Welcome to our exploration of femtosecond laser mechanisms. A femtosecond laser is a remarkable device that generates extremely short optical pulses, each lasting only ten to the minus fifteen seconds. These ultra-short pulses are achieved through a sophisticated technique called mode-locking, which synchronizes multiple light frequencies within the laser cavity.
The femtosecond laser begins with a gain medium, typically a titanium sapphire crystal, which is excited by a pump laser. This pump energy elevates atoms to higher energy states, creating population inversion. The excited gain medium is placed within an optical cavity formed by two mirrors. Light bounces back and forth between these mirrors, passing through the gain medium repeatedly, where it gets amplified through stimulated emission.