Full text loading...
Schematic layout of a fs pump-probe microscope. (a) Polarizing beamsplitters (PBS) are used to split the laser beam into pump and probe arms (PBS1) and vary the pump energy (PBS4 and a plate) measured with a photodiode PD1. PBS2 and PBS3 are used to adjust probe beam polarization for sample illumination in reflectivity mode (not discussed here) and beam diagnostics (PD2). Filter1 is a long-pass IR filter. Time-resolved transmission image of the spatial plasma distribution recorded in fused silica for a time delay of without the slit (b) and with a horizontal slit width (c) at the processing depth of with pulse energies of 0.25 and , respectively. (d) Transillumination image of a femtosecond laser-written waveguide under similar conditions as in (c) and the corresponding guided mode at (e).
Transient transmission images recorded in bulk Er:Yb codoped phosphate glass at depth with circularly polarized TL pump pulses of energy (at the sample site) [(a)–(c)] and stretched pulses [(d)–(f)] at several time delays , i.e., in (a) and (c), for (b) and (e), and for images (c) and (f). In all images the laser beam impinges from the left.
Time-resolved spatial distributions of laser-induced plasmas with circularly polarized TL pump pulses as a function of the processing depth. The pump pulse energy was fixed to at the sample site. The absence of filamentation at shallow depths, i.e., , is shown in (a) and (b) at different time delays . Multiple filaments are clearly visible at depth in (c) and (d). In all images the laser beam impinges from the left.
Plasma emission images recorded for various pump pulse durations under the same experimental conditions, i.e., pump energy, processing depth. In (a)–(c) plasma emission images for horizontal polarization are shown, whereas (d)–(f) present plasma emission images for circularly polarized laser with the same values of as in (a)–(c).
Article metrics loading...