Mode-locking is a technique for producing extremely short laser pulses, on the order of picoseconds ([latex]10^{-12}[/latex] s) to femtoseconds ([latex]10^{-15}[/latex] s). It works by forcing the many longitudinal modes of the laser cavity to oscillate with a fixed phase relationship. This causes the modes to interfere constructively, creating a single, intense, ultrashort pulse circulating in the cavity.

















