Download (4Mb) - Etheses - Saurashtra University

Chapter I Brief Introduction...
would be modulated by domains, whereas those associated with even-rank
tensor remain constants. This makes the crystal different from a
homogeneous single domain one and, specially, suitable for nonlinear
photonics applications. In case of wave length of light wave comparable with
or smaller than the size of domain, i.e., the reciprocal vector of the modulated
structure is comparable or larger than the wave vector of light wave, many
novel effects may be created through the interaction of the wave vectors and
reciprocal vectors of super-lattice, for instance, the enhancement of optical
frequency conversion, the amplification of light scattering signal, the
generation of entangled photon pair and polariton excitation etc. The interest
in engineering domain structure of ferroelectric crystal also lie in applying to
novel devices matched with contemporary nonlinear photonics, laser and
quantum dots [106].
One interesting phenomenon of optics is the slow light, which is the
propagation of an optical pulse or other modulations of an optical carrier at
low group velocity. This term is applied when the velocity is at least 100 times
slower than the speed of light in vacuum. Recently, Monat et at [107]
reviewed advances related to slow light in periodic structures, where the
refractive index varies along one or two directions, i.e., gratings and planar
photonic crystals. The recent nonlinear experiment performed in photonic
crystal waveguides, which demonstrate the strong reinforcement of nonlinear
third order optical phenomenon with slow light. They have discussed the
challenges associated with slow light in 2-D structures and their unique
advantage in dispersion engineering for creating a broadband nonlinear
device for all optical processing. By breaking down the relation between
33