the concept of shooting and bouncing rays. Taking into account that, in order to reach optical confinement into the cell, the mirror surfaces are concave shaped, the algorithm of shooting and bouncing attains a better behavior when compared with the optimization of the distance function, because the latter results in difficulties during the convergence process. The technique has been successfully validated using reported results. Very good agreement has been found between both the obtained and the reported reflection patterns. Due to the flexibility of the surface representation, works are in progress in order to evaluate the sensitivity to manufacturing tolerances and alignment processes. Finally, because NURBS surfaces are widely used in the field of solid modeling, the manufacturing process will easily integrate and put into practice the final designed cell. ACKNOWLEDGEMENTSThis work is co-funded by the Spanish Ministry of Science and Technology through the SuGAROS (TIC'2001-0877-C02-01) and EOAMOP (TIC'2002-01259 INTRODUCTIONSupercontinuum (SC), produced by various nonlinear effects in optical fibers such as self-phase modulation (SPM), four-wave mixing (FWM), and cross-phase modulation (XPM), is an attractive technology for providing an economical method to generate ultrashort pulses over a wide spectral range [1]. Recently, SC has been successfully applied in high-speed wavelength-division multiplexing (WDM) and wavelength-division multiplexing over optical-time-division multiplexing (WDM/OTDM) experimental systems [2,3]. When SC is followed by filters or array waveguide gratings (AWG), ultra-short optical pulses can be obtained. However, due to the complex SC generation mechanism [4], the SC spectrum and output pulses' profiles are intricate, as are the optical pulses' characteristics extracted from SC by filters. In order to fulfill the requirement of transmission systems, an in-depth study of these characters, which can guide the selection of different filters in different conditions, is crucial.In this paper, a 10-GHz active mode-locked Er 3ϩ -doped fiberring laser (AML-EDFL) is used as the optical pulse source. The pulses are compressed, amplified, and injected into SC fiber. We successfully extract optical pulses by filters, analyze the phenomena by experimental and numerical simulations, and draw some valuable conclusions. EXPERIMENT SETUPThe experimental setup is shown in Figure 1. The AML-EDFL was driven at 10 GHz and generated 10-ps chirp-free Gaussian pulses at 1552.7 nm. The pulse train was then amplified to an average optical power of 50 mW before being launched into the comb-like dispersion profiled fiber (CDPF) for pulse compression [5]. Then the compressed 2.1-ps pedestal-free pulse train was amplified to an average optical power of 20 dBm by EDFA2 before being injected into a 2-km dispersion-shifted fiber (DSF), which has a zerodispersion wavelength of 1550.87 nm and a 3 rd -order dispersion of 0.07 ps/nm 2 /km. The pulse trains, extracted by a tunable filter, were then measured by an opti...

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Based on three formulations of the Huygen's principle, explicit expressions is given for the far field contribution from a small ray tube. This expression is useful in shooting and bouncing rays for solving complex scattering problems.