Etude des propriétés physiques dans les cristaux magnéto photoniques

Abstract

This thesis is essentially dedicated to the study of physical properties in magneto-photonic crystals. The aim is to optimize a two-dimensional magneto-photonic crystal slab waveguide structure for producing a sensitive magnetic field sensor. We used two simulation software's that are perfectly suited to the study of structures based on magneto-photonic crystals. BandSOLVE uses the plane wave method (PWE) and BeamPPROP using the beam propagation method (BPM). We studied two types of structures: (Bi:YIG/SiO2) and (BIG/GGG), whose materials are bismuth iron garnet BIG and bismuth substituted yttrium iron garnet Bi:YIG which have very interesting magneto-optical properties. A kind of magnetic field sensor (MFS) using a two-dimensional (2D) magnetic photonic crystal (MPC) slab waveguide as the sensing structure is proposed and investigated numerically. The slab structure is based on bismuth iron garnet (BIG), a well-known magnetic material with effective magneto-optical (MO) properties, sandwiched with gadolinium gallium garnet (GGG) as substrate. The complete photonic band gap (PBG) of the 2D MPC is simulated and optimized for realization of polarization-independent waveguides. The simulation results show that the width and position of the complete PBG depend on the thickness of the BIG slab and the radius of the air holes used in the design. By reducing the lightwave propagation losses and enhancing the mode conversion ratio, increased sensitivity is obtained. Based on the Faraday effect, a good linear relationship is observed between the normalized output light intensity and the magnetic field strength as the gyrotropy parameter g is varied from 0.13 to 0.19, a g-range used as the sensor dynamic range. The remarkable enhancement in sensing performance due to the MO effect makes the designed device suitable for magnetic field sensing. The results are discussed to provide a basis for investigation of 2D MPC slab waveguides based on the same structure, which are of particular interest for development of highly sensitive MFSs.