A passive Q switch is a gadget that can achieve Q switching by benefiting from the fact that the passage of optical material depends on the laser’s strength at a certain wavelength. The laser freeze linker mainly creates saturated absorbent crystals in passively Q-switched crystals. With increasing light intensity, the absorption coefficient of saturated absorption crystal decreases. When the saturation value is reached, the loss (Q-value) in the laser cavity is modulated, as well as the pulse.
Some passive Q-switching crystals are listed below:
1. Co:Spinel crystal
Co:Spinel crystal, called cobalt spinel, is a freshly created material. Its sending out wavelength range is 1.2–1.6 μm, which has actually been verified to be a really effective passive Q-switched switch. It is widely utilized in the eye-safe Er:glass laser (1.54 µm) and also has been verified in lasers with wavelengths of 1.44 µm and also 1.34 µm.
Co:MgAl2O4 (Co:spinel) has a high absorption cross-section, making it possible for Q switching of Er: glass lasers (flash and also diode laser pumps) without cavity focusing. The negligible excited state absorption results in a high comparison ratio of the Q switch. That is, the proportion of the initial to saturated soaked up signal is higher than 10.
The primary attributes of Co: Spinel crystal:
- 1.3 to 1.6 um, within the low optical loss range
- High damage threshold
Main applications of Co: Spinel crystals: passive q-switched @ 1.54 microns
2. V:YAG crystal
V: YAG crystal, the Chinese name for vanadium-doped yttrium aluminum garnet, is a relatively new crystalline product. Ideal for 1.06 to 1.44 μm laser emission, particularly for 1.3 μm Nd lasers. The absorption peak cross-section of the excited state is not evident near the absorption top of 1300 nm.
This product has outstanding optical, mechanical, and thermal properties. It can be created using the Czochralski approach. V:YAG can be utilized in Nd:YAG, Nd:YAP, Nd:KGW, Nd:YVO4, and other active media to obtain the passive Q-switched laser with a portable framework and excellent performance.
V: YAG crystal Main qualities:
- High-ground state absorption
- Not apparent excited state absorption
- Q switch high comparison
- Good optical properties, mechanical residential properties as well as thermal buildings
- Ultraviolet resistant high damage limit
V: YAG Main application:
- Utilized in laser rangefinder
- Laser radar
- The passive tuning Q laser LIBS system
3. Cr4+:YAG crystal
Cr:YAG crystal, Chinese name chromium doped yttrium aluminium garnet, is an ideal product for Q switching of laser (Nd:YAG and also various other doping Nd or Yb) with wavelengths from 0.8 to 1,2 μm. A significant function of Cr4+:YAG is its high damage limit of 500-1000 MW/cm2. Its absorption band expands from 800 nm to 1200 nm and also reaches its top at regarding 1060nm, with a large cross-sectional location of absorption height.
Cr: YAG highlight:
- 500-1000 MW/cm2 high damage limit
- Extremely secure chemical and dependability
- Good thermal conductivity, lengthy service life
- Small passive Q switch
- Very easy to operate
Cr: YAG Main application:
- Made use of for laser range finder, LIDAR and LIBS passive tuning Q laser system
- Need a brief pulse laser system.
4. Cr:YSO
In 1991, it was discovered that Cr:YSO( pure tetravalent chromium collection) solid-state saturable absorbing could be utilized for laser applications.
In 1993, Chen et al. used Cr:YSO solid-state saturable absorber to efficiently act upon a 694.5 nm ruby laser,
The crystal’s wide-band absorption spectrum (peaking at 390 nm, 595 nm, 695 nm, and 750 nm) prolongs from the visible region to the near-infrared area, making it a good switch for lots of lasers.
5. Cr:GSGG
Cr4+:GSGG can be used as a passive Q-switch in the 1.06 μm band. Compared with the conventional Cr4+:YAG passive Q-switched crystal, Cr4+: GSGG have the complying with advantages:
- In the visible component is transparent (calibration) as well as is extra helpful to the laser light path.
- In 1.06 um band have a greater absorption coefficient. At the same time, it also has a solid ability for anti-irradiation.
