By adding a point defect to a photonic crystal structure, a microcavity can be made to trap electromagnetic energy with wavelength inside the photonic bandgap (PBG). This property together with other unique properties of photonic crystals enables us to control the propagation and spectrum of transmitted wave inside the photonic crystal waveguiding structures and to design and implement microscale optical filters. In this paper we focus on the design of notch filters in photonic crystal waveguides based on the coupling of waveguide and cavity. We discuss about the properties of a single cavity and its necessary modifications to achieve efficient coupling between cavity and waveguide and eventually obtain desired notch filters at the frequency range of interest. We also discuss the coupling of multi-cavities to a waveguide and the possibility of attaining filters with better performances is presented, and the spectrum and lineshapes of the resulting filters are characterized.
A method for controlling the dispersion and thus group velocity of guided modes in photonic crystal (PC) waveguides using bi- and quasi-periodic lattices is presented. Rectangular lattice photonic crystals are proposed as possible candidates for implementing such control. However, these structures, and generally all bi-periodic lattices, develop undesirable characteristics as the perfect square lattice is perturbed. Thus, quasi-periodic photonic crystals, which have been shown to be promising in selective mode engineering, were examined next. A possible scheme for engineering of a single mode PC waveguide with guiding through the entire bandgap is presented.
We present a systematic method for designing electromagnetic modes in dielectric-core photonic crystal optical waveguides. We show that the guided modes of the photonic crystal waveguides are mainly confined to the guiding region. The properties of these modes can be modified by changing the geometry of the air holes next to the guiding region. We show how this concept can be used to design single-mode photonic crystal waveguides. We also describe a method for changing the slope of the dispersion diagrams of these guided modes.
We have developed a new method for the fabrication of monolithic AlGaAs microlenses on the surface of GaAs/AlGaAs light emitting diodes by combing crystal growth, ion etching and steam oxidation with wet chemical removal of the oxide. Control over the precise processing parameters has resulted in the precise control over the shape, radius, position and smoothness of the microfabricated hemispheres. These microlenses can readily be used for the fabrication of highly efficient light-emitting diodes.
Ridge waveguide, edge-emitting single quantum well GaAs lasers with an integrated gating electrode have been fabricated. These devices integrate a MESFET structure with the laser PN junction so that the SBD (Schottky barrier diode) depletion layer can be used for transverse current confinement in the laser. Device fabrication was very simple requiring only an anisotropic etch for waveguide definition followed by a single self-aligned contact deposition step. The Schottky barrier depletion layers on either side of the ridge waveguide act to confine free carriers. This structure allows for separation of the optical and electrical confinement in the transverse direction without requiring complex fabrication. The device demonstrated modulation of the pulsed lasing threshold with gate control voltage on a 30 micron wide ridge. Above threshold, increasing power output with increasing gate voltage was demonstrated with negligible gate current. The multimode lasing spectrum showed that the increased power output occurred for all modes with no shift in the mode wavelengths to within the resolution of the measurement system.
Conference Committee Involvement (12)
Photonic and Phononic Properties of Engineered Nanostructures XI
6 March 2021 | Online Only, California, United States
Photonic and Phononic Properties of Engineered Nanostructures X
3 February 2020 | San Francisco, California, United States
Photonic and Phononic Properties of Engineered Nanostructures IX
4 February 2019 | San Francisco, California, United States
Photonic and Phononic Properties of Engineered Nanostructures VIII
29 January 2018 | San Francisco, California, United States
Photonic and Phononic Properties of Engineered Nanostructures VII
30 January 2017 | San Francisco, California, United States
Photonic and Phononic Properties of Engineered Nanostructures VI
15 February 2016 | San Francisco, California, United States
Photonic and Phononic Properties of Engineered Nanostructures V
9 February 2015 | San Francisco, California, United States
Photonic and Phononic Properties of Engineered Nanostructures IV
3 February 2014 | San Francisco, California, United States
Photonic Crystal Materials and Devices IV
23 January 2006 | San Jose, California, United States
Photonic Crystal Materials and Devices III
24 January 2005 | San Jose, California, United States