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K. S. Sreelatha
4 Modelling of Nonlinear Waveguide for Optical Soliton
Propagation
The use of solitons as input for nonlinear waveguides is investigated during the doctoral studies of my student. We have modelled waveguides using nonlinear materials
such as ZnO, MgO and T i O 2 with air as upper cladding. We have optimized various parameters like input wavelength, thickness of the waveguide, core nature of the
waveguiding medium and pulse width of the propagating soliton. For a dispersion
free propagation, the pulse width of the input soliton should be compatible with the
thickness of the core [6]. The wide bang gap of the core materials can be utilized
for wavelength and band gap tuning. The refractive index of these materials can be
enhanced by doping them with metals such as gold which will enhance their optical properties too. We used this property to study the propogating modes of high
index materials. These studies will be beneficial to the fields of MEMS and sensing
applications.
4.1 Planar Waveguides
Nonlinear optic materials for integrated nonlinear optics propose stringent problems
as regards their process ability, adaptability and interfacing with other materials.
These additional requirements are intrinsically related to the fabrication of nonlinear
devices, which besides efficiently performing the expected nonlinear operation, must
be miniaturized, compact and should be reliable. The magnitude and speed of the
nonlinearities are essential characteristics in any assessment of the material for NLO
devices.
In recent years, nonlinear optics has grown all over the world into one of the most
important research area. The significance of metallic oxides in the fabrication and
the creation of new materials for industry have resulted in a tremendous increase
of innovative waveguide processing technologies. Currently, this development goes
hand-in-hand with the explosion of scientific and technological breakthroughs in
devices like photonic crystal fibers, and as the root key to the phenomena of Supercontinuum. The tunability as mentioned earlier can put a new dimension to the
concept of such white lasers. Further research is on the thickness of the thin film
waveguide structures which promise to yield innovative results. We concentrated on
the experimental route to fabrication of oxide waveguides for nonlinear applications.
The modelling is done using software Matlab [5, 6].
A thin film planar waveguide consists of three layers of different dielectric materials with the central guiding layer having a refractive index greater than both outer
layers. The upper layer is usually air, an additional layer of dielectric material may
be deposited on top of the thin film, which act as the cladding. The principle of light
confinement is total internal reflection, exactly the same as in an optical fiber. If
a guiding layer with refractive index n 0 and width 2L is sandwiched between two
K. S. Sreelatha
4 Modelling of Nonlinear Waveguide for Optical Soliton
Propagation
The use of solitons as input for nonlinear waveguides is investigated during the doctoral studies of my student. We have modelled waveguides using nonlinear materials
such as ZnO, MgO and T i O 2 with air as upper cladding. We have optimized various parameters like input wavelength, thickness of the waveguide, core nature of the
waveguiding medium and pulse width of the propagating soliton. For a dispersion
free propagation, the pulse width of the input soliton should be compatible with the
thickness of the core [6]. The wide bang gap of the core materials can be utilized
for wavelength and band gap tuning. The refractive index of these materials can be
enhanced by doping them with metals such as gold which will enhance their optical properties too. We used this property to study the propogating modes of high
index materials. These studies will be beneficial to the fields of MEMS and sensing
applications.
4.1 Planar Waveguides
Nonlinear optic materials for integrated nonlinear optics propose stringent problems
as regards their process ability, adaptability and interfacing with other materials.
These additional requirements are intrinsically related to the fabrication of nonlinear
devices, which besides efficiently performing the expected nonlinear operation, must
be miniaturized, compact and should be reliable. The magnitude and speed of the
nonlinearities are essential characteristics in any assessment of the material for NLO
devices.
In recent years, nonlinear optics has grown all over the world into one of the most
important research area. The significance of metallic oxides in the fabrication and
the creation of new materials for industry have resulted in a tremendous increase
of innovative waveguide processing technologies. Currently, this development goes
hand-in-hand with the explosion of scientific and technological breakthroughs in
devices like photonic crystal fibers, and as the root key to the phenomena of Supercontinuum. The tunability as mentioned earlier can put a new dimension to the
concept of such white lasers. Further research is on the thickness of the thin film
waveguide structures which promise to yield innovative results. We concentrated on
the experimental route to fabrication of oxide waveguides for nonlinear applications.
The modelling is done using software Matlab [5, 6].
A thin film planar waveguide consists of three layers of different dielectric materials with the central guiding layer having a refractive index greater than both outer
layers. The upper layer is usually air, an additional layer of dielectric material may
be deposited on top of the thin film, which act as the cladding. The principle of light
confinement is total internal reflection, exactly the same as in an optical fiber. If
a guiding layer with refractive index n 0 and width 2L is sandwiched between two