# Knowledge Base

 sourceintensity We've made some changes. Use 'Ctrl-F5' to clear your browser cache.

Returns the source power divided by the area of the source. In 3D simulations, the units will be in Watts/m2 if CW norm is used, and Watts/m2/Hertz2 if No norm is used. This function is often used when normalizing power measurements from simulations with a TFSF source.

In the case of multiple sources, the sourceintensity(f) command will return the sum of all sourceintensity from all sources.

 Supported Product: FDTD, MODE

 Syntax Description out = sourceintensity(f); Returns the source intensity at the vector of frequency points f (f is the frequency in Hz). out = sourceintensity(f, option); The additional argument, option, can have a value of 1 or 2. If it is 2, the data is unfolded where possible according to the symmetry or anti-symmetric boundaries if it comes from a monitor that intersect such a boundary at x min, y min or z min. The default value of option is 2. out = sourceintensity(f, option, name); This function makes it possible to perform the normalization using the spectrum of one source, rather than the sum of all the sources.

Examples

This example shows how to use the transmission, sourcepower and sourceintensity functions to measure the power injected by a TFSF source. Notice that the monitor is 1/4 the area of the source.

newproject;          # create new simulation

save("test");

set("mesh accuracy",4);

set("x span",2.5e-6);

set("y span",2.5e-6);

set("z span",2.5e-6);

set("x span",2e-6);

set("y span",2e-6);

set("z span",2e-6);

set("wavelength span",0);

addpower;         # add monitor (1/4 area of source)

set("x span",1e-6);

set("y span",1e-6);

run;            # run simulation

m="monitor";

f=getdata(m,"f");     # get frequency vector

T=transmission(m);     # get power transmission (fraction of source power)

sp=sourcepower(f);     # get power injected by source (Watts)

I=sourceintensity(f);   # get source intensity (Watts/m^2)

area = getdata("source","area"); # get source area (it's not exactly 2um^2 due to finite sized mesh)

# output results

?"Transmitted power (fraction of source power): " +num2str(T);

?"Transmitted power (Watts): " +num2str(T*sp);

?"Source power (Watts): "+num2str(sp);

?"Source intensity (Watts/um^2): " + num2str(I*1e-12);

?"Ensure Intensity*Area=Power: " + num2str(I*area/sp);

> Transmitted power (fraction of source power): 0.235078

> Transmitted power (Watts): 1.24415e-015

> Source power (Watts): 5.2925e-015

> Source intensity (Watts/um^2): 1.30714e-015

> Ensure Intensity*Area=Power: 1