Q-switched operation, or q-switching, is a technique used in lasers to produce short and intense pulses of light. The term "Q" in q-switching stands for "quality factor," which is a measure of the energy stored in the laser cavity compared to the energy lost per cycle. Q-switching temporarily increases the quality factor of the laser cavity, allowing energy to build up before being released in a short and powerful pulse.
Key features of Q-switched operation include:
Q-switch device: Q-switching involves the use of a q-switch device within the laser cavity. The q-switch can rapidly change the quality factor of the cavity from low (allowing continuous output) to high (preventing lasing).
Energy storage: While in the high-quality factor state, the laser medium accumulates energy. This is often achieved by pumping the laser gain medium to a high energy level.
Rapid switching: The q-switch is then rapidly switched to the low-quality factor state, allowing the stored energy to be released in a short and intense pulse of light.
Short pulse duration: Q-switched lasers produce pulses with durations in the nanosecond to picosecond range, resulting in high peak powers.
Applications of Q-switched lasers include:
Material processing: Q-switched lasers are used in applications such as laser marking, engraving, and micromachining.
Medical procedures: In dermatology and ophthalmology, Q-switched lasers are employed for tattoo removal, skin resurfacing, and eye surgeries.
Scientific research: Q-switched lasers are utilized in various research applications, including spectroscopy and nonlinear optics.
The ability to generate short, high-energy pulses makes Q-switched lasers valuable in applications that require precision and minimal heat damage to surrounding materials. The Q-switching technique allows for efficient control over the timing and intensity of laser pulses.