A Q-switched laser is a laser that makes use of active or passive Q-switching innovation to produce high-energy pulses of light. Typical applications of such lasers are in product handling (e.g., cutting, drilling, laser noting), pumping nonlinear frequency conversion tools, varying, and remote noticing.
Q-switched lasers can be continuously pumped or pulsed pumped, for instance, from a flash lamp (especially for low pulse repetition rates). The gain tool should have a long top power state lifetime for constant pumping to attain sufficiently high kept power without losing energy as fluorescence does. Regardless, the saturation power should not be too low, as this would certainly trigger the gain to be large, making it more difficult to suppress a premature laser. The latter problem is specifically likely to accompany fibre lasers. On the other hand, high saturated shot amounts can make efficient power extraction difficult.
Sort of Q-switched laser
Actively Q-switched solid-state laser
The most common type is an active Q-switched solid-state laser. Strong state gain media have good energy storage capacities. Volume lasers enable huge mode areas (hence higher pulse energy and peak power) and much shorter laser resonators (compared to fibre lasers, for instance). The laser resonator contains an active Q switch – a light modulator, usually an acoustic-optical Q switch.
For wavelengths in the 1μm spectral range, the most typical pulsed lasers are based on neodymium-doped laser crystals, such as Nd: YAG, Nd: YVO4, or Nd: YLF, although ytterbium-doped laser gain media can also be made use of. A reduced pulse repetition rate (lower than the inverted top power state lifetime) can achieve the greatest pulse energy and the shortest pulse duration at the cost of minimized average result power. A slightly bigger Nd: YAG laser with a 10-watt pump source, such as a diode rod, can attain a pulse power of several millijoules. YVO4 is appropriate for brief pulse durations, high pulse repeating prices, or low-pump power procedures. Q-switched lasers with longer discharge wavelengths are normally based on erbium-doped laser gain media.
Passive Q-switched laser
The passive Q-switched laser consists of a saturated absorber (passive Q-switch) instead of a modulator. Normal pulse sequences can be acquired for continual pumping, where the timing of the pulses can not usually be precisely managed by outside means, as well as the pulse repetition price boosts as the pump power boost. Cr: YAG crystal is one of the most generally used saturable absorbers for 1-μm lasers.
Passive Q-switched microchip lasers have specifically compact Settings. Such lasers normally emit pulses of power ranging from a nanojoule to a couple of microjoules, with an expected power outcome of tens of milliwatts and repetition prices ranging from a couple of kilohertz to a couple of megahertz.
Cr: YAG crystal
Cr: YAG crystal is an extremely outstanding passive Q switching material with many advantages, such as easy-to-achieve high pulse rep price as well as peak output power, low saturation light intensity, high doping focus, huge absorption cross-section, no degradation phenomenon, stable photochemical properties, high damages limit, long life, easy to use, excellent thermal conductivity.
The difference between passive as well as active Q-switched lasers
The ordinary outcome power of passively Q-switched lasers is much more minimal than that of energetic Q-switched lasers since the saturable absorber dissipates some energy, restricting thermal impacts. Note that saturable absorbers normally have unsaturated losses, which usually increase the dissipated power much past what is inevitable in concept.
Particularly, some smaller-sized Q-switched lasers and lasers with longer resonators, including an optical filter, such as a volumetric Bragg grating, operate in a uniaxial resonator setting. This results in a pure time form and a little optical bandwidth, typically limited by the pulse period. Other lasers oscillate in multiple cavity modes, which leads to a mode-jumping result: the result optical power is modulated to a frequency that is an integer multiple of the cavity round-trip frequency.
Application of Q-switched laser
Q – switched laser has a wide variety of applications. Some instances:
- 1. Laser product handling, such as laser cutting, laser boring, laser marking, laser pattern
- 2. Laser rangefinder
- 3. Lidar for 3D imaging
- 4. Laser-induced breakdown spectrum
- 5. Medical applications, such as dermatology and tattoo removal
- 6. Nonlinear frequency conversion pumping devices, such as pulsed optical parametric oscillators
- 7. Fluorescence spectrum