSEL scheme for its simplicity. After some > > searching, looks like the 780nm VCSELs are also not easy to source, > > although other types of 780nm LD are common. > > > > I have purchased small amount of Vixar P/N “795S-0000-BC01” 795nm single > > mode VCSEL from a local distributor, price is about $500/pcs. I'm not > sure > > whether this model could work in CPT rubidium clock. > > > > A more suitable model maybe Oclaro P/N “APM2101013300” 795nm single mode > > VCSEL, with unit price $800, which was proved to work as this paper > > "A compact atomic magnetometer for cubesats", > > https://open.bu.edu/bitstream/handle/2144/16303/Knechtel_bu_ > 0017N_11402.pdf > > , > > > > this thesis "Ultra-Low Phase Noise Atomic Clock using Coherent Population > > Trapping (CPT) in Rubidium" > > http://etheses.whiterose.ac.uk/20073/1/Burtichelov_PhD_ > Thesis_with_papers_V7.pdf > > > > and also it was used in commercial CPT rubidium clock - Microsemi SA.3xm > > series. The cheapest model is SA.31m priced about $1100 at Digikey / > > Mouser. > > > > Another paper "VCSEL Laser System for Atomic Clocks" > > http://ixnovi.people.wm.edu/documents/NathanBelcherREUPaper.pdf test > > several VCSEL from different vendors and found the ULM 794.7 nm single > mode > > VCSEL can work. > > > > Thanks. > > > > mimitech. > > > > > > On Tue, 5 Jun 2018 11:11:59 +0200, Attila Kinali <att...@kinali.ch> > wrote: > > > > > > On Mon, 4 Jun 2018 21:31:56 +0800 > > > mimitech mimitech <mimit...@gmail.com> wrote: > > > > > > > I'm planning to build a CPT (coherent-population-trapping) rubidium > > clock > > > > as my next hobby project. The main purpose is to learn the principles > > > > behind CPT rubidium clock, and hopefully got similar or better > > performance > > > > than commercial miniature rubidium clock such as FE-5680A. > > > > > > Building a CPT clock is slightly more involved than you might think > > > at first. The laser diode is only one part of it. You will most likely > > > be able to improve on the short-term stability of the FE-5680 (which > > > is rather poor). But I doubt you will be able to improve much on > > > the long term stability, which is where things actually become > > interesting, > > > if you use a naive approach. > > > > > > Nevertheless, I have not seen many 794/795nm diodes around. The only > > > one that I have the datasheet of is the one from Vixar. > > > You might want want to consider going for the D2 line instead of the > > > D1 line, as 780nm diodes are more commonly available than 795nm. You > will > > > also need to buy several of those and select the ones that come closest > > > to the wavelength at the desired opearating conditions (usuall spread > > > is +/-1nm to +/-10nm). Do not assume you can tune more than 0.1nm with > > > temperature and current (rule of thumb is that you get about 10GHz > > > per °C and mA). If you need more tuning range, you will need to add an > > > external cavity (can give you up to 5nm range), which then needs to be > > > tuned to the 3.45GHz (ie it's length needs to be approximately 8-9cm). > > > > > > Alternatively, you can get two S1-0780-XXX from Sacher Laser > > > (cost IIRC 2500€ each) and keep them 6.9GHz apart (using an optical > PLL). > > > If you have enough money to spend, I'd go for two Cateye diode laser > CEL's > > > from Moglabs (cost AFAIK 5000€ each) > > > > > > No matter what you choose, you will need some wavelength stabilization > > > scheme. You can either do that with the vapor cell itself or use > > > an additional cell and do a DVALL or a saturated absorption locking. > > > Note that this addtional cell will need to be without buffer gas. > > > An external cell will offer better stability and thus lower noise, > > > which directly translates into higher stability. > > > > > > As polarisation scheme, I suggest using σ+/σ- as it seems to be more > > > robust than the lin/lin schemes. > > > > > > Attila Kinali > > > -- > > > It is upon moral qualities that a society is ultimately founded. All > > > the prosperity and technological sophistication in the world is of no > > > use without that foundation. > > > -- Miss Matheson, The Diamond Age, Neil Stephenson > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.