AUTHOR=Sotto Moïse , Tomita Isao , Debnath Kapil , Saito Shinichi 

TITLE=Polarization Rotation and Mode Splitting in Photonic Crystal Line-Defect Waveguides

JOURNAL=Frontiers in Physics

VOLUME=Volume 6 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2018.00085

DOI=10.3389/fphy.2018.00085

ISSN=2296-424X

ABSTRACT=In a line-defect waveguide of a planer photonic crystal (PhC), we found a new rotational state of polarised light, which exhibits `polarisation rotation' on the PhC plane, when a phase mismatch $m$ was added to the air-hole alignment of the waveguide, where mode splitting was simultaneously observed in the dispersion curve. To account for the polarisation rotation together with the mode splitting, we propose a two-state model that is constructed from Schr{\"o}dinger equation obtained from the equation for electromagnetic waves.  The proposed two-state model gives an explanation on the relation between the polarisation-rotational angle $\theta$ and the mismatch $m$ and on its rotational direction (i.e., clockwise or anticlockwise direction) that depends on the mode.  Using the two-state model, we also discuss the angular momenta of the polarised light in the PhC waveguide, which are directly related to the Stokes parameters that characterise the polarisation rotations.