A method for fabrication of a new type of optical fiber with dispersion varying along the fiber length is described. The main optical parameters of a drawn fiber are theoretically studied and experimentally measured. These fibers are of great interest for nonlinear fiber optics. Such applications of the fibers, such as high-quality soliton pulse compression, soliton pulsewidth stabilization through compensation of losses, and generation of a high-repetition-rate train of practically uninteracting solitons, are considered.

We experimentally demonstrate the possibility to generate parabolic pulses via a single dispersion decreasing optical fiber with normal dispersion. We numerically and experimentally investigate the influence of the dispersion profile, and we show that a hybrid configuration combining dispersion decrease and gain has several benefits on the parabolic generated pulses.

We examine similarities and differences between high-power parabolic pulse generation in an active medium and in tapered fiber with decreasing normal dispersion. Using a realistic tapered fiber design, we demonstrate the possibility of parabolic pulse generation without an external pump and determine the limitations of this approach. © 2007 Optical Society of America OCIS codes: 060.2280, 060.4370, 060.5530, 320.5540. High-power pulse propagation in optical fiber is strongly affected by nonlinear phenomena. Mastering these nonlinear effects can result in the development of new attractive techniques for optical signal generation, processing, and manipulation. In the normal dispersion regime, nonlinear-dominated optical pulse broadening generally leads to wave breaking that manifests itself as waveform steepening with subsequent growing oscillations at the pulse tails. However, there is an interesting class of breakingfree pulses with a parabolic profile in the energycontaining core that can propagate in a stable selfsimilar manner, holding a certain relation (scaling) among changing pulse power, width, and chirp. 1 Such a parabolic pulse can be analytically described as an approximate solution of the nonlinear Schrödinger equation (NLSE) with normal dispersion and gain in the large-amplitude (or small-dispersion) limit. [1][2][3][4][5] Note that the self-similar parabolic approximation is applied only in the central part of the pulse. A more accurate mathematical description that matches the parabolic core with the pulse tails has been presented in Ref. 6. Parabolic pulses (PPs) have recently attracted a great deal of attention because of their potential importance for high-power femtosecond lasers, 7-9 applications in spectral broadening and supercontinuum generation, 10,11 and all-optical signal processing and regeneration. 12,13 Generation of PPs by using an optical fiber amplifying medium (e.g., Er-doped fiber amplifiers, Ybdoped fiber, or passive optical fibers with distributed Raman amplification) has been successfully demonstrated in a number of recent publications (see, e.g., Refs. 14 and 15 and references therein). Breakingfree optical pulse amplification is beneficial for highpower lasers and similar applications. However, there is a range of physical and technical problems (e.g., telecommunication signal processing) where high signal power is not required and the most valuable features are the specific parabolic pulse shape and chirp. An active medium, inevitably, introduces amplified spontaneous emission noise. Therefore, taking into account a variety of possible applications, it is of interest to examine other approaches to PP generation. A simple alternative method for generation of PPs in a passive device by means of a dispersion-decreasing fiber (DDF) was proposed in Ref. 16. The first experiments 17,18 confirmed the possibility of PP generation in DDF. It was pointed out in Ref. 16 that in a system described by the ideal lossless NLSE with dispersion decreasing as D͑z͒ = D͑0͒ / ͑1+⌫ 0 z͒ (hyp...

We experimentally study the dynamics of the generation of multiple sidebands by means of a quasi-phase-matched four-wave mixing (FWM) process occurring in a dispersion-oscillating, highly nonlinear optical fiber. The fiber under test is pumped by a ns microchip laser operating in the normal average group-velocity dispersion regime and in the telecom C band. We reveal that the growth of higher-order sidebands is strongly influenced by the competition with cascade FWM between the pump and the first-order quasi-phase matched sidebands. The properties of these competing FWM processes are substantially affected when a partially coherent pump source is used, leading to a drastic reduction of the average power needed for sideband generation.

We report direct generation of <500-fs pulses at a 1-GHz rate from a self-starting passively mode-locked fiber laser by regeneratively synchronizing the pulses with a phase modulator. The pulses are amplified and passed through a dispersion-decreasing fiber and a normal-dispersion supercontinuum fiber. The resulting continuum is wider than 350 nm.

The fibers with dispersion varying along length have important applications in optical signal processing such as high-quality optical pulse compression, stable continuum generation, nonlinear dynamic dispersion compensation and other applications. This paper describes the basic idea and experimental results.

We have proposed and tested a novel design of a short-length dispersion-managed hybrid highly nonlinear fiber (HNLF), which is intended for low-noise spectral supercontinuum generation with controlled intensity distribution over the range 1-2 µm. It is shown experimentally that such a HNLF facilitates development of a mobile femtosecond optical clockwork, which is based on a fiber-optic femtosecond laser system and an original fiber-coupled Nd : YAG/I 2 optical frequency standard with a long-term instability lowered to 3 × 10 -15 .

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