{"id":363312,"date":"2024-04-20T14:01:08","date_gmt":"2024-04-20T14:01:08","guid":{"rendered":"\/forum\/forums\/topic\/how-to-calculate-scattering-power\/"},"modified":"2024-04-20T14:01:08","modified_gmt":"2024-04-20T14:01:08","slug":"how-to-calculate-scattering-power","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-to-calculate-scattering-power\/","title":{"rendered":"How to calculate scattering power?"},"content":{"rendered":"

Why does Lumerical example(defect scattering<\/strong>) use the difference of two cone volume integrals to obtain the scattered power in the PSL.lsf script?<\/p>\n

the model:<\/p>\n

\"\"<\/p>\n

 <\/p>\n

Here is the script: <\/p>\n

############################################<\/p>\n

# file: psl_analysis<\/p>\n

# Description: This file is used to calculate<\/p>\n

# the scattering from PSL spheres. It runs<\/p>\n

# a reference simulation as well as the defect<\/p>\n

# simulations.<\/p>\n

# After the simulations are complete, the far<\/p>\n

# fields are calculated. The reference far field<\/p>\n

# is subtracted from the defect far field,<\/p>\n

# giving the scattered far field.<\/p>\n

#<\/p>\n

# Copyright 2010 Lumerical Solutions Inc<\/p>\n

############################################<\/p>\n

 <\/p>\n

polarization = “P”; #sets which polarization to run: “P”, “S”, “C” (circular)<\/p>\n

 <\/p>\n

run_simulations = 1; # set to 0 to analyze previously run simulations<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

if (run_simulations) {<\/p>\n

switchtolayout;<\/p>\n

 <\/p>\n

if (polarization==”P”) {<\/p>\n

setnamed(“FDTD”,”x”,1e-6);<\/p>\n

setnamed(“source1″,”polarization angle”,0);<\/p>\n

setnamed(“source1″,”angle theta”,70);<\/p>\n

setnamed(“FDTD”,”y min bc”,”Symmetric”);<\/p>\n

select(“source2”);<\/p>\n

delete;<\/p>\n

}<\/p>\n

if (polarization==”S”) {<\/p>\n

setnamed(“FDTD”,”x”,1e-6);<\/p>\n

setnamed(“source1″,”polarization angle”,90);<\/p>\n

setnamed(“source1″,”angle theta”,70);<\/p>\n

setnamed(“FDTD”,”y min bc”,”Anti-Symmetric”);<\/p>\n

select(“source2”);<\/p>\n

delete;<\/p>\n

}<\/p>\n

if (polarization==”C”) {<\/p>\n

setnamed(“FDTD”,”x”,1e-6);<\/p>\n

select(“source2”);<\/p>\n

delete;<\/p>\n

setnamed(“source1″,”polarization angle”,0);<\/p>\n

setnamed(“source1″,”angle theta”,0);<\/p>\n

setnamed(“FDTD”,”x”,0);<\/p>\n

select(“source1”);<\/p>\n

copy;<\/p>\n

set(“name”,”source2″);<\/p>\n

set(“polarization angle”,90);<\/p>\n

set(“phase”,90);<\/p>\n

setnamed(“FDTD”,”y min bc”,”PML”);<\/p>\n

}<\/p>\n

 <\/p>\n

runsweep;<\/p>\n

save;<\/p>\n

}<\/p>\n

 <\/p>\n

swp=”sweep_rad”;<\/p>\n

farfieldfilter(0.5);<\/p>\n

 <\/p>\n

# get the data from the sweep<\/p>\n

E2_far=getsweepresult(swp,”E2_far”);<\/p>\n

T=getsweepresult(swp,”T”);<\/p>\n

SP=getsweepresult(swp,”SP”);<\/p>\n

rad = E2_far.rad;<\/p>\n

res = length(E2_far.ux);<\/p>\n

E2=E2_far.E2_far;<\/p>\n

#plot(rad*1e9,log10(T.T*SP.SP),”radius (nm)”,”scattered power (log10, Watts)”<\/p>\n

scat_power=matrix(length(rad)); #\u521b\u5efa\u77e9\u9635\u5b58\u50a8\u4e0d\u540c\u534a\u5f84\u7684scat_power<\/p>\n

 <\/p>\n

for (i=1:length(rad)) {<\/p>\n

 <\/p>\n

P_far_scat = sqrt(eps0\/mu0) * pinch(E2(1:res,1:res,i));<\/p>\n

scat_power(i) = 0.5*(farfield3dintegrate(P_far_scat,E2_far.ux,E2_far.uy,72,0,0)-farfield3dintegrate(P_far_scat,E2_far.ux,E2_far.uy,25,0,0));<\/p>\n

image(E2_far.ux,E2_far.uy,pinch(P_far_scat)\/pinch(max(P_far_scat)),”ux”,”uy”,”far field”,”plot polar”);<\/p>\n

}<\/p>\n

 <\/p>\n

savedata(“psl_”+polarization,scat_power); # save data to an ldf file<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

# plot results from P,S,C polarization on same plot (if results exist)<\/p>\n

if (fileexists(“psl_p.ldf”)) { loaddata(“psl_P”); spP = scat_power; } else { spP = 0; }<\/p>\n

if (fileexists(“psl_s.ldf”)) { loaddata(“psl_S”); spS = scat_power; } else { spS = 0; }<\/p>\n

if (fileexists(“psl_c.ldf”)) { loaddata(“psl_C”); spC = scat_power; } else { spC = 0; }<\/p>\n

 <\/p>\n

if (spP==0 ) {spP=0*rad; }<\/p>\n

if (spS==0 ) {spS=0*rad; }<\/p>\n

if (spC==0 ) {spC=0*rad; }<\/p>\n

 <\/p>\n

plot(2*rad(1:length(rad))*1e9,log10(spP),log10(spS),log10(spC),”Diameter (nm)”,”log10(scattered power)”);<\/p>\n

legend(“P”,”S”,”Circular”);<\/p>\n

My problem: <\/strong><\/p>\n

scat_power(i) = 0.5*(farfield3dintegrate(P_far_scat,E2_far.ux,E2_far.uy,72,0,0)-farfield3dintegrate(P_far_scat,E2_far.ux,E2_far.uy,25,0,0));<\/p>\n

Why does it use the power with a half-angle of 72 degrees minus the power with a half-angle of 25 degrees? How are the values of 72 and 25 determined?<\/p>\n","protected":false},"template":"","class_list":["post-363312","topic","type-topic","status-closed","hentry","topic-tag-2dmaterialsandmetals-1","topic-tag-TFSF-1","topic-tag-3DFDTD-1","topic-tag-metal","topic-tag-scattered-field-1","topic-tag-scattering"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t