Nonlinear Fiber Optics: Concepts, applications, and advanced topics

Teachers : Philippe Grelu / Guy Millot / John Dudley

Nonlinear fiber optics

This course introduces the fundamental physical effects and concepts that underlie the propagation of short and ultrashort optical pulses in dielectric waveguides. It elaborates on the major dispersive effects that generally dominate the first stages of propagation of short pulses within passive optical fibers: chromatic dispersion and Kerr nonlinearity. This allows to define several propagation regimes, with an emphasis on optical soliton propagation, along with a variety of fascinating nonlinear phenomena, such as self-phase modulation, four-wave mixing, modulation instability, optical rogue waves and supercontinuum generation. The contributions of Raman and Brillouin scattering in optical fibers are also discussed, and the notions of the course are illustrated in the context of optical communications.

Contents:

• Introduction: from nonlinear optics to nonlinear fiber optics.
• Dispersive effects on short pulses. Propagation equation for the pulse envelope.
• Dispersion-induced broadening of Gaussian pulses.
• Nonlinear optics in dielectric fibers. Third-order nonlinear effects.
• The nonlinear Schrödinger equation. Propagation regimes.
• The optical soliton. Bright solitons, high-order solitons, dark solitons.
• Modulation instability.
• Raman and Brillouin scattering in optical fibers.
• Implications for optical communications.
• Supercontinuum generation and optical rogue waves.

Nonlinear optical dynamics & fiber lasers

We consider in this course the fiber laser cavity as a complex system where pulse propagation is augmented with gain, loss, and a feedback loop effect from the laser cavity. This system allows us to illustrate a recent concept of soliton: the dissipative soliton, and to present the background of nonlinear dynamics, with the concepts of dynamical attractors and bifurcations. Dissipative solitons are localized formations of an electromagnetic field that are balanced through an energy exchange with the environment in presence of nonlinearity, dispersion and/or diffraction. The concept of a dissipative soliton provides an excellent framework for understanding complex pulse dynamics and stimulates innovative cavity designs. Reciprocally, the field of mode-locked fiber lasers serves as an ideal playground for testing the concept of dissipative solitons and revealing their unusual dynamics. This course highlights striking self-organized pulse patterns such as optical soliton molecules and explains the implications for the design of high-energy mode-locked fiber laser cavities.

Contents:

• Ultrafast fiber lasers and applications.
• From solitons to dissipative solitons.
• Mode-locked fiber laser technology.
• Complex ultrafast cavity dynamics.
• Advanced optical characterization (dispersive time-stretch method).
• High-energy fiber laser architectures.

Advanced topics in nonlinear and ultrafast fiber optics

We discuss advanced topics relevant to the physics and applications of nonlinear ultrafast optics. Subjects covered include: Ultrashort pulses – description and techniques for characterisation, particularly frequency resolved optical gating; fibre frequency conversion processes including supercontinuum generation and applications; nonlinear localisation effects and optical rogue waves; state-of-the-art topics from the current research literature are also discussed as part of this class.