Fluorophosphate glasses doped with PbSe quantum dots and their nonlinear optical characteristics

A new fluorophosphate glass matrix containing PbSe quantum dots characterized by a narrow size distribution (Delta R/R similar to 5-7%, where R is the size of a quantum dot) is prepared under heat treatment. It is demonstrated that fluorophosphate glasses can be doped by introducing (ZnSe + PbO) or PbSe into the composition of the glass. The optical absorption spectra of the quantum dots corresponding to the strong quantum confinement regime are studied over a wide range of quantum-dot sizes (4-18 nm). The nonlinear optical absorption is investigated at a wavelength of 1.54 mu m. It is revealed that the introduction of (ZnSe + PbO) rather than of PbSe into the composition of the glass improves the bleaching contrast owing to a more uniform distribution of the quantum dots over the volume of the glass sample

Absorption saturation properties and laser Q-switch performance of Cr5+-doped YVO4 crystal

The ground-state and excited-state absorption cross sections of a Cr5+:YVO4 single crystal were determined by the intensity-dependant transmission measurements to be(2.0±0.4)×10-18 cm2 and less than 0.1×10-18 cm2 at 1.08 μm, respectively. The bleaching relaxation time of the Cr5+:YVO4 crystal was estimated to be 3.5±1.5 ns. Passive Q-switching of a diode-pumped Yb3+:YVO4 laser with the Cr5+:YVO4 saturable absorber was realized