1,721,056 research outputs found
Improved optical transmitters for pulsed phase and intensity modulation
No full textTwo optical transmitters are described, generating new modulation formats based on the simultaneous modulation of the amplitude and the phase of an optical signal. The proposed formats are compared to the traditional Non-Return-to-Zero (NRZ), showing improved tolerances to chromatic dispersion (CD), differential group delay (DGD) and to wavelength division multiplexing (WDM) channel spacing, and requiring electronics with halved bandwidth. © 2005 Optical Society of America
A New Thermodynamic Approach to Multimode Fiber Self-cleaning and Soliton Condensation
Full text linkA new thermodynamic theory for optical multimode systems is proposed. Theory is based on a weighted Bose-Einstein law, and includes the state equation, the fundamental equation for the entropy and a metric to measure the accuracy of the thermodynamic approach. The theory is used to compare the experimental results of two propagation regimes in multimode fibers, specifically the self-cleaning in the normal chromatic dispersion region and the soliton condensation in the anomalous dispersion region. Surprising similarities are found in terms of thermodynamic parameters, suggesting a common basis for the thermalization processes observed in the two propagation regimes
Optical phase and intensity modulation using dark pulses
No full textA new optical modulation format is described, based on the simultaneous modulation of the amplitude and the phase of an optical signal. The proposed modulation format offers significant advantages in wavelength-division-multiplexing transmission, offering high spectral efficiency values, high extinction ratio, and requiring electronics with reduced bandwidth. © 2004 IEEE
Nonimaging optical concentrators using graded-index dielectric
No full textA new generation of inhomogeneous nonimaging optical concentrators is proposed, able to achieve simultaneously high optical efficiency and acceptance solid angle at a given geometrical concentration factor. General design methods are given, and concentrators are numerically investigated and optimized
An all optical NOR gate based on the interaction between cosine-shaped input beams of orthogonal polarization
No full textThe design of an all-optical NOR gate is presented. The logic operation is performed by the nonlinear Kerr interaction between beams that enter with cosine field shapes in a planar waveguide, as could be obtained, for example, by input channel guides. The beams have orthogonal polarizations. The gate is not phase dependent, grants a fan-out of two, and might also work in the presence of moderate nonlinear absorption
Single-channel transmission in dispersion management links in conditions of very strong pulse broadening: Application to 40 Gb/s signals on step-index fibers
No full textThe dynamic behavior of single-channel transmission on standard fibers with strong dispersion management has been theoretically and numerically analyzed. A single pulse and a pseudorandom pulse sequence have been compared in order to highlight the relevant role played by pulse interaction. A semi-analytical theory of the bandwidth evolution demonstrates that the introduction of prechirp is very important for controlling the single pulse propagation and numerical results show that such a chirp also permits to limit the nonlinear pulse interaction when other pulses are present. Simulations of a 40 Gb/s return-to-zero (RZ) system operating in links encompassing step-index fibers, by adopting a periodical compensation of the chromatic dispersion have been performed and results show that a record distance of 1300 km can be achieved with an amplifier spacing of 100 km. A compensation of the fiber third order dispersion would extend the transmission to 1800 km, which corresponds to the limits imposed by the amplified spontaneous emission (ASE) noise of the optical amplifiers
On the design of multipass dye laser amplifiers
No full textWe describe a universal method for designing multipass dye laser amplifiers typically pumped longitudinally by Q-switching high-energy pulses. The method is based on a set of normalized curves for the gain and on the experimental measurement of the amplifier noise. In this way, the method tries to maximize the gain and to reduce or control the losses in terms of amplified spontaneous emission and reabsorption of the signal by the uninverted amplifying material. It has been tested to design and optimize a high-gain multipass amplifier for picosecond pulses. The realized system has a compact geometry and offers a gain of over 36 dB, with output pulse energy of 14 mu J and few megawatts of peak power
Single-channel transmission in dispersion managed links in conditions of very strong pulse broadening: application to 40 Gbit/s signals on step-index fibers
No full textSummary form only given. Dispersion management (DM) techniques to periodically compensate for fiber chromatic dispersion, /spl beta//sub 2/, has been shown to be a useful strategy for increasing the capacity of optical communication systems. We show that optimal propagation conditions can be obtained by simultaneously minimizing nonlinear distortion on single pulses and nonlinear interactions among the pulses. As a result, a 40 Gbit/s soliton signal can be transmitted over a record distance of 1300 km in a link encompassing step-index fibers, with 100 km amplifier spacing and GVD compensation by gratings. Theoretically, minimization of nonlinear distortion can be obtained by analyzing the pulse bandwidth variation along the link
40-Gbit/s transmission in dispersion-management links with step-index fiber and linear compensation
No full textOptimal single-channel transmission can be obtained by simultaneously minimizing the nonlinear distortion of a single pulse and the nonlinear interaction among several pulses. This is demonstrated by numerical simulations based on a simple analytical theory of the chirp induced by the nonlinearity. The resulting fiber nonlinearity can be properly used to manage the pulse bandwidth evolution, allowing periodic behavior. As such, a 40 Gbit/s soliton signal can be transmitted over a record distance of 1800 km in a link that encompasses step-index fibers, with 100-km amplifier spacing and group-velocity-dispersion compensation by gratings
Four-wave-mixing reduction in fiber links with zero chromatic dispersion by limiting pulse overlapping
No full textThe four-wave mixing (FWM) process is examined by considering pulsed signals. It is shown that improvements to the performance of this process can be achieved by compensating the TOCD at the amplifier output and by using unequal delays among the channels
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