Here's how it basically works: ================================================ MEEP<->reality: --------------- f(MEEP)*c0/a = f(reality) L(MEEP)*a = L(reality) t(MEEP)*a/c0 = t(reality)
with "a meters" in reality being "1" in MEEP ================================================ So in your case: a=100 nm c0 is always the speed of light, so c0=299792458 m/s. But in reality, it doesn't matter what you set it too as is visible here: You want f(reality) = c0/(200nm). So f(MEEP) = f(reality)/(c0/a) = c0/(200nm)/(c0/a) = a/(200nm) = 0.5 Similarly: f(MEEP) = 0.1429 for lambda=700 nm f(MEEP) = 0.2 for lambda=700-200=500 nm f(MEEP) = 0.2222 for lambda=0.5*(700+200)=450 nm f(MEEP) = 0.25 for lambda=400 nm On 20/09/13 14:55, Filip Dominec wrote: > Hi, Rui, > I also always need to compute it from the basics. > > 25 nm corresponds to 0.25 units, therefore one unit corresponds to 1e-7 m, > > 400 nm is roughly 700 THz in reality, therefore you would rescale the > frequency to 700e12 * 1e-7 = 7e7, > but MEEP defines speed of light as 1 instead of 3e8 m/s, so you need > fcen = 7e7/3e8 = 2.5e-1. > > Fwidth should obviously be something similar to fcen in your case. > > Hope this is correct, > Filip > > 2013/9/20, Rui La <larui...@gmail.com>: >> Dear meep users, >> >> I want to get the result from 200nm to 700nm. My structure is a 2D cylinder >> with radius equal to 0.25 in meep and 25nm in reality. How do I set my >> frequency and fwidth? Thank you. >> >> Best, >> >> Rui >> > > _______________________________________________ > meep-discuss mailing list > meep-discuss@ab-initio.mit.edu > http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss >
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