Sub-1.5-cycle pulses from a single filament.

The temporal dynamics of ultrashort laser pulses undergoing filamentary propagation are investigated with a real-time stereographic above-threshold ionization (ATI) phasemeter. The experimental setup is capable of measuring the pulse duration as well as the carrier-envelope phase distribution of pulses originating from a femtosecond filament, which is either truncated in length or fully propagated. Truncation, by means of a semi-infinite gas cell, allows to elucidate the nonlinear evolution and temporal dynamics of ultrashort laser pulses as a function of the propagation length.

Hodgkin's lymphoma RNA-transfected dendritic cells induce cancer/testis antigen-specific immune responses.

Cytotoxic T lymphocytes (CTL) can kill Hodgkin's lymphoma (HL) cells, and CTL have been used for the treatment of Epstein-Barr virus (EBV)-positive HL. For patients with EBV-negative HL, this strategy cannot be employed and alternative target structures have to be defined. In order to establish a system for the stimulation of HL-reactive T cells, we used dendritic cells (DC) as antigen-presenting cells for autologous T cells and transfected these DC with RNA from established HL cell lines.

Gradient enhanced third harmonic generation in a femtosecond filament.

The third harmonic generated during femtosecond filamentation in air is studied. By establishing a gradient from atmospheric pressure to vacuum conditions, we truncate the filament abruptly at defined positions. The introduction of the pressure gradient leads to an enhancement of the generated third harmonic radiation by 3 orders of magnitude.

Tracking spectral shapes and temporal dynamics along a femtosecond filament.

The spectral evolution of a high-intensity light channel formed by filamentation is investigated in a detailed experimental study. We also track the spatio-temporal dynamics by high-order harmonic generation along the filament. Both the spectral and temporal diagnostics are performed as a function of propagation distance, by extracting the light pulses directly from the hot filament core into vacuum via pinholes that terminate the nonlinear propagation.

Generation of high-order harmonics with ultra-short pulses from filamentation.

7-fs-pulses with 0.3 mJ are obtained after filamentation in argon and compression by double-chirped-mirrors. These pulses are used to generate high-order harmonics in a semi-infinite gas cell in different noble gases.