Multiple passages of light through an absorption inhomogeneity of finite size deep within a turbid medium are analyzed for optical imaging by use of the self-energy diagram. The nonlinear correction becomes more important for an inhomogeneity of a larger size and with greater contrast in absorption with respect to the host background. The nonlinear correction factor agrees well with that from M...

We report our results on nonlinear optical properties of 2(3), 9(10), 16(17), 23(24) tetra tert-butyl phthalocyanine and 2(3), 9(10), 16(17), 23(24) tetra tert-butyl Zinc phthalocyanine studied using Z-scan technique with 800 nm femtosecond and 532 nm nanosecond pulses. Nonlinear absorption behavior in both femtosecond and nanosecond domains was studied in detail. We observed three-photon absor...

We investigate the linear and nonlinear optical responses of dilute anisotropic networks using the Green’s-function formalism (GFF)[Gu Y et al. 1999 Phys. Rev. B 59 12847]. For the different applied fields, numerical calculations indicate that a large third order nonlinear enhancement and a broad infrared absorption arise from the geometric anisotropy. It is also shown the overlap and separatio...

We study the instantaneous nonlinear index change in Al,,,Gac,sAs waveguides below the twophoton absorption edge and find Sphase shifts with 80 pJ, 0.4 ps pulses at wavelengths near 1.6 pm. These large phase shifts are obtained with less than 1 dB of loss from multiphoton absorption. Our results indicate that AlGaAs waveguides, which have a mature fabrication technology, can be used as compact ...

Single crystals of pure and Na doped L-arginine acetate (LAA) has been successfully grown from aqueous solution by slow evaporation technique. The crystalline qualities of the grown crystals were confirmed by powder X-ray diffraction studies. The nonlinear refractive index n2 and nonlinear susceptibility c(3) have been measured through the Z-scan technique. The results indicate that the compoun...

Parametric Raman nonlinearities in Silicon waveguides is used to demonstrate wavelength conversion from Stokes to anti-Stokes channels. The effects of two photon absorption and free carrier nonlinear losses on the conversion process have also been analyzed. We find that scaling down the waveguide dimensions to submicron sizes is advantageous in terms of increasing the Raman nonlinearities and r...

A new third order nonlinear optical single crystal of 2-phenylbenzimidazolium-ptoulenesulphonate (PBITS) was grown by the solvent evaporation technique using methanol as a solvent. The single crystal XRD analysis reveals that crystals belong to the triclinic system. An NMR and FTIR study confirms the formation and vibrational analysis present in the compound. UV-Vis absorption studies were also...

Nonlinear absorption has been detected and characterized by open aperture Z-scan in ionic liquids obtained by combination of 1-butyl-3-methyl-imidazolium cations with anions containing a transition metal (Zn) and thiocyanato groups. The laser source was a Ti:Sapphire oscillator (80-fs pulses, λ=810nm, repetition rate of 80.75MHz). This ionic liquid presents quite low heat capacity that favours ...

We present approximate analytical expressions describing nonlinear interaction of two optical waves copropagating inside a silicon waveguide in the presence of linear losses, stimulated Raman scattering, and free-carrier absorption. Our approach avoids the undepleted-pump approximation, which we show to be inadequate to describe accurately the Raman-gain process. Based on our calculations, we p...