Gabriele Manili

Ge-Doped Microstructured Multicore Fiber for Customizable Supercontinuum Generation

Supercontinuum generation in a multicore fiber in which several uncoupled cores were doped with dissimilar concentrations of germanium was studied experimentally. Germanium doping provided control over the separation between the zero-dispersion wavelength and the 1064-nm wavelength of a Q-switched Nd:YAG pump laser. Supercontinua generated independently in each core of the same piece of fiber displayed clear and repeatable differences due to the influence of germanium doping on refractive index and four-wave mixing. The spectral evolution of the subnanosecond pump pulses injected into the different cores was accurately reproduced by numerical simulations.

Four-Wave Mixing in Nonlinear Fiber With Two Intracavity Frequency-Shifted Laser Pumps

We experimentally study Bragg-type four-wave mixing frequency conversion in highly nonlinear fibers by using two independent frequency-shifted-feedback lasers. We obtain frequency conversion with partial coherent pumps when both lasers operate in the continuous-wave regime. Our experimental results compare well with numerical simulations, which take into account partial coherence of the two pumps.

Efficiency of dispersive wave generation in dual concentric core microstructured fiber

We describe the generation of powerful dispersive waves that are observed when pumping a dual concentric core microstructured fiber by means of a sub-nanosecond laser emitting at the wavelength of~1064 nm. The presence of three zeros in the dispersion curve, their spectral separation from the pump wavelength, and the complex dynamics of solitons originated by the pump pulse break-up, all contribute to boost the amplitude of the dispersive wave on the long-wavelength side of the pump. The measured conversion efficiency towards the dispersive wave at 1548 nm is as high as 50%. Our experimental analysis of the output spectra is completed by the acquisition of the time delays of the different spectral components. Numerical simulations and an analytical perturbative analysis identify the central wavelength of the red-shifted pump solitons and the dispersion profile of the fiber as the key parameters for determining the efficiency of the dispersive wave generation process.

Intra-cavity frequency shifted laser pumps for non-degenerate and partially coherent Bragg-Scattering FWM in nonlinear fiber

Nonlinear effects in fibers with partially coherent pumps have attracted a great interest in view of their potential for polarization insensitive wavelength conversion and the increased resilience to Stimulated Brillouin Scattering [1]. In this work we experimentally study the problem of non-degenerate four-wave-mixing (FWM) by using a pair of partially coherent pumps, and focus our attention on a specific type of FWM, which is generally called “Bragg-Scattering” (BS-FWM). This kind of FWM has attracted a renewed interest because of its intrinsically low-noise nature which makes it potentially applicable for light-by-light manipulation even for very faint signals such as quantum keys [2].

Soliton triads ensemble in frequency conversion: from inverse scattering theory to experimental observation

We consider the spectral theory of three-wave interactions to predict the initiation, formation and dynamics of an ensemble of bright-dark-bright soliton triads in frequency conversion processes. Spatial observation of non-interacting triads ensemble in a KTP crystal confirms theoretical prediction and numerical simulations.

Optical continuum generation seeded by stimulated Raman scattering

An optical continuum was generated in microstructured optical fibre using an incoherent pump generated by stimulated Raman scattering in a step index fibre with normal dispersion. Accelerated spectral broadening to longer wavelengths was observed.