[time-nuts] Photodiodes for high frequency OPLL

Attila Kinali attila at kinali.ch
Sat Mar 30 15:50:51 EDT 2013

On Sat, 30 Mar 2013 18:43:03 +0000
David Kirkby <david.kirkby at onetel.net> wrote:

> I would contact Hammamatsu Photonics
> http://www.hamamatsu.com
> 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
> post-doc.

This might be a good idea. Thanks!

> 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.

You mean pulsing the bias voltage at about 7GHz and see whether
i can get a something out of that?

There has been a similar idea around, using a third laser that
is pulsed with the desired offset frequency. Using this and
the non-linear intensity response of the photodiode one can
get a low frequency correlation signal out of the system.
A Japanese group did something like this to acheive offset frequencies
of 160GHz[1] and later of 1THz[2].

In [3] Aljunid describes how to build such a correlator for fs pulses
using a simple LED.

(yes, i came across some really weird stuff when i started digging
into this)

> 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.

Not really. I am mostly looking at stuff i can easily get my hands on.
If possible without using ebay (other should be able to build the
system as well).

			Attila Kinali

[1] "External Synchronization of 160-GHz Optical Beat Signal by Optical
Phase-Locked Loop Technique" by Shigehiro et al, 2006

[2] "Development of an Optical Phase-Locked Loop for 1-THz Optical Beat
Signal Generation" by Shigehiro et al, 2008

[3] "Optical Autocorrelation using Non-Linearity in a Simple Photodiode"
by Aljunid, 2007

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who also happen to be insane and gross.
		-- unknown

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