[time-nuts] Re: Temperature accuracy / repeatability / drift of double ovens

[Bruce Griffiths]

Actually the laser diode current also alters the refractive index of the laser diode chip.
Usually, an external cavity is used to stabilise and tune the diode laser operating wavelength in such applications. A cateye ECDL with a tilt tuned narrow bandwidth filter is easier to construct than either Littrow or Littman-Metcalf EDL's using tilt tuned gratings. 

If the cavity is reanonably compact then a single oven design similar to that used by the E1938A would perhaps be a better choice.
However laser diode temperature controllers usually employ a TEC to cool the diode rather than a heater.

Whilst some FP laser diodes will operate in single transverse and single longitudinal mode without an external cavity and associated band select filter achieving this together with operation at the desired wavelength can be problematic.
I have a single transverse mode, single longitudinal mode FP laser diode that uses a TEC to control the diode temperature along with a low noise current drive. Both the temperature and operating current are selected so that mode hopping doesnt ocurr in temperature and current island of stability.

Bruce  
> On 31/03/2023 11:16 NZDT Gerhard Hoffmann via time-nuts <time-nuts at lists.febo.com> wrote:
> 
>  
> Temperature accuracy / repeatability / drift of double ovens:
> 
> What can be reached here, with a tolerable effort?
> Is there anything known about that in the public? mK-numbers?
> 
> The application is not a crystal oven this time, but diode lasers
> that interrogate Rb atoms and must be kept in lockstep at a certain
> beat frequency. The frequency tuning is mostly by temperature;
> laser diode current plays a minor role, but probably via changing the
> local temperature in the junction and a little bit later in the cavity.
> 
> Are there any GoTo thermistors / circuits for stability?
> 
> Cheers, Gerhard
> (stumbling into new territory)
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