The amplified laser pulses are then recompressed into high-intensity ultrashort pulses (see Fig. By deliberately broadening an ultrafast pulse using a pulse stretcher, the peak power is substantially reduced, making it possible to amplify the pulse to even-greater energies without nonlinear pulse distortion or damaging of the gain medium or the surrounding optical elements. Pulse compression is an essential part of ultrafast laser setups, as most high-energy ultrafast systems rely on this in a process called chirped-pulse amplification (CPA). Ultrafast lasers produce ultrashort laser pulses through mode-locking, which occurs when light waves are emitted coherently through in-phase superposition and contain a large quantity of modes (see Fig. Dispersion compensation in ultrafast systems These multipass cells allow for maximum pulse compression and are more compact, cost-effective, and easier to align than previous approaches. This issue can be solved through creating a multipass cell using one or more concave dispersive mirrors with through-holes. However, a large number of reflections is required to compensate for high GDD, requiring the use of a cumbersome system of many flat mirrors. Optical components with a negative group-delay dispersion (GDD), such as dispersive flat mirrors, are often used to balance the positive GDD of most optical media. Ultrafast lasers have an inherently wide wavelength bandwidth because of their short pulse duration, which leads to significant chromatic dispersion in optical media. 1 In medical applications such as laser surgery, ultrafast laser sources result in decreased trauma and less anesthetics and sterilization required. Benefits for materials processing include better dimensional tolerances, a reduction of postprocessing steps required, and minimized damage to surrounding areas. The short pulse durations and impressive peak powers of ultrafast lasers make them highly advantageous for a range of applications, including precise materials processing, micromachining, biomedical systems, communications, and nonlinear microscopy and imaging.
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