1,644 research outputs found
Photonic microwave harmonic generator driven by an optoelectronic ring oscillator
We describe a new architecture to generate microwave signals by optical means. Our system combines the advantages of two techniques: frequency multipliers and loop
oscillators. A frequency multiplier allows to obtain high
frequencies using frequency harmonic generation,
nevertheless, a very good quality reference signal is necessary to drive the system. In our setup, this reference signal is obtained using a loop oscillator. Optoelectronic loop oscillators generate signals with good performance in terms of phase noise and linewidth. We present the theory related to those techniques and the experimental data obtained
Complex Dynamics and Synchronization of Delayed-Feedback Nonlinear Oscillators
We describe a flexible and modular delayed-feedback nonlinear oscillator that
is capable of generating a wide range of dynamical behaviours, from periodic
oscillations to high-dimensional chaos. The oscillator uses electrooptic
modulation and fibre-optic transmission, with feedback and filtering
implemented through real-time digital-signal processing. We consider two such
oscillators that are coupled to one another, and we identify the conditions
under which they will synchronize. By examining the rates of divergence or
convergence between two coupled oscillators, we quantify the maximum Lyapunov
exponents or transverse Lyapunov exponents of the system, and we present an
experimental method to determine these rates that does not require a
mathematical model of the system. Finally, we demonstrate a new adaptive
control method that keeps two oscillators synchronized even when the coupling
between them is changing unpredictably.Comment: 24 pages, 13 figures. To appear in Phil. Trans. R. Soc. A (special
theme issue to accompany 2009 International Workshop on Delayed Complex
Systems
Merging of optoelectronic techniques for microwave signal generation
This paper describes some recent evolutions about optical generation of microwave signals. Among these, multiloop ring oscillator and harmonic generation allow both rise in frequency and wide tunability. Besides, using microresonators and optical sources like VCSEL (Vertical Cavity Surface Emitting Laser) induces better integration and lower power consumption. Taking advantage of these attractive features, a new architecture of photonic microwave source is proposed
Ultra-low phase noise all-optical microwave generation setup based on commercial devices
In this paper, we present a very simple design based on commercial devices
for the all-optical generation of ultra-low phase noise microwave signals. A
commercial, fibered femtosecond laser is locked to a laser that is stabilized
to a commercial ULE Fabry-Perot cavity. The 10 GHz microwave signal extracted
from the femtosecond laser output exhibits a single sideband phase noise
at 1 Hz Fourier frequency, at
the level of the best value obtained with such "microwave photonics" laboratory
experiments \cite{Fortier2011}. Close-to-the-carrier ultra-low phase noise
microwave signals will now be available in laboratories outside the frequency
metrology field, opening up new possibilities in various domains.Comment: 8 pages, 3 figures. To be published in Applied Optics, early posting
version available at
http://www.opticsinfobase.org/ao/upcoming_pdf.cfm?id=23114
Optoelectronic oscillators for communication systems
We introduce and report recent developments on a novel five port optoelectronic voltage controlled oscillator consisting of a resonant tunneling diode (RTD) optical-waveguide integrated with a laser diode. The RTD-based optoelectronic oscillator (OEO) has both optical and electrical input and output ports, with the fifth port allowing voltage control. The RTD-OEO locks to reference radio-frequency (RF) sources by either optical or electrical injection
locking techniques allowing remote synchronization, eliminating the need of
impedance matching between traditional RF oscillators. RTD-OEO functions include generation, amplification and distribution of RF carriers, clock recovery, carrier recovery, modulation and demodulation and frequency synthesis. Self-injection locking operation modes, where small portions of the output electrical/ optical signals are fed back into the electrical/optical input ports, are also proposed. The self-phase locked loop configuration can give rise to low-noise high-stable oscillations, not limited by the RF source performance and with no need of external optoelectronic conversion
Optoelectronic Oscillators
Patrice Salzenstein (2011). Optoelectronic Oscillators, Optoelectronic Devices and Properties, Oleg Sergiyenko (Ed.), ISBN: 978-953-307-204-3, InTech, Available from: http://www.intechopen.com/articles/show/title/optoelectronic-oscillatorsOptoelectronic devices impact many areas of society, from simple household appliances and multimedia systems to communications, computing, spatial scanning, optical monitoring, 3D measurements and medical instruments. This is the most complete book about optoelectromechanic systems and semiconductor optoelectronic devices; it provides an accessible, well-organized overview of optoelectronic devices and properties that emphasizes basic principles
Resonant Tunnelling Optoelectronic Circuits
