Anti-Stokes Raman gain enabled by modulation instability in mid-IR waveguides

Abstract

The inclusion of self-steepening in the linear stability analysis of modulation instability (MI) leads to a power cutoff above which the MI gain vanishes. Under these conditions, MI in mid-IR waveguides is shown to give rise to the usual double-sideband spectrum, but with Raman-shaped sidelobes. This results from the energy transfer of a CW laser simultaneously to both Stokes and anti-Stokes bands in pseudo-parametric fashion. As such, the anti-Stokes gain matches completely the Stokes profile over the entire gain bandwidth. This remarkable behavior, not expected from an unexcited medium, is shown not to follow from a conventional four-wave mixing interaction between the pump and the Stokes band. We believe this observation to be of relevance in the area of Raman-based sensors which, in several instances, rely on monitoring small power variations of the anti-Stokes spectral component.

2–10 µm Mid‐Infrared Fiber‐Based Supercontinuum Laser Source: Experiment and Simulation

“…The strongest sidebands correspond to the MI‐enabled Stokes and anti‐Stokes Raman sidebands around 1.42 and 1.70 µm. [ 43 ] Around 1.51 and 1.59 µm are the residual MI sidebands from the silica fiber. Weak MI ZBLAN sidebands are visible around 1.39 and 1.755 µm.…”

Asymmetric modulation instability in nonlinear metamaterial waveguides

“…Experimental observations of the spontaneous modulation instability and the formation of rogue breathers as a result of coherent perturbation have been reported [15]. The characteristics of the Raman anti-Stokes band around the modulation instability power cutoff region have been investigated [16].…”

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

“…Coefficients β( ) and γ ( ) are the linear and nonlinear dispersion profiles, respectively, and it is customary to express these profiles as Taylor expansions. It is worth noting that although the NLSE has proved to be adequate to model pulse propagation in a wide variety of cases, it is well known that it does not necessarily conserve some basic physical quantities such as the number of photons and the energy [6,25,26]. In particular, the photon number is preserved only if τ sh = ω −1 0 , a fact often overlooked in the literature, which poses a severe limitation when applying the NLSE to arbitrary nonlinear profiles γ ( ).…”