diffractive_chain

Diffractive chain

baptiste Auguié -- 22 June, 2014

In this example we consider a periodic arrangement of ellipsoids along a line, with a separation of the order of the wavelength. The incident light is perpendicular to the chain axis. As the number of particle grows, the signature of diffractive coupling rises from the shadows of the single-particle spectrum.

# dielectric function
wvl <- seq(400, 900)
gold <- epsAu(wvl)

cl <- cluster_chain(N=10, pitch=500)
rgl.ellipsoids(cl$r, cl$sizes, cl$angles, col="gold")
# visualise
rgl.ellipsoids(cl$r, cl$sizes, cl$angles, col="gold")

Influence of the chain length

chain <- function(N, pitch = 500, ...){
  cl <- cluster_chain(N, pitch, ...)
  dispersion_spectrum(cluster = cl, material = gold)
}
  
params <- data.frame(N=c(1, 10, 50))
comparison <- mdply(params, chain)

p <- 
  ggplot(data=comparison)+ facet_wrap(~type, ncol=1, scales="free")+
labs(y=expression(sigma*" /"*nm^2),
       x=expression(wavelength*" /"*nm),
       colour = expression(N), linetype=expression(polarisation))+
  geom_line(aes(wavelength, value/N, linetype=polarisation,
                colour=factor(N),
                group=interaction(N,polarisation)))

p