UBC Theses and Dissertations
Finite-Difference Time-Domain (FDTD) simulations and fabrication of a Fabry-Perot cavity using photonic crystal arrays Kim, Jae Hwan (Eric)
In this thesis, Fabry-Perot (FP) cavity structures aimed at a 850nm wavelength are modeled and analyzed by Finite-Difference Time-Domain (FDTD) simulations, for the purpose of fabricating resonant cavity detectors and Vertical-Cavity Surface-Emitting Lasers (VCSELs). The structures are based on square-lattice photonic crystals. In designing a VCSEL, different types of highly reflective mirrors such as GaAs/AlGaAs Distributed Bragg Reflectors (DBRs), and a GaAs-based Sub-Wavelength Grating (SWG) or a Photonic Crystal (Phc) Slab are used to form a FP cavity. FDTD phase analysis is implemented to estimate resonant conditions in a simple but very effective technique. For the fabrication of a resonant cavity detector, square-lattice photonic crystal arrays are written by (1) Focused Ion Beam (FIB) and (2) e-beam lithography, followed by dry-etching. The quality of air holes, etching depths, and sidewalls are scrutinized by Scanning Electron Microscopy (SEM) imaging and Atomic Force Microscopy (AFM). Post-patterning, a sacrificial layer is etched away by Buffered Oxide Etch (BOE) and a suspended photonic crystal membrane is released by Critical Point Drier (CPD). The SWG and Phc slab used as one of the mirrors in the FP cavity structures are beneficial for achieving a compact-sized resonator, as well as forming multi-wavelength arrays, in which the resonance can be widely tuned by lithographically defined parameters (i.e., for the SWG: period and duty factor and for the Phc slab: lattice constant and radius of the air hole).
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