Medically reviewed by Dr Sin Yong · Last reviewed · 3 min read
Published 13 October 2026 · Reviewed by Dr Sin Yong
Q-switched laser is a laser in which a shutter, the Q-switch, releases stored energy as a single pulse of about a billionth of a second, a nanosecond, commonly at 532 and 1064 nm. Q-switched lasers fragment pigment and tattoo ink so the body can clear them, but with more photothermal, heat-based contribution than a picosecond laser, whose pulses are roughly a thousand times shorter. It is the older generation; neither is a brand or a treatment plan.
Key facts
Pulse width
About one billionth of a second (nanosecond)
Mechanism
Fragments pigment with a mix of pressure and heat; the spread of heat is what inflames surrounding tissue
Wavelengths
532 nm for superficial pigment, 1064 nm for deeper pigment and darker skin
Still used for
Low-fluence 1064 nm toning across diffuse tone; nanosecond emissions sit alongside the picosecond mode on the DEKA TORO
Where it fits
The difference between Q-switched and picosecond lasers is pulse width, and pulse width changes the mechanism: a pulse shorter than the time a pigment particle takes to pass heat to its surroundings shatters it by a pressure wave with little heat spreading outward, while a nanosecond pulse heats the particle and some of the skin around it. The comparison is set out on pico vs Q-switched laser. In Dr Sin Yong's practice the DEKA TORO used for T2 Frax Radiance carries 532 and 1064 nm nanosecond emissions alongside its 785 nm picosecond emission, so the choice is made per mark and per visit. Q-switched toning keeps a role in low-fluence 1064 nm work for diffuse tone, with a stopping point; the newer class is defined under picosecond laser and the main platform on pico laser.
Frequently Asked Questions
It is a difference in delivery, not a verdict. Nanosecond pulses leave more heat in the skin, which matters for post-inflammatory hyperpigmentation in Fitzpatrick III to V skin, but fluence, spot size, wavelength and interval still decide the outcome on either pulse width.
In low-fluence 1064 nm toning for diffuse tone and brown marks after acne, yes, and not on an open-ended schedule. Discrete sun spots and freckles are usually treated with the picosecond emission instead.
References
Torbeck RL, Schilling L, Khorasani H, Dover JS, Arndt KA, Saedi N. Evolution of the picosecond laser: a review of literature. Dermatol Surg. 2019;45(2):183-194. doi:10.1097/DSS.0000000000001697. source
