In the case of using gratings as dispersive elements, tilting the grating(s) changes the individual path lengths of different spectral components. The spectrally separated and amplified laser pulse is then routed through a pulse compressor with additional dispersive elements that recombine the frequency components back into a single laser pulse. First, the laser pulse is split into its spectral components in a pulse stretcher using one or more dispersive elements. CPAs are used to amplify ultrashort laser pulses safely, as their high peak powers would cause rapid and catastrophic damage in traditional amplifier designs.

Laser pulse compression is also employed in chirped pulse amplifiers (CPAs).

This is possible using prisms or gratings. Linear laser pulse compression depends on optical dispersive components that act as temporal delay lines for individual frequency components. The spectrally broadened laser pulse is usually chirped, and must be temporally compressed by means of linear laser pulse compression. In nonlinear laser pulse compression, the laser pulse first passes through a nonlinear medium which spectrally broadens the pulse through a nonlinear interaction such as self-phase modulation. Generally, you can distinguish between linear pulse compression and nonlinear pulse compression. The physical principle behind laser pulse compression is a delay of particular frequency components in the pulse spectrum so that the overall pulse is temporally recompressed. That means that ultrashort pulses offer plenty of frequencies that can be delayed against each other due to dispersion, thus broadening the pulse length. The shorter the temporal length of the pulse, the broader the frequency spectrum. The laser pulses from ultrafast lasers consist of a broad range of optical frequencies. Laser pulse compression enables you to counteract the stretching of the pulse length to regain or even shorten the original pulse length. In case of wave packets such as laser pulses, it leads to a temporally stretched pulse, depending on the dispersion strength of the optic material. This results in a time delay between the wavelength parts. In general, the longer wavelengths propagate with higher speed of light than the shorter wavelengths in the material. In materials of optical components such as lenses or fibers, the speed of light is dependent on the wavelength of the passing light. What stretches an ultrashort laser pulse?

Laser pulse compression is a well-known method to reduce the duration of a laser pulse in order to recompress the stretched pulse length, as after amplification of light in a chirped pulse amplifier (CPA). This particularly affects ultrashort lasers as it becomes more apparent at extremely short pulse durations. Laser pulses are stretched differentially by wavelength in the time domain when passing through optical materials.

Laser pulse faster than light