Table of Contents
Types and Principles of Ultrafast Lasers
Ultrafast lasers emit ultrashort pulses with a duration of femtoseconds or picoseconds. These types of lasers and their applications are researched in the field of ultrafast laser physics and ultrafast optics. Ultrafast lasers are highly useful in a number of scientific applications as the duration of the optical pulse approaches the timescale of atomic processes. These lasers provide new opportunities for observation because they deliver the energy very quickly. Picosecond lasers and femtosecond lasers belong to the category of ultrafast lasers.
Picosecond Lasers and Their Applications
Picosecond lasers emit optical pulses with a duration of 1 or some picoseconds. Most often, mode-locked lasers provide ultrashort pulses. For example, a mode-locked Nd:YAG can generate 10 picosecond optical pulses. Picosecond fiber lasers need to be mode-locked to provide a high repetition rate and a short pulse duration. Other ultrafast picosecond lasers include Q-switched lasers and laser diodes.
Picosecond lasers and picosecond fiber lasers are used in various cosmetic procedures, like tattoo removal, in microfabrication, cutting of transparent materials, semiconductor manufacturing, range-finding, and biomedical applications, like ophthalmic surgery, and more.
Femtosecond Lasers and Their Applications
Femtosecond lasers emit optical pulses that are below 1 picosecond. The typical duration that femtosecond lasers provide is between 30 fs and 30 ps. The short pulses that are produced by these lasers are most often achieved by passive mode locking. Ultrashort duration of pulses is common among ultrafast fiber lasers that offer pulse durations of 50 to 500 fs. Femtosecond fiber lasers are, in most cases, mode-locked. Fiber solutions are cost-effective, but require extensive design efforts due to technical challenges.
Femtosecond lasers are widely used in material processing. A short pulse of a laser reduces the “heat-affected zone,” which maximizes the precision of material processing by reducing undesirable effects like splatter and resolidification of melted material. Other fields of application of femtosecond lasers are tissue modification and microsurgery, medical device manufacturing, biomedical imaging, and spectroscopy.
Ultrafast lasers have been developing for three decades and are expected to develop further in the future. The main features that are expected to improve are pulse frequency, power levels, and manufacturing costs.