Supercontinuum generation from 2 to 20  μm in GaAs pumped by picosecond CO_2 laser pulses

Abstract

We report on the generation of supercontinuum radiation from 2 to 20 μm in a 67 mm long GaAs crystal pumped by a train of 3 ps CO2 laser pulses. Temporal measurements indicate that sub-picosecond pulse splitting is involved in the production of such wide-bandwidth radiation in GaAs. The results show that the observed spectral broadening is heavily influenced by four-wave mixing and stimulated Raman scattering.

Ultrafast supercontinuum generation in bulk condensed media

“…2-20 μm spanning picosecond SC in GaAs was reported using 2.5 ps, 9.3 μm pulses from a CO 2 laser [247]. In the femtosecond regime, output spectrum spanning wavelengths from 3.5 to 7 μm was generated in a 10-mm thick GaAs crystal when pumped by 100 fs pulses with a central wavelength of 5 μm, as obtained by the difference frequency generation between the signal and idler pulses of the Ti:sapphire laser-pumped near-infrared optical parametric amplifier [248].…”

Generation of high power, sub-picosecond, 10 µm pulses via self-phase modulation followed by compression

“…In our first experiment we have stretched the 2 GW CO 2 pulses to ~ 6 ps and propagated them through 21 mm of GaAs. It should be noted that, without stretching the pulses, we risk self-compression and eventual pulse break-up via modulational instability [13]. After the 21 mm of GaAs we observe an increase of the laser pulse's bandwidth from ~ 50 nm to 150 nm, FWHM.…”

“…2, the temporal structure consists of 3 ps pulses separated by 18.5 ps. While this system has been used for novel nonlinear optics experiments at 10 µm [13], the power of the system must be increased in order to reach the 0.1 -1 TW powers required to study advanced acceleration schemes at a high repetition rate.…”

Multiple-μJ mid-IR supercontinuum generation in quadratic nonlinear crystals

“…They rely mainly on self-phase modulation (SPM) spectral broadening in bulk glasses or crystals [1]- [3], eventually limited by the onset of multiple filamentation due to the self-focusing nature of the SPM effect, and thus to few-µJ energies [? ], [4]- [6].…”