Nobel Lecture: Generating high-intensity ultrashort optical pulses^*

Figure 1

Energy of photons is depicted as height. Of the visible colors, red photons have the least energy, violet photons the greatest energy, with green photons in between. The height of the ball held up by the photon compared to the height of the basketball net is equivalent to the comparison of photon energy with the energy that holds the electrons to the atoms.

Figure 2

Schematic of chirped pulse amplification showing that the power remains low in the amplifier because of the stretcher, but the power is very high at the output of the pulse compressor.

Figure 3

Demonstration of adding different wavelengths in a controlled manner leading to shorter pulses.

Figure 4

Demonstration of low signal gain being energy inefficient. The figure shows the output photon number of 8 having started with one photon at the input. The stimulated emission has left only 7 of the atoms deexcited and almost all the atoms still in the excited state. This energy would be wasted.

Figure 5

Schematic of a parallel grating optical pulse compressor. The figure demonstrates that the path length through the compressor is shorter for the red colors compared to the blue colors. Because of this path length difference, the blue colors that were lagging in the pulse catch up to the red colors yielding the shortest possible pulse duration.

Figure 6

In the left panel, the perturbative effect of multiphoton ionization is depicted. The electron gets sufficient energy from simultaneous absorption of multiple photons to escape from the potential well. In the right panel, the process of over-the-barrier ionization is shown. The interaction with the high-intensity light wave bends the potential energy wall over. If the light power is sufficiently strong, the well is bent as low as the electron energy level and the electron is free to escape for the duration of the half period of the wave.