Sub-10-fs deep-ultraviolet light source with stable power and spectrum

Femtosecond electronic relaxation and real-time vibrational dynamics in 2′-hydroxychalcone

Electronic relaxation, proton transfer and instantaneous vibrational frequency change after the impulsive excitation by a deep ultraviolet 9 fs pulse were studied.

Ultrafast waveform synthesis and characterization using coherent Raman sidebands in a reflection scheme

Coherent Raman sidebands have the potential to serve as a source of single cycle pulses. We generate these sidebands by crossing two-color femtosecond laser pulses in a Raman-active crystal. We design a reflection scheme using spherical mirrors to combine coherent Raman sidebands. The sidebands and the driving pulses are refocused back to the Raman crystal and the relative spectral phases are retrieved from an interferogram based on the nonlinear Raman interaction. Furthermore, using a deformable mirror to adjust the spectral phases, we demonstrate that our setup is capable of synthesizing ultrafast waveforms using coherent Raman sidebands.

Coherent broadband light generation with a double-path configuration

We generate broadband light by focusing two femtosecond pulses into a Raman-active crystal. By reflecting Raman sideband beams together with the two driving beams back to the same crystal (with a slight spatial offset), we generate sidebands covering a broader spectral range, compared to a single pass. In this novel double-path configuration, multiple Raman sideband beams interact with each other since the phase-matching condition is automatically fulfilled. This scheme enables an enhanced cascaded coherent anti-Stokes scattering process and also doubles the interaction length, thus it allows one to use relatively weak energy pump pulses and thereby avoid optical damage.