Otto Schwelb

Transmission, group delay, and dispersion in single-ring optical resonators and add/drop filters-a tutorial overview

This tutorial describes the transmission, group delay time and quadratic dispersion properties of the four basic building blocs of optical filters built using ring resonators. These building blocs are single-ring resonators in either two-port (all-pass) or four-port (add/drop filter) configuration. The effect of waveguide and coupler loss is included throughout. Explicit expressions to compute the complex amplitude of the circulating wave in the ring, the Q factor, the finesse and the insertion loss are also given. Attention is drawn to the similarities between the ring resonator the Fabry-Pe/spl acute/rot resonator and the Gires-Tournois interferometer. Material properties and fabrication technology are not reviewed.

Generalized analysis for a class of linear interferometric networks. I. Analysis

A method is introduced to simplify the analysis and design of microwave and optoelectronic networks such as spectral filters, interferometric sensors, etc., comprised of 2/spl times/2 couplers, waveguides, reflectors, and mismatched interfaces. The key element which makes it possible to reduce topological complexity and rearrange a network into a chain of cascaded four-ports, is a generalized, single-mode lumped-element 2/spl times/2 coupler with arbitrary coupling paths. As a result, one can now enumerate and evaluate all possible feedback-assisted and resonant configurations. The emphasis is on providing a computationally efficient method of analysis applicable to a wide variety of networks, rather than on obtaining the simplest and most transparent analytical expressions for a particular configuration.

Photonic microresonator research and applications

Fundamental Principles of Operation and Notes on Fabrication of Photonic Microresonators.- Circular Integrated Optical Microresonators: Analytical Methods and Computational Aspects.- Polarization Rotation in Ring Resonators.- Series-Coupled and Parallel-Coupled Add/Drop Filters and FSR Extension.- Advanced Microring Photonic Filter Design.- Band-Limited Microresonator Reflectors and Mirror Structures.- Slow and Stopped Light in Coupled Resonator Systems.- Processing Light in Reconfigurable Directly Coupled Ring Resonators.- Microresonators with Active Tuning.- Performance of Single and Coupled Microresonators in Photonic Switching Schemes.- Single Molecule Detection Using Optical Microcavities.- Microfiber and Microcoil Resonators and Resonant Sensors.- Photonic Crystal Ring Resonators and Ring Resonator Circuits.- High-Q Photonic Crystal Microcavities.- Radial Bragg Resonators.- Photonic Molecules and Spectral Engineering.- Fundamentals and Applications of Microsphere Resonator Circuits.- MEMS-Tuned Microresonators.- Microresonators for Communication and Signal Processing Applications.

All-optical tunable filters built with discontinuity-assisted ring resonators

Numerically simulated performance is presented in a new type of bandstop and bandpass filters, built with discontinuity-assisted ring resonator (DARR)-loaded couplers. The operating characteristic of the bandpass filter is similar to that of a long grating with a centered cavity or a photonic crystal with a defect. The filters are tuned by varying the refractive index or the length of the waveguide forming the ring or the cavity. Selectivity and tuning range are controlled by the coupling coefficient of the couplers, by the order of resonance in the rings, and by the reflection coefficient of the discontinuities. A design procedure and the effect of loss are also presented.

Band-limited optical mirrors based on ring resonators: analysis and design

Ring-resonator-based optical mirrors are analyzed and their characteristics numerically evaluated. The mirrors are optimized to provide high reflection in a relatively narrow band. A design procedure that relates the required coupling to the bandwidth (BW) and reflection coefficient is presented. The effect of waveguide loss on the transmission and reflection performance is computed. Group delay and dispersion under the influence of loss and circuit-parameter variations are also treated.

Stratified lossy anisotropic media: general characteristics

Lossy gyroelectromagnetic layers in polar and longitudinal orientation are analyzed using the 4 × 4 matrix approach. Expressions are given for the coupling and transfer matrices, for the wave impedance, for the Poynting vector, and for the transmission and reflection coefficient characterizing an interface. The TE–TM coupling characteristics of an anisotropic layer are discussed.

Microring Resonator Based Photonic Circuits: Analysis and Design

Microring and microdisk resonators are used in photonic circuits to perform filter functions, serve as band- limited mirrors in lasers, compensate for dispersion and group delay distortion, are used in multiplexers in telecommunication systems, and a number of other applications such as medical instrumentation, biosensing, interferometry, to name a few. This paper outlines some challenges and solutions in this relatively new and prolific discipline.

Soliton propagation of microwave modulated signal through single-mode optical fiber

Sinusoidally modulated optical signal transmission is experimentally investigated over a 30 km standard single-mode fiber using a range of optical input powers. Experiments and computer simulations showed that fiber-induced self-phase modulation generates a chirp on the signal with an effect opposite to that induced by chromatic dispersion. Calculations were performed to investigate the distortions caused by simultaneous dispersion and non-linearity using a range of fiber parameters. Soliton propagation of the microwave/millimeter wave modulated signal is reported at elevated intensities in lossless and loss compensated cases.

Generalized analysis for a class of linear interferometric networks. Part II: Simulations

For pt.I see ibid., vol.46, no.10, pp.1399-408 (1998). In Part I of this paper, the author presented a method to simplify the analysis and design of interferometric microwave and optoelectronic networks such as filters, sensors, ring resonators, etc., comprised of 2/spl times/2 couplers, waveguides, reflectors, and mismatched interfaces. The simplification was achieved by introducing a generalized single-mode lumped-element 2/spl times/2 coupler with arbitrary coupling paths. In Part II, the author numerically examines a number of interferometric devices utilizing the analysis described in Part I. These devices include feedback-assisted couplers, multiple-ring resonators, unit transmittance circuits, add/drop filters, grating-assisted Mach-Zehnder (M-Z) interferometers, etc. Results are presented on the characteristics of the output and circulating wave in the resonant rings as a function of frequency, coupling coefficient, loss, and other component parameters. Results on group-delay characteristics are also given.

Characteristics of lattice networks and spectral filters built with 2/spl times/2 couplers

Results of numerical experiments on several interferometric networks built with 2/spl times/2 couplers are presented. The networks investigated include resonant and nonresonant lattices, generalized Mach-Zehnder (MZ) configurations and transversally coupled spectral filters. Several novel interferometric configurations and novel properties of known configurations are discussed. The numerical method is based on the concept of a universal coupler and on the generalized analysis of interferometric networks. It has been found that relatively simple configurations can provide the very high spectral selectivity needed in some communication applications and the flexibility desired in various sensor applications. Group delay and loss characteristics are also given.