Microwave sources based on high quality factor resonators; modeling, optimization and metrology

La technologie photonique-RF offre une alternative intéressante à l'approche purement électronique dans différents systèmes micro-ondes pour des applications militaires, spatiales et civiles. Un composant original, l'oscillateur optoélectronique (OEO), permet la génération de signaux RF stables et à haute pureté spectrale. Il est basé sur une liaison photonique micro-onde utilisée comme boucle de rétroaction et comportant soit une fibre longue, soit un résonateur à fort coefficient de qualité. Différentes études ont été menées au cours de cette thèse afin d'optimiser et d'améliorer la performance en termes de stabilité et de bruit de phase pour le cas de l'OEO à résonateur. La caractérisation fine et la modélisation des résonateurs est une première étape de la conception globale du système. La métrologie du résonateur optique est réalisée par une technique originale, dite de spectroscopie RF. Les résultats expérimentaux ont révélé que cette technique permet d'une part d'identifier le régime de couplage du résonateur et d'autre part de déterminer avec une grande précision tous les paramètres d'un dispositif résonant, comme les facteurs de qualité interne et externe ou les facteurs de couplage. Une deuxième étude a été orientée vers l'implémentation d'un modèle non-linéaire fiable du dispositif. Dans un tel modèle, la photodiode rapide nécessitait une description plus précise, dans le but de contrôler la conversion du bruit d'amplitude optique en bruit de phase de l'OEO. Un nouveau modèle non-linéaire d'une photodiode hyperfréquence a été développé sous un logiciel commercial: Agilent ADS. Ce nouveau modèle rend effectivement compte de cette conversion de bruit. Une puissance optique optimale à l'entrée de la photodiode a été déterminée, pour laquelle la contribution de RIN du laser au bruit de phase RF pourrait être négligeable. La performance de l'OEO est affectée par diverses perturbations entrainant un décalage en fréquence entre la fréquence du laser et la fréquence de résonance du résonateur. Il est donc important d'utiliser un système de stabilisation pour contrôler cette différence de fréquence. Des séries d'expériences et de tests ont été menées pour étudier la possibilité, d'une part, de remplacer l'électronique commerciale utilisée auparavant pour le système de verrouillage en fréquence (boucle de Pound-Drever-Hall) par une électronique faible bruit et, d'autre part, d'utiliser un laser à semi-conducteur. Un bilan de ces approches est présenté.RF photonics technology offers an attractive alternative to classical electronic approaches in several microwave systems for military, space and civil applications. One specific original architecture dubbed as optoelectronic oscillator (OEO) allows the generation of spectrally pure microwave reference frequencies, when the microwave photonic link is used as a feedback loop. Various studies have been conducted during this thesis on the OEO, especially the one that is based on fiber ring resonators, in order to optimize and improve its phase noise performance and its long-term stability. Precise characterization and modeling of the optical resonator are the first step towards overall system design. The resonator metrology is performed using an original approach, known as RF spectral characterization. The experimental results have demonstrated that this technique is helpful for the identification of the resonator's coupling regime and the accurate determination of the main resonator parameters such as the intrinsic and extrinsic quality factors or the coupling coefficients. A second study was directed toward implementing a reliable nonlinear model of the system. In such a model, the fast photodiode require an accurate description, in order to reduce the conversion of the optical amplitude noise into RF noise. A new nonlinear equivalent circuit model of a fast photodiode has been implemented in a microwave circuit simulator: Agilent ADS. This new model is able to describe the conversion of the laser relative intensity noise (RIN) into microwave phase noise at the photodiode output. An optimal optical power at the photodiode's input has been identified, at which the contribution of the laser RIN in RF phase noise is negligible. When it comes to practical applications, the desired performance of an OEO is threatened by various disturbances that may result in a frequency shift of both the laser frequency and the transmission peak of the resonator, which causes a malfunction of the OEO. Therefore it is desirable to use a stabilization system to control the difference between the laser frequency and the resonator frequency. A series of tests and experiments have been carried out to investigate the possibility, on one hand, to replace the commercial servo controller that was used up until now in the Pound-Drever-Hall loop, with a low noise homemade one and, on the other hand, to use a semiconductor laser to reduce the system size. A detailed review of these approaches is presented

