Front-induced transitions

Abstract

Moving refractive index fronts in dispersive waveguides is a special type of spatio-temporal modulation. The interaction of light with such fronts can be described in terms of an indirect transition where the frequency and wavenumber of a guided mode both are changed. In recent years front induced transitions were used in dispersion engineered waveguides for frequency conversion, optical delays, and bandwidth and pulse duration manipulation. These concepts have originated from different research areas of photonics, such as nonlinear fiber optics, slow light waveguides, plasma physics, moving media and relativistic effects. Here, we would like to review these concepts, providing a unifying theoretical description and highlight the potential of this exciting research field for light manipulation in guided optics.

All-optical pulse-train generation and distributed sensing through the temporal analogue of a laser

“…Finally, in Section 5 we present our conclusions. The temporal analogy of reflection and refraction has already been demonstrated in media with a time-dependent refractive indices [15][16][17]34]. As it was mentioned in the previous section, this can be achieved by means of an intense (pump) pulse propagating in an optical fiber, where the change in the refraction index is a consequence of the optical Kerr effect.…”

“…In the past years, the temporal analogue of reflection and refraction laws has attracted the attention of the nonlinear optics community [15][16][17]. It relies on the Kerr effect induced by high-intensity pulses propagating in a nonlinear fiber that play the role of moving refractive-index boundaries [18,19].…”

“…[16], the frequency shift involved in the change of group velocities completes this analogy by acting as the incident and refracted angles in Snell's law. This scheme has been exploited to study different applications such as the splitting of pulses [20], wavelength conversion, optical delays, and pulse manipulation in the time and frequency domains [17], the study of plasmonic behavior [21], pulse interference [20], and many others [18,19,22,23].…”

Optical analogues of black-hole horizons

“…The horizon dynamics was also related to the formation of optical rogue waves and champion solitons [81–84], and the ability to form all-optical transistors [85]. Similar ‘front-induced transitions’ were studied in other areas of photonics [86], and the quest for measuring analogue Hawking radiation continued.…”

Measuring self-steepening with the photon-conserving nonlinear Schrödinger equation

“…Self-steepening (SS) is a nonlinear effect responsible for the optical shock of ultrashort pulses that acquires singular relevance when analyzing the dynamics of broadband spectra, such as in the case of supercontinuum generation [1,2], and with applications to optical front-induced transitions [3]. SS is customarily introduced in pulse propagation models through a first-order approximation of the frequency dependence of the medium nonlinear coefficient.…”