Summary of Short Pulse Generation

There are several ways of generating short pulses. One is based on mode-locking lasers which have gain media with a broad special range. While the first experiments relied on dye lasers or Nd YAG-lasers, the Ti Sapphire laser has now become the most attractive choice. Some of the most commonly used materials are listed in Table 6.1 and [756]. Laser pulses down to 4 fs have been demonstrated using Ken-lens mode-locking and chirped mirrors. 

Another method uses optical pulse compression in optical fibers, where the intensity-dependent part of the refractive index causes a frequency chirp and increases the spectral profile and the time duration of the pulse. Subsequent pulse compression, achieved with a pair of optical gratings or by using prisms, leads to a drastic shortening of the pulse. 

The path to the shorter and shorter pulses and higher peak powers achieved over the last few decades is illustrated on a logarithmic scale in Figs. 6.60 and 6.61. 

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