Optical Communication

Optical communication is very much useful in telecommunication systems, data processing and networking. It consists of a transmitter that encodes a message into an optical signal, a channel that carries the signal to its desired destination, and a receiver that reproduces the message from the received optical signal. It presents up to date results on communication systems, along with the explanations of their relevance, from leading researchers in this field. The chapters cover general concepts of optical communication, components, systems, networks, signal processing and MIMO systems. In recent years, optical components and other enhanced signal processing functions are also considered in depth for optical communications systems. The researcher has also concentrated on optical devices, networking, signal processing, and MIMO systems and other enhanced functions for optical communication. This book is targeted at research, development and design engineers from the teams in manufacturing industry, academia and telecommunication industries

Models for planning the evolution of local telecommunication networks

Includes bibliographical references.Research initiated through a grant from GTE Laboratories, Inc. Supported in part by an AT&T research award. Supported in part by the Systems Theory and Operations Research Program of the National Science Foundation. ECS-8316224 Supported in part by ONR. N0000-14-86-0689A. Balakrishnan ... [et al.]

Models for planning the evolution of local telecommunication networks

Includes bibliographical references.Research initiated through a grant from GTE Laboratories, Inc. Supported in part by an AT&T research award. Supported in part by the Systems Theory and Operations Research Program of the National Science Foundation. ECS-8316224 Supported in part by ONR. N0000-14-86-0689A. Balakrishnan ... [et al.]

NASA/ASEE Summer Faculty Fellowship Program: 1988 research reports

This contractor's report contains all sixteen final reports prepared by the participants in the 1988 Summer Faculty Fellowship Program. Reports describe research projects on a number of topics including controlled environments, robotics, cryogenic propellant storage, polymers, hydroponic culture, adaptive servocontrol, and computer aided desig

Analysis of terabit/second-class inter-chip parallel optoelectronic transceiver

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 89-92).Electrical copper-based interconnect has been suffering from fundamental physical loss mechanism and its current infrastructure will not be able to meet the increasing demand for data rates due to reaching the limit of the transmission bandwidth-distance product. Optical interconnect has been known as the candidate for taking over the obsolete electrical counterpart owing to the capability of transmitting data at high rates with low loss and the feasibility for parallel integration. Optoelectronic transceiver is one of the essential elements in optical interconnect system. This thesis scrutinizes a complete set of constituent technologies developed for a novel inter-chip parallel optoelectronic (OE) transceiver (known as Terabus transceiver) which is able to communicate data at the speed in the range of Terabit/second. A novel packaging hierarchy and a creative design for an optical coupling mechanism devised to bring high-level integration and high-speed performance to a final package have been analyzed: Two 4x12 arrays (each < 9 mm2) of CMOS transmitter and receiver ICs have been flip-chip bonded to a silicon carrier interposer of 1.2-cm2 size. Other two 4x12 arrays of OE devices (VCSELs and photodiodes) with comparable size are then flip-chip bonded to the corresponding CMOS arrays attached to the silicon carrier, forming the Optochip assembly. The Optochip is in interface with an Optocard by the flip-chip bonding process between the silicon carrier and an organic card patterned with 48 integrated waveguides at density of 16-channel/mm and total length of 30 cm. The 985-nm operating wavelength of the lasers allows a simple optical design with emission and illumination through arrays of relay lenses directly etched into the backside of the OE Ill-V substrate. A novel design of 45*-tilted and Au-coated mirrors fabricated in 125-ptmpitch acrylate waveguides is to perpendicularly couple the light in and out of the core of these Optocard waveguides. Per-channel performance of up to 20 Gb/s for transmitter and of up to 14 Gb/s for receiver have been realized. Lastly, the thesis has analyzed the market opportunity of the transceiver by reviewing the market situation, identifying contemporary competing technologies, assessing the market prospect and predicting the cost.by Nguyen Hoang Nguyen.M.Eng

