On Wed, 11 Oct 2006, João Luis Silva wrote:
the nonlinear coefficient n2 in um^2/W as described on the web page. My
length unit is the um, so all is OK so far. My question is what are the
units of the electric field, so I know what to pass to the (amplitude A0)
of the gaussian-src. Assuming I=(1/2) epson0 c n |E|^2, the documentation
That's not really a useful to phrase the question, because the amount of
field you get from a given current depends on the geometry as well as on
the current amplitude.
A better way to think of it is this: the units of field and power are
arbitrary, and the units of n2 are arbitrary. The only meaningful
quantity is the product of n2 * power. So, you are free to *choose* the
units of n2 as um^2/W, and then you can choose to think of the power as
being in units of Watts.
Suppose you want to input 5W of power into a waveguide (or whatever).
What you should do is to put a source with some amplitude "A" and measure
the power P that you get in your waveguide (using one of Meep's flux
functions). Then to make the power 5, you should scale A by sqrt(5/P).
Steven
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