Hanoch Lev-Ari, Nicol E. McGruer, Charles A. DiMarzio
Date of Award
Master of Science
Department or Academic Unit
College of Engineering, Department of Electrical and Computer Engineering
electrical engineering, anti-crossing, asymmetric waveguide, FDTD, mode coupling, photonic crystals, PWE
Electrical and Computer Engineering | Engineering
Planar photonic microstructures in optically thin silicon membranes are becoming increasingly favored in emerging optical signal processing and sensing technologies. Two-dimensional photonic crystals slabs (2-D PC slabs) are especially interesting due to their ability to confine and manipulate light on small scales by a combination of photonic bandgap and index guiding. Line-defects defined in the otherwise periodic lattices are served as waveguides, and point-defects are used as miniaturized optical resonators.
The traditional photonic devices on a broad photonic bandgap which exists in dielectric membranes only for the transverse electric (TE) polarized light, restricting their operation to that particular polarization. Thus, the capabilities of photonic circuits can be significantly enhanced if both polarization modes are utilized. While independent manipulation of TE- and TM-polarized light in photonic crystal membrane has been demonstrated, polarization mixing between different polarization states has not been thoroughly investigated. This thesis explores polarization cross coupling between the quasi-orthogonal modes triggered by structural asymmetries in the guiding and localization regimes. The criteria for coupling are established by parity arguments applied to the field overlap integral. Two basic device geometries representing the fundamental building blocks of many existing photonic circuits, viz. (i) a photonic crystal line-defect waveguide and (ii) a photonic crystal mode-edge cavity, are studied computationally and experimentally. Polarization cross coupling between the TE- and TM-like modes in photonic crystal membranes is utilized in the development and demonstration of novel narrow-band grating filters and vertical add-drop cavity filter.
Liu, Zao, "Polarization cross coupling in asymmetric photonic waveguides" (2010). Electrical and Computer Engineering Master's Theses. Paper 40. http://hdl.handle.net/2047/d20000935
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