The Telecommunications and Data Acquisition Report

This quarterly publication provides archival reports on developments in programs managed by JPL's Telecommunications and Mission Operations Directorate (TMOD), which now includes the former Telecommunications and Data Acquisition (TDA) Office. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC)

Ultralow-noise modelocked lasers

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 343-357).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.The measurement, design, and theory of ultralow-noise actively modelocked lasers are presented. We demonstrate quantum-limited noise performance of a hybridly modelocked semiconductor laser with an rms timing jitter of only 47 fs (10 Hz to 10 MHz) and 86 fs (10 Hz to 4.5 GHz). The daunting task of measuring ultralow-noise levels is solved by a combined use of microwave and optical measurement techniques that yield complete characterization of the laser noise from DC to half the laser repetition rate. Optical cross-correlation techniques are shown to be a useful tool for quantifying fast noise processes, isolating the timing jitter noise component, measuring timing jitter asymmetries, and measuring correlations of pulses in harmonically modelocked lasers. A noise model for harmonically modelocked lasers is presented that illustrates how to correctly interpret the amplitude noise and timing jitter from microwave measurements. Using information about the supermodes, the amplitude and timing noise can be quantified independently, thereby making it possible to measure the noise of harmonically modelocked lasers with multi-gigahertz repetition rates. Methods to further reduce the noise of a modelocked laser are explored. We demonstrate that photon seeding is effective at reducing the noise of a modelocked semiconductor laser without increasing the pulse width. Experimental demonstrations of a timing jitter eater, consisting of a phase modulator and dispersive fiber, show that.(cont.) An analytical theory for semiconductor lasers that includes carrier dynamics is presented. Ultralow noise performance is achieved by reducing the dispersion of the cavity, reducing the linear losses in the cavity, by operating at high optical powers, and with a tight optical filter. The gain dynamics of the semiconductor laser do not severely degrade the noise performance.by Leaf Alden Jiang.Ph.D

Silicon Photonics Integrated Circuits for Flexible Optical Systems

This dissertation deals with the design and the characterization of novel reconfigurable silicon-on-insulator (SOI) devices to filter and route optical signals on-chip. Design is carried out through circuit simulations based on basic circuit elements (Building Blocks, BBs) in order to prove the feasibility of an approach allowing to move the design of Photonic Integrated Circuits (PICs) toward the system level. CMOS compatibility and large integration scale make SOI one of the most promising material to realize PICs. The concepts of generic foundry and BB based circuit simulations for the design are emerging as a solution to reduce the costs and increase the circuit complexity. To validate the BB based approach, the development of some of the most important BBs is performed first. A novel tunable coupler is also presented and it is demonstrated to be a valuable alternative to the known solutions. Two novel multi-element PICs are then analysed: a narrow linewidth single mode resonator and a passband filter with widely tunable bandwidth. Extensive circuit simulations are carried out to determine their performance, taking into account fabrication tolerances. The first PIC is based on two Grating Assisted Couplers in a ring resonator (RR) configuration. It is shown that a trade-off between performance, resonance bandwidth and device footprint has to be performed. The device could be employed to realize reconfigurable add-drop de/multiplexers. Sensitivity with respect to fabrication tolerances and spurious effects is however observed. The second PIC is based on an unbalanced Mach-Zehnder interferometer loaded with two RRs. Overall good performance and robustness to fabrication tolerances and nonlinear effects have confirmed its applicability for the realization of flexible optical systems. Simulated and measured devices behaviour is shown to be in agreement thus demonstrating the viability of a BB based approach to the design of complex PICs