Photonic crystal fibers (PCF) and conventional highly nonlinear fibers (HNLF) represent a new class of optical waveguide with novel dispersion and nonlinearity characteristics. In particular, these fibers allow us to strongly increase nonlinear effects while at the same time having control over multiple dispersion parameters. Many recent works have already exploited these properties for the generation of broadband spectra by means of supercontinuum generation. In order to study such spectral broadening, we need of course precise modeling of pulse propagation. Consequently, the extension of the existing models based on the nonlinear Schrödinger equation has been carried out to include effects such as the frequency response of the effective mode area and third harmonic generation. The consequences of such effects and new prospects for supercontinuum generation are described. Another attractive aspect of these novel optical fibers, in particular with HNLF, is their use in the important current development of femtosecond fiber sources, near the telecommunications wavelength at 1550 nm. Within this framework, two experimental systems were set up, respectively allowing us to obtain sub-30 fs pulses by nonlinear compression and to passively generate parabolic pulses. These devices are based on the use and management of very short lengths of commercial HNLF, leading to the implementation of ultracompact devices.
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