[Meep-discuss] Question about units in the Material Dispersion page on the MEEP ab-initio website

[Eric Smoll]

Hello all,

I have searched the archives and read through all the material on the
website but am still unsatisfied with my understanding of units on the
Material Dispersion
page.

http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial/Material_dispersion

I know from the archives that omega and gamma are to be specified in units
of 2*pi*c/a.  But I find the two equations given for the relative
dielectric constant to be extremely confusing and inconsistent.

What are the units of the numbers given in the first E-polarizations
entry?
(omega 1.1)(gamma 1e-5)(sigma 0.5)
2*pi*c/a, 2*pi*c/a, and a unitless fraction, correct?
How is that consistent with the equation
epsilon(f) = 2.25 + ( (1.1^2)*0.5 ) / ( (1.1^2) - (f^2) - i*f*(1e-5)/(2*pi)
)

I would greatly appreciate anyone who can help me clarify this.

Thanks
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[Meep-discuss] custom-src: python-meep or C++

[Eric Smoll]

Is numpy/python-meep competitive with the the C++ Meep interface
for very long simulations with interpolated discrete custom source
functions.

Best,
Eric
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Re: [Meep-discuss] custom-src: python-meep or C++

[Eric Smoll]

Can one define a source function with interpolated discrete data with
inline C/C++ when using
python-meep in the same way it is used to speed the definition a material
function?

-Eric
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[Meep-discuss] C++ polarizations

[Eric Smoll]

Hello Meep users,

In a thread titled: using perfect metal in C++ interface (
http://www.mail-archive.com/meep-discuss@ab-initio.mit.edu/msg01997.html)
Professor Johnson clarified that one controls the spatial location of the
polarizability with sigma.  However, both Renaud Vallee (
http://www.mail-archive.com/meep-discuss@ab-initio.mit.edu/msg03271.html)
and Bin Huang (
http://www.mail-archive.com/meep-discuss@ab-initio.mit.edu/msg03784.html)
have run into problems trying to implement multiple polarizations to
describe a metal.  I do not see a problem with Renaud's approach.  Is he
declaring his sigma functions appropriately?  To specify multiple
polarizations, is Renaud correct in applying the add_polarizability method
to a structure object twice with different parameters?

Best,
Eric
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[Meep-discuss] Spatial coordinates associated with discrete output from a specified volume

[Eric Smoll]

I would like to know the spatial coordinates of each point in an an output
volume (a line, for example).
Can I get meep to output the spatial coordinates of each point?  This would
be excellent.
If not, can anyone explain how meep compute the coordinates that it chooses
to output so I can do it myself?
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Re: [Meep-discuss] Question

[Eric Smoll]

Responding to my own question: The code below (posted on a forum somewhere)
works on MEEP version 1.1.1.

(reset-meep)
(set! dimensions 2)
(set! force-complex-fields? true)
(set! geometry-lattice (make lattice (size 12 12 no-size) )) ;
computational domain
(set! sources (list (make source (src (make continuous-src (frequency
1.0))) (center 0.0 0.0) (component Ez) ))) ; line current source along
z-direction located at the center of the computational domain
(set! pml-layers (list (make pml (thickness 2.0) ))) ; PML layers in all
direction
(set! resolution 40.0)
(init-fields)
(meep-fields-solve-cw fields 0.0001 1 10)
(use-output-directory)
(output-efield-x) ; x-comp of E-field
(output-efield-y) ; y-comp of E-field
(output-efield-z) ; z-comp of E-field
(output-hfield-x) ; x-comp of H-field
(output-hfield-y) ; y-comp of H-field
(output-hfield-z) ; z-comp of H-field

Is this a bug? It will not work on my version of MEEP 1.2.1.
meep-fields-solve-cw is quite useful.  Can this tool be repaired?

On Thu, Jun 6, 2013 at 6:27 PM, Eric Smoll ericsm...@gmail.com wrote:

 Does the meep-fields-solve-cw function simply not work?

 I have tried inserting it into tutorial examples (using init-fields and
 force-complex-fields, with and without arguments after fields) with no
 success.  Is there a working example anywhere?

 -Eric



ericsmoll2...@u.northwestern.edu
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[Meep-discuss] Far-field spectra with meep-fields-solve-cw

[Eric Smoll]

Hello MEEP users,

I know that you can use the flux-region tool in an FDTD simulation to find
far field measurements of absorption, scattering, and extinction. As far as
I understand, I should be able to compute these quantities using the field
amplitudes given by meep-fields-solve-cw and the equation shown on the
introduction page of the website (
http://ab-initio.mit.edu/wiki/index.php/Meep_Introduction#Transmission.2Freflection_spectra)
for the integral of the Poynting vector. Is this correct? Is there a better
way to translate meep-fields-solve-cw output to far field absorption,
scattering, and extinction values?

-Eric
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