Nowadays, most communication networks such as local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs) have replaced or are about to replace coaxial cable or twisted copper wire with fiber optical cables. Light-wave communication systems comprise a transmitter based on a visible or near-infrared light source, whose carrier is modulated by the information signal to be transmitted, a transmission media such as an optical fiber, eventually utilizing in-line optical amplification, and a receiver based on a photo-detector that recovers the information signal (Liu, 1996)(Einarsson, 1996). The transmitter consists of a driver circuit along a semiconductor laser or a light emitting diode (LED). The receiver is a signal processing circuit coupled to a photo-detector such as a photodiode, an avalanche photodiode (APD), a phototransistor or a high speed photoconductor that processes the photo-detected signal and recovers the primitive information signa
High spectral purity microwave sources based on optical resonators
L'optique constitue aujourd'hui une solution performante pour la rĂ©alisation de sources trĂšs pures en hyperfrĂ©quences, en particulier grĂące Ă l'approche de l'oscillateur Ă©lectro-optique (OEO). La puretĂ© spectrale de ces sources est essentielle pour les applications spatiales, militaires et pour la mĂ©trologie du temps et des frĂ©quences. Durant cette thĂšse, nous avons rĂ©alisĂ© et Ă©tudiĂ© diffĂ©rents types d'OEO Ă rĂ©sonateur optique en vue d'optimiser le bruit de phase de ce systĂšme. Nous avons en particulier orientĂ© nos travaux vers une approche originale utilisant un anneau rĂ©sonant fibrĂ© (ARF) passif. Ce type de rĂ©sonateur prĂ©sente en effet des coefficients de qualitĂ© optiques supĂ©rieurs Ă 109 pour des longueurs de fibre restant relativement faibles (L ~ 10 m) et facilement intĂ©grables dans un support planaire. En parallĂšle, nous avons menĂ© un travail important sur les oscillateurs Ă base de rĂ©sonateurs optiques 3D. Concernant l'OEO Ă ARF, des progrĂšs spectaculaires ont pu ĂȘtre obtenus grĂące Ă une meilleure comprĂ©hension des phĂ©nomĂšnes de bruit intrinsĂšques Ă ce systĂšme. Les deux types de bruit prĂ©pondĂ©rants Ă©taient la conversion du bruit du laser (FM et AM) en bruit de phase RF par diffĂ©rentes non-linĂ©aritĂ©s (dont la photodiode) et le dĂ©clenchement d'effets non-linĂ©aires optiques Ă l'intĂ©rieur du rĂ©sonateur. Le contrĂŽle de ces effets a permis en particulier d'Ă©liminer des remontĂ©es importantes de bruit sur le spectre de l'oscillateur, et d'atteindre un niveau de bruit de phase de -128 dBc/Hz Ă 10 kHz de la porteuse Ă 10.2 GHz en utilisant un OEO Ă base d'un ARF passif de 100 mĂštres de longueur, optimisĂ© et immunisĂ© contre les effets non-linĂ©aires optiques.Optics represents an elegant and reliable solution to generate high spectral purity microwave signals, especially the approach using the optoelectronic oscillator (OEO). The spectral purity of these sources is very important for space and military applications and also for time and frequency domain metrology. During this thesis, we have fabricated and studied many types of resonator based OEO in order to optimize the system phase noise. We have especially investigated an original approach using a passive fiber ring resonator (FRR). This resonator type can feature optical quality factors higher than 109 when only few meters of optical fibers are used (L ~ 10 m) and it can be easily integrated in a planar setup. Moreover, we have performed an important work on 3D WGM resonators based oscillators. In the FRR based OEO, spectacular progresses have been achieved thanks to a good understanding of the system intrinsic noise phenomena. Actually, we have found that the most important noise parameters were the laser FM and AM noise conversion into RF phase noise by means of different nonlinearities in the system (like the photodiode nonlinearity), but also by the generation of nonlinear optical effects inside the resonator. By controlling these effects, we have been able to reduce the OEO phase noise level and to reach a -128 dBc/Hz noise level at 10 kHz offset frequency from a 10.2 GHz carrier. This has been achieved using an OEO based on a 100m-long passive FRR, which has been optimized and immunized against different nonlinear optical effects
Photo-detectors integrated with resonant tunneling diodes
We report on photo-detectors consisting of an optical waveguide that incorporates
a resonant tunneling diode (RTD). Operating at wavelengths around 1.55 ÎŒm in the optical
communications C band we achieve maximum sensitivities of around 0.29 A/W which is
dependent on the bias voltage. This is due to the nature of RTD nonlinear current-voltage
characteristic that has a negative differential resistance (NDR) region. The resonant
tunneling diode photo-detector (RTD-PD) can be operated in either non-oscillating or
oscillating regimes depending on the bias voltage quiescent point. The oscillating regime is
apparent when the RTD-PD is biased in the NDR region giving rise to electrical gain and
microwave self-sustained oscillations Taking advantage of the RTDâs NDR distinctive
characteristics, we demonstrate efficient detection of gigahertz (GHz) modulated optical
carriers and optical control of a RTD GHz oscillator. RTD-PD based devices can have
applications in generation and optical control of GHz low-phase noise oscillators, clock
recovery systems, and fiber optic enabled radio frequency communication systems.info:eu-repo/semantics/publishedVersio
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