https://doi.org/10.1140/epjb/e2005-00147-x
Optical nonlinearity enhancement of compositionally graded films
Department of Physics, Suzhou University, Suzhou 215006, China
Corresponding author: a lgaophys@pub.sz.jsinfo.net
Received:
25
December
2004
Published online:
30
May
2005
We present a theoretical description for the effective linear and
nonlinear optical properties of compositionally graded films
consisting of nonlinear metal particles and linear dielectric
particles. The volume fraction of metal particles varies along the
direction perpendicular to the film. To account for the
composition gradient, we resort to effective medium approximation
to investigate the equivalent (local) dielectric constant and
third-order nonlinear susceptibility. As a result, the effective
second-rank dielectric constant tensor and fourth-rank nonlinear
optical susceptibility tensor are directly determined by regarding
the graded film as a multilayer one. We predict that for a
power-law composition gradient , the increase of m
leads to large enhancement of the optical nonlinearity and hence
the figure of merit in the high-frequency region. On the other
hand, for a given total volume fraction, we find that the optical
nonlinearity enhancement for the composition gradient case is
larger than the one in non-graded case. Moreover, we can choose
different graded profile to realize the appreciable optical
nonlinearity enhancement. Therefore, the compositionally graded
film can be served as a suitable candidate material for obtaining
the large optical nonlinearity and optimal figure of merit.
PACS: 42.65.-k – Nonlinear optics / 42.79.Ry – Gradient-index (GRIN) devices / 72.20.Ht – High-field and nonlinear effects / 77.84.Lf – Composite materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005