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Nonlinear optics at nanoscale is a recent fascinating research field. Among the numerous nonlinear optics phenomena, stimulated Raman scattering is one of the most interestingphenomena, due to its significant implications from both fundamental and applicative point of view. In this paper, the observations of stimulated Raman scattering, at the wavelengths of interest for telecommunications, in silicon nanocomposite and in amorphous silicon nanoparticles are reported. A significant Raman gain enhancement and a significant threshold power reduction with respect to silicon are demonstrated. Our findings indicate that nanostructured materials show great promise for Si-based Raman lasers. [ABSTRACT FROM AUTHOR]

The observation of stimulated Raman scattering in amorphous silicon nanoparticles embedded in Si-rich nitride/silicon superlattice structures (SRN/Si-SLs) is reported. Using a 1427 nm continuous-wavelength pump laser, an amplification of Stokes signal up to 0.9 dB/cm at 1540.6 nm and a significant reduction in threshold power of about 40% with respect to silicon are experimentally demonstrated. Our results indicate that amorphous silicon nanoparticles are a great promise for Si-based Raman lasers. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, silicon nanoparticles dispersed into a silica phase by sol–gel processing has been investigated by structural and nonlinear-optical characterization. The structural characterization has been performed by energy filtered and scanning transmission electron microscopy. A silicon nanoparticles mean radius of about 49nm and a nanoparticle density of about 1.62×108 dots/cm2 have been obtained. Regarding nonlinear optics characterization, the observation of stimulated Raman scattering and the realization of a Raman amplifier based on silicon nanocomposites are described. Using a 1427nm cw pump laser, amplification of Stokes signal, at 1542.2nm, up to 1.4dB/cm is demonstrated. A preliminary valuation of approximately a fivefold enhancement of the gain coefficient a significant reduction of threshold power are reported. Our findings have a potential interest for silicon-based Raman lasers. [Copyright &y& Elsevier]

Wetting phenomena in porous silicon layers are experimentally investigated by Raman scattering. The experimental results show a reversible blue-shift of Raman spectra of wetted porous silicon layers with respect to the unperturbed layers. We ascribe the shift to a compressive stress due to the increased lattice mismatch between the porous silicon layer and the bulk silicon substrate in wetting conditions. [ABSTRACT FROM AUTHOR]

In the last years, the possibility of light generation and/or amplification in silicon, based on Raman emission, has achieved great results. However, some significant limitations, inherent to the physics of silicon, have been pointed out, too. In order to overcome these limitations, a possible option is to consider low dimensional silicon. Along this line of argument, an approach based on Raman scattering in porous silicon is presented. We prove two significant advantages with respect to silicon: the broadening of spontaneous Raman emission and the tuning of the Stokes shift. Finally, we discuss the prospect of Raman amplifier in porous silicon. [ABSTRACT FROM AUTHOR]

In this paper, the optical dispersion properties and the Raman gain of sodium phosphate glasses containing niobium oxide at increasing concentrations have been systematically investigated, with the aim of establishing a potential enhancement of the Raman gain and its bandwidth with respect to silica. A broadening of the bandwidth and a higher peak Raman gain (approximately 17 times) than in silica glass have been observed at high niobium oxide molar content. Our findings point out that sodium-niobium-phosphate glasses could be utilized for the realization of Raman amplifiers. [ABSTRACT FROM AUTHOR]

In this paper, we report on the observation of stimulated Raman scattering in silicon nanocomposites, consisting of silicon nanoparticles dispersed in SiO2 matrix prepared by sol-gel method. Using a 1427 nm cw pump laser, amplification of Stokes signal, at 1542.2 nm, up to 1.4 dB/cm is demonstrated. A preliminary valuation of approximately a fivefold enhancement of the gain coefficient in Raman amplifier based on silicon nanocomposites with respect to silicon and a significant reduction of threshold power are also reported. These results have a potential interest for silicon-based Raman lasers. [ABSTRACT FROM AUTHOR]

In this paper, niobium-phosphate glasses doped with rare earths (Er and Sm) are investigated by Raman scattering. The goal of Raman characterization is twofold: (a) to perform a fine structural characterization of the synthesized glasses and (b) to measure the Raman gain coefficient of the samples and to compare it with fused silica. The results reveal the presence of NbO6 octahedra and Nb–O–P–Nb–O mixed chains. A broadening of bandwidth and a significant enhancement (∼24 times) in gain coefficient G with respect to conventional silica glasses are also demonstrated. [ABSTRACT FROM AUTHOR]

In this paper, we report on the observation of stimulated Raman scattering in amorphous silicon nanocrystals embedded in Si-rich nitride/silicon superlattice structures (SRN/Si-SLs). In particular, we have experimentally demonstrated amplification of Stokes signal up to 0.9 dB/cm at 1540.6 nm using a 1427 nm continuous-wavelength pump laser, consistent with a preliminary valuation of approximately a fourfold enhancement of the gain coefficient in Raman amplifier based on SRN/Si-SLs with respect to silicon. Finally, a significant reduction in threshold power of about 40% is also reported. Our findings indicate that silicon nanocrystals embedded in Si nitride-based superlattice structures show great promise for Si-based Raman lasers. [ABSTRACT FROM AUTHOR]

In the last three years, the possibility of light generation and/or amplification in silicon, based on Raman emission, has achieved significant results. However, limitations inherent to the physics of silicon have been pointed out, too. In this letter, an approach based on Raman scattering in porous silicon is investigated. Two significant advantages with respect to silicon are proved: the broadening of spontaneous Raman emission and the tuning of the Stokes shift. Finally, we discuss about the prospect of Raman amplifier in porous silicon. [ABSTRACT FROM AUTHOR]

There have been many reports regarding visible luminescence and light emission at 1.54 μm, at room temperature, from porous silicon and from Er-doped porous silicon, respectively. Described is a different approach, based on Raman scattering in porous silicon, to generate radiation at 1.54 μm. Preliminary experimental results regarding Raman emission in porous silicon samples at 1.54 μm are also reported. [ABSTRACT FROM AUTHOR]