Modelling of photonic components based on ÷(3)nonlinear photonic crystals

En esta tesis se llevó a cabo un estudio de diversas propiedades de los cristales fotónicos 1D y 2D no lineales de tercer orden y de cómo se pueden aplicar dichas propiedades al desarrollo de dispositivos totalmente ópticos (por ejemplo, limitadores y conmutadores, compuertas lógicas, transistores ópticos, etc.). Se propuso una aproximación numérica para calcular las características básicas de los cristales fotónicos no lineales como, por ejemplo, el diagrama de bandas o la transmisión. La aproximación numérica presentada en la tesis tiene ciertas ventajas útiles para cualquiera que diseñe dispositivos ópticos basados en cristales fotónicos no lineales. El sofware desarrollado a base de esta aproximación numérica ha permitido diseñar y simular numéricamente un conmutador totalmente óptico cuyas prestaciones son superiores a las de dispositivos optoelectrónicos convencionales.This dissertation represents a summary of a study of different properties of 1D and 2D third-order nonlinear photonic crystals. It is shown how these properties can be utilized to develop various all-optical devices (e.g. optical limiters and switches, logical gates, optical transistors, etc.) In the dissertation, a novel numerical approximation has been proposed for analyzing the basic characteristics of the nonlinear photonic crystals like dispersion characteristics or transmittance curves. This numerical approximation possesses some important advantages useful in designing all-optical devices based on nonlinear photonic crystals. The software based on its algorithm has allowed to design and simulate a high-production all-optical switching device

Modeling phonon-polariton generation and control in ferroelectric crystals

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 101-109).In this thesis, we present simulations, using Finite Element Method (FEM), of phonon-polariton generation and coherent control in ferroelectric crystals LiNbO₃ and LiTaO₃ through nonlinear electro-optic interactions with ultrashort laser pulses. This direct space-time monitoring platform is used to investigate the nature of the excitation mechanism, the science of propagation in patterned structure, and the waveform control via multi-dimensional pulse shaping. Compared with previous simulation methods, this platform demonstrates considerable improvement in complex domain by achieving varied accuracy over space based on the level of interest of the region, which may facilitate scientific exploration in high power terahertz generation and polaritonic signal processing.by Zhao Chen.S.M

Polaritonics : an intermediate regime between electronics and photonics

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Vita.Includes bibliographical references (p. 279-290).This thesis contains the foundational work behind the field of polaritonics. Corresponding to a frequency range from roughly 100 gigahertz up to 10 terahertz, polaritonics bridges the gap between electronics and photonics. In this regime, signals are carried by an admixture of electromagnetic and lattice vibrational waves known as phonon-polaritons, rather than currents or photons. Impulsive stimulated Raman scattering (ISRS) is employed for phonon-polariton generation, whereby lattice vibrations are driven by optical femtosecond laser pulses directed into ferroelectric LiNbO3 or LiTaO3. The vibrational amplitude is proportional to the intensity of the excitation pulses. Due to the high dielectric constants of these crystals, phonon-polaritons travel in a predominantly lateral direction away from the excitation region. Lateral propagation is further facilitated by employing crystals whose thickness is on the order of the phonon-polariton wavelength, such that propagation occurs within one or more of the slab waveguide modes of the crystal. Direct observation of phonon-polaritons is achieved using real-space imaging, which monitors and records the spatiotemporal evolution of phonon-polaritons within a ferroelectric crystal. The details of both broadband and narrowband phonon-polariton generation and propagation in bulk and thin film crystals are presented. Additionally, robust polaritonic waveform generation is illustrated that relies on temporal or spatial shaping of the optical excitation pulses. Guidance, control, and other types of signal processing are demonstrated by patterning of the host crystal using femtosecond laser micromachining.(cont.) Waveguides that direct propagation, resonators that confine polaritonic signals, reflectors that direct, shape, and focus polaritonic waveforms, and periodic photonic crystal structures that restrict phonon-polaritons to a narrow band of frequencies are fabricated and their functionality demonstrated. The details of the laser micromachining employed for fabrication of these structures in a variety of crystal thicknesses are also presented here. Experimental measurements are supported by a novel implementation of finite-difference- time-domain (FDTD) simulations that accurately model both phonon-polariton generation and propagation in bulk, thin film, and patterned crystals. Additionally, numerical experiments are performed to predict functionality that will enable advanced polaritonic bistable devices for use in digital polaritonics and negative refractive polaritonic materials for unique waveform generation, signal processing, and sub-diffraction terahertz imaging. Polaritonics offers lower signal-to-noise than photonics and higher bandwidth signals than electronics, with generation, propagation, guidance, and control integrated into a single all- optical platform. Direct visualization of signal propagation makes device design and testing substantially easier than in either electronics or photonics. With continued development, fabrication of polaritonic materials should prove less demanding than traditional photonic structures, as it requires feature sizes on the order of micrometers rather than nanometers. Due to the high terahertz electric field strengths associated with ISRS phonon-polariton generation and the robust signal processing tool chest presented here, polaritonics promises to be useful in various spectroscopic applications including, but not limited to, linear and nonlinear terahertz spectroscopy and terahertz near field microscopy.by David W. Ward.Ph.D

