抄録
Mode-locking technique of lasers has its long history starting on quite early days of the advent of lasers. Pulse durations obtainable from mode-lock lasers were constantly shortened and reached femtoseconds today, roughly one-millionth from nano-second pulses at its beginning. In this tutorial review article, first, basic concept of mode-locking of lasers are described as its introduction, then putting emphasis on the topic of reducing the pulse duration, mode-lockings of solid-state lasers are mainly discussed. Control of the dispersion and the self-phase modulation inside the resonator, which is a key factor for obtaining ultra-short pulses, is described in detail.
