Doctorate Thesis Defense of Amine BEN SALEM

Thursday September 5^th, 2013 at 10h00, in Amphi II at Sup’Com

Doctorate thesis entitled: 

 Characterization of Photonic Nanowires for Pulse Compression and Sensing Applications

Supervised by

Dr. Rim Cherif & Dr. Mourad Zghal

Thesis Committee 

Abstract: Driven by the potential applications in telecommunications including high bit-rate transmission, pulse compression, multi-wavelength and wavelength division multiplexing (WDM) optical sources, the characterization and design of low loss photonic nanowires with diameters smaller than the wavelength of the guided light are investigated in detail.

Based on the finite element method (FEM), we have proposed a new design of optical waveguide exhibiting high nonlinearities due to their small dimensions and large anomalous velocity dispersion region. Therefore, we have shown that photonic nanowires composed from highly nonlinear glasses of chalcogenide and tellurite, in addition to silica, are suitable waveguides for efficient soliton self-compression with low input pulse energies of sub-nJ level. In fact, based on the implementation of the generalized nonlinear Schrödinger equation (GNLSE), we demonstrate that short fs compressed pulses with few to single optical cycle durations in visible, near- and IR regions could be obtained. Moreover, new designs of mid-IR sources operating beyond 2 μm are proposed which proves that photonic nanowires are suitable waveguides and very promising for mid-IR low-power devices and applications.

By determining the power distribution in the radial direction, we find that a large fraction of the propagating power resides in the evanescent field outside the core physical boundaries which makes photonic nanowires perfect devices for sensing applications. These sensors exploit the fractional power propagating in the evanescent field in order to analyze the specimen’s properties surrounding the waveguide. By inserting photonic nanowires into Mach-Zehnder interferometer (MZI), a highly-sensitive sensor is developed. The proposed MZI-based sensor is found to detect a refractive index change of concentrated solutions as small as 10^-6 refractive index unit (RIU) by assuming only 1-mm-length of sensitive area. This proves that the proposed design is very attractive for compact, flexible, real-time and high sensitive refractometric sensing.

Keywords: Photonic nanowires, nonlinear optics, pulse compression, temporal solitons, supercontinuum generation, optical sensing.