Direct experimental visualization of waves and band structure in 2D photonic crystal slabs

We demonstrate for the first time the ability to perform time resolved imaging of terahertz (THz) waves propagating within a photonic crystal (PhC) slab. For photonic lattices with different orientations and symmetries, we used the electro-optic effect to record the full spatiotemporal evolution of THz fields across a broad spectral range spanning the photonic band gap. In addition to revealing real-space behavior, the data let us directly map the band diagrams of the PhCs. The data, which are in good agreement with theoretical calculations, display a rich set of effects including photonic band gaps, eigenmodes and leaky modes.National Science Foundation (U.S.) (Grant no. 1128632)National Science Foundation (U.S.) (NSF GRFP Fellowship)Canadian Institutes of Health Research (Fellowship

Phonon polariton interaction with patterned materials

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.Vita.Includes bibliographical references (p. 139-144).The generation, propagation and detection of THz phonon polaritons are studied through both femtosecond pump-probe techniques, and Finite Difference Time Domain (FDTD) simulations in this thesis. The theory surrounding the driving, propagation and detection of these modes is treated in a consistent notational system for both analytical solutions and approximate simulated responses. FDTD simulations in one, two and three dimensions are designed to best mimic lab experimental parameters, with various approximations of both THz pumping and probing developed. Various improvements on the FDTD method with the goal of more rapid simulations and more accurately described simulations of lab experiments from generation to detection are considered and developed. Experiments on phonon-polaritons interacting with periodicity and confinement in one, two, and three dimensions are all considered, and methods of data processing developed. By comparing FDTD simulation results to experimental results, the full three dimensional fields within these crystals can be investigated, and in many cases fully defined. The methods demonstrated open up new possibilities for THz spectroscopy in waveguides, microfluidics, and related platforms that include THz generation, propagation, interaction with the sample material, and detection in a compact, integrated structure. The methods also enable the proper description of large-amplitude THz generation and applications in nonlinear THz spectroscopy. Finally, linear and nonlinear THz signal processing applications my exploit the experimental and modeling methods described in this thesis.by Eric R. Statz.Ph.D

Theory of optical rectification in a travelling wave structure

This thesis is concerned with the interaction of an optical wave with a microwave in a waveguiding structure coupled by a second order nonlinearity. Emphasis is laid upon the generation of ultrashort electrical transients via optical rectification (OR) as well as cascading effects due to the interplay of OR and the linear electro-optic effect. A simple transmission line model is introduced to explain qualitatively the basic physical mechanisms of an externally induced polarisation in a travelling wave structure. For a quantitative description, evolution equations for the overall interaction between the microwave and the optical wave based on a coupled mode formalism are developed. The basic properties of the structure under consideration are discussion and techniques for their evaluation are introduced. A set of corresponding parameters for typical structures is estimated and used for calculations throughout the thesis. The generation of electrical signals from optical waves via OR is discussed in detail for the cases of single and mixed polarization optical modes in the structure. The self phase modulation due to cascading of OR and the electro-optic effect is elucidated. It is shown that continuous wave solutions of the conservative system are modulationally unstable in a large range of relevant system parameters. The possibility of formation of solitary waves due to the mutual interaction of optical wave and microwave is considered in the context of long wave short wave interaction. Basic properties of bright stationary solutions and their excitation are discussed. The possibility of formation of solitons due to microwave self-interaction is illuminated. The linear stability of bright solitary waves is investigated. The observed oscillations and radiation of perturbed propagated bound states are explained by the existence of discrete, quasi-bond internal modes of the stationary solutions. Collision scenarios are addressed

Optics and Quantum Electronics

Contains table of contents for Section 3 and reports on twenty research projects.Charles S. Draper Laboratories Contract DL-H-467138Joint Services Electronics Program Contract DAAL03-92-C-0001Joint Services Electronics Program Grant DAAH04-95-1-0038U.S. Air Force - Office of Scientific Research Contract F49620-91-C-0091MIT Lincoln LaboratoryNational Science Foundation Grant ECS 90-12787Fujitsu LaboratoriesNational Center for Integrated PhotonicsHoneywell Technology CenterU.S. Navy - Office of Naval Research (MFEL) Contract N00014-94-1-0717U.S. Navy - Office of Naval Research (MFEL) Grant N00014-91-J-1956National Institutes of Health Grant NIH-5-R01-GM35459-09U.S. Air Force - Office of Scientific Research Grant F49620-93-1-0301MIT Lincoln Laboratory Contract BX-5098Electric Power Research Institute Contract RP3170-25ENEC