Transformation Of Femtosecond Pulses Research Articles

Spectral transformation of infrared ultrashort pulses in laser crystals

The impact of peculiarities of transparent media on the self transformation of femtosecond pulses is considered. Spectral width and intensity distribution of anti-Stokes part of supercontinuum generated by infrared femtosecond pulses in selected single crystals were determined for different pulse energy density as a function of incident pulse wavelength changed in the 800–1600nm region. Effect of material bandgap on the supercontinuum generation was examined based on experimental data for single crystals of gadolinium orthosilicate, gallium gadolinium garnet, lithium tantalate and lutetium vanadate. It was found that the anti-Stokes part of supercontinuum generated in Gd2SiO5 and Gd3Ga5O12 crystals has a quite large spectral width with a short wavelength cut-off around 450nm and contains a broad plateau.

Frequency conversion of subnanojoule femtosecond pulses in microstructure fibers

We experimentally demonstrate highly efficient multiplex frequency conversion of unamplified subnanojoule femtosecond pulses of Ti:sapphire laser radiation in fused silica microstructure fibers. Nonlinear optical spectral transformation of femtosecond pulses in an array of fused silica threadlike channels in these microstructure fibers results in the generation of isolated anti-Stokes spectral components within the wavelength range of 400–500 nm. An efficiency of frequency conversion of about 20% is achieved for 800-nm pump pulses with an energy of 0.7 nJ and a pulse duration of 70 fs.