Nonlinear optical properties of semiconductor-doped sol-gel waveguides

Thin silica-titania films eloped with CdS and PbS nanocrystals have been pr epared by the sol-gel route. Their nonlinear properties have been studied u sing the techniques of degenerated four wave miring and m-lines with picose cond (ps) and nanosecond laser pulses. Depending on wavelength, doping leve l, and laser pulse duration, high negative nonlinearity was found for CdS-d oped (n(2) = -2 x 10(-8) cm(2) /kW) and PbS-doped films (-10(-10) to -2 x 1 0(-7) cm(2)/kW). The response time of the nonlinearity was below 35 ps. Sat uration of the nonlinearity was observed. Straight, monomode channel wavele nght have been, fabricated on these films. The influence of MIE-scattering due to the nanoparticles is investigated.