[time-nuts] Microsemi up for sale?

Magnus Danielson magnus at rubidium.dyndns.org
Sun Mar 4 03:21:56 EST 2018


On 03/04/2018 04:04 AM, Richard (Rick) Karlquist wrote:
> When I was working on fiber optic communication test,
> I remember hearing about lasers that were "tuned" with
> variable Peltier coolers.  Power consumption is critical in
> a cesium standard that can run on batteries.  Maybe
> the power consumption of the coolers is a deal breaker.

The peltier elements is needed and nowdays integrated with laserdiodes.
For telecom lasers, which is fully integrated, wavelength shift with
temperature and Peltier elements is needed to temperature-stabilize them
when you run DWDM, which is the telecom scenario which is close, as the
ITU-T channels is 100 GHz apart on a 199 THz base for the 1550 nm window.

So, peltier elements is needed for sure.

However, I wonder if there really is much power involved.


> Rick
> On 3/3/2018 6:18 PM, Hal Murray wrote:
>> Thanks.
>> richard at karlquist.com said:
>>> 2.  Magnetic state selection, as used in the 5071A, would be replaced by
>>> optical pumping.  Len Cutler was heartbroken that HP/Agilent management
>>> wouldn't fund this effort.
>>> It turns out that, even now in 2018, optical pumping is not ready for
>>> prime
>>> time in a working standard because the lasers drift over time.
>> Is there something fundamental in there, or is the lack of products
>> because
>> nobody has made the big investment required to figure out how to do it.
>> What is the bandwidth of the laser?  What happens if it drifts
>> slightly?  Can
>> it be servoed?  ...
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