Hi Filip,

Thanks for the swift reply and for recommending the solution. I have tried what 
was suggested in Gib’s post - where a smooth turn on function of around two 
periods should narrow down the linewidth of the source spectrum (or power 
spectrum) - however this does not seem to work for me, 

I have made a sample repo on github to show the issue, I am using a frequency 
of 1.1 and a continuous-src with a 2 period turn on time (I have tried unto 20 
periods turn on and little changes), I would expect the linewidth of this 
source to be approaching zero. I understand that there would be some numerical 
broadening, but still the source is far to broad for me at the moment with a 
width of 0.05, this should be much smaller to simulate a close-to-monochromatic 
light source like an atomic dipole (which a continuous wave src should do).

The field does become more spectrally narrow if I run for a long time (like 
1500 periods), but I expect I should be able to achieve same after 20 periods 
or something, why do the transients take so long to die out.?

The attached repo contains a _test.ctl file with my code and graphs in the 
_test-out/ folder.

https://github.com/eoinmurray/meep-test.git 
<https://github.com/eoinmurray/meep-test.git>

Thanks again for the help.
Eoin

> Begin forwarded message:
> 
> Date: 1 May 2015 20:59:41 BST
> Subject: Re: [Meep-discuss] flux spectrum of continuous source
> From: Filip Dominec <filip.domi...@gmail.com>
> To: Eoin Murray <em...@cam.ac.uk>
> 
> Hi, Eoin,
> everything suggests you have the same problem (which is actually not a
> problem per se) as Gib:
> https://www.mail-archive.com/meep-discuss@ab-initio.mit.edu/msg05374.html 
> <https://www.mail-archive.com/meep-discuss@ab-initio.mit.edu/msg05374.html>
> 
> Regards,
> Filip
> 
> 2015-05-01 14:17 GMT, Eoin Murray <em...@cam.ac.uk <mailto:em...@cam.ac.uk>>:
>> 
>> 
>> Begin forwarded message:
>> 
>> From: Eoin Murray <em...@cam.ac.uk>
>> Subject: flux spectrum of continuous source
>> Date: 1 May 2015 15:14:20 BST
>> To: meep-discuss@ab-initio.mit.edu
>> 
>> I want to create a monochromatic continuous source, in air, and measure the
>> flux through some plane, so I use the following code:
>> 
>>> (set! sources (list
>>>               (make source
>>>                 (src (make continuous-src (wavelength wv) (width 0)))
>>>                 (component Ez)
>>>                 (center 0 0) (size 0 0))))
>> 
>> I thought that the flux spectrum would look like a dirac delta function,
>> instead it is quite broad, why is this?
>> How can I create a continuous wave monochromatic source in meep?
>> Attached are links to the flux spectrum I measured through a plane north of
>> the source, and also an image of the field.
>> 
>> http://i.imgur.com/xeAZCte.png <http://i.imgur.com/xeAZCte.png> 
>> <http://i.imgur.com/xeAZCte.png <http://i.imgur.com/xeAZCte.png>>
>> 
>> http://i.imgur.com/Dza8deC.png <http://i.imgur.com/Dza8deC.png> 
>> <http://i.imgur.com/Dza8deC.png <http://i.imgur.com/Dza8deC.png>>

_______________________________________________
meep-discuss mailing list
meep-discuss@ab-initio.mit.edu
http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss

Reply via email to