Narrow Results

Effects of geometrical confinement and magnetic field strength on the binding energies of trions (positive trion and negative trion) in a CdTe/ZnTe parabolic dot are investigated. Coulomb interaction energy is obtained by employing Hartree potential and the results are found numerically. The modified Chandrasekhar wavefunctions are employed to obtain the respective energies. The confined energies and the respective binding energies of charged trions are investigated by the self-consistent method. The Poisson equation is used to find the electron and hole potentials. The dielectric mismatch is included throughout the calculations. Magneto-optical transition energies for charged trions in the presence of magnetic field are observed. The effective Landé factor is brought out. Raman shift and the Raman intensity of positive and negative trions for various magnetic field strengths in the CdTe/ZnTe nanostructures are investigated. The dependence of Raman resonance on the magnetic field and the geometrical confinement effect is brought out.

Raman scattering in air-covered and SiO₂-covered Silicon-on-insulator waveguides of 1.25 cm length, 220 nm height and two widths of 2 μm or 0.45 μm was investigated. A continuous wave (CW) Raman fiber laser at 1454.8 nm with linewidth of <0.1 nm was used as a pump source. The coupling efficiency was estimated to be around 10% for one end facet. Spontaneous Raman shift of 521 cm^-1 (1574.2 THz) scattering was observed at 1573.8 nm for SOI waveguides in air and 1574.2 nm for waveguides covered with SiO₂ at pump power of <1.5 mW inside both waveguides of 2 and 0.45 μm. Anti-Stokes scattering was observed at 1352.8 nm with pump power of 16 mW. The stimulated Raman gain was calculated from spontaneous Raman efficiency. Total Raman on-off gain was determined to be 0.6 dB for waveguide with width of 2 μm and 1 dB for waveguide with width of 0.45 μm.

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.

An improved model is proposed to approximate the actual Raman gain profile of silica, which in turn is used to calculate the power depletion of the shortest-wavelength channel due to all other channels in the system. In this improved model, the stimulated Raman scattering (SRS) effects from channels at the tail of Raman gain profile are taken into account. A statistical analysis is done for the SRS crosstalk in a wavelength division multiplexed system including modulation statistics. The bit error rate and power penalty are estimated, where the improved model for the Raman gain spectrum is used.