[time-nuts] Photodiodes for high frequency OPLL

David Kirkby david.kirkby at onetel.net
Sat Mar 30 14:43:03 EDT 2013

On 30 March 2013 11:48, Attila Kinali <attila at kinali.ch> wrote:
> Moin,
> I'm currently reading up some stuff on optical PLLs and am stuck with some
> details i cannot find any data on.
> The goal is to make two lasers locked with about 7GHz of offset to eachother.
> So far, i figured out that PIN photodiodes can go up to several 100MHz
> transition frequency and avalanche photodiodes are available up to 2GHz.

I would contact Hammamatsu Photonics


and see if they can help. They might havae something in development,
that is not on the web site. If you are in a uni, they might be
especially helpful - they paid my salary for a couple of years as a

I played tricks during my Ph.D. of gain-modulating an APD with a step
recovery diode. I was wondering if there is anything one could do to
gain modulate one at 7 GHz, but I can't think how one could achieve
anything useful by changing the gain, but it might be worth thinking
about. I'm just trying to "think out of the box" - I can't actually
see how it would help.

Have you considered using a photomultiplier tube? I think there are
some fast PMTs around, though perhaps not fast enough. 20 years I used
to know what was state of the art in this area, but not any more.


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