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Science Forum Index » Optics Forum » balanced photodiode and..
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| sperelat |
 Posted: Fri Apr 25, 2008 8:02 pm |
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To detect squeezed vacuum, I need to do homodyne detection.
For that, I have two choices.
One is using Balanced photodiode, and the other is using two PD and
splitter/combiner.
I'm not sure if ordinary op-amp circuit can work ,.
If you make Balanced photodiode, how do you get its bandwidth
experimentally?
For splitter/combiner, I have never used it.
Can it function as a subtractor and adder for two signals?
Can I switch between two modes?
What is its bandwidth? can it cover from a few hundred Hz to several
MHz? |
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| Jürgen Appel |
| Posted: Sat Apr 26, 2008 6:10 am |
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sperelat schrieb:
Quote: To detect squeezed vacuum, I need to do homodyne detection.
For that, I have two choices.
One is using Balanced photodiode, and the other is using two PD and
splitter/combiner.
I'm not sure if ordinary op-amp circuit can work ,.
Both work, what is best depends on many more details of your setup (pulsed/
cw , high LO power/high sensitivity, bandwidth, pulse rate, amount of
unbalancing that the detector has to take, ...).
Get Phil Hobb's book, there you will find plenty of valuable information and
also circuit diagrams that even might work without any changes.
Quote: If you make Balanced photodiode, how do you get its bandwidth
experimentally?
Shot noise is white noise. Therefore the shot noise spectrum shows your
detector bandwidth.
Quote: For splitter/combiner, I have never used it.
Can it function as a subtractor and adder for two signals?
Can I switch between two modes?
Yes and yes.
What is its bandwidth? can it cover from a few hundred Hz to several
MHz?
I would not use a heterodyne junction below at least a few MHz. If you want
to look at low sideband frequencies, go for the back-to-back diodes in a
transimpedance setup.
Cheers,
Jürgen
--
GPG key:
http://pgp.mit.edu:11371/pks/lookup?search=J%FCrgen+Appel&op=get |
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