Passive Q-switching


A Passive Q-switching is a gadget that can accomplish Q-switching by capitalizing on the reality that the transmittance of optical material relies on the laser strength at a specific wavelength. The laser freeze linker primarily generates saturated absorptive crystals in passive Q-switched crystals. The absorption coefficient of saturated absorption crystal decreases with the rise of incident light strength. When the saturation value is gotten to, the loss (Q value) in the laser tooth cavity is modulated, and the pulse is discharged.

Some passive Q-switching crystals:

Co: Spinel

Co: Spinel crystal, called cobalt spinel, is a freshly created material. Its releasing wavelength range is 1.2-1.6 μm, which has proved to be a really efficient passive Q-switched switch. It is widely used in the eye-safe Er: glass laser (1.54 µm) and has actually been confirmed in lasers with wavelengths of 1.44 µm and 1.34 µm. Co: Mgal2o4( Co: spinel) has a high absorption cross-section, enabling Q switching of Er: glass lasers (flash and also diode laser pumps) without dental caries concentrating. The minimal excited state absorption causes a high comparison ratio of the Q switch. That is, the ratio of the preliminary to saturated absorbed signal is more than 10.

The major qualities of Co: Spinel crystal:

  • 1.3 to 1.6 mu m within the range of the low optical loss
  • High damages threshold

Main applications of Co: Spinel crystals:

  • Passive q-switched @ 1.54 microns


V: YAG crystal, the Chinese name vanadium-doped yttrium aluminum garnet, is a reasonably brand-new crystalline product. Suitable for 1.06 ~ 1.44 μm laser emission, particularly for 1.3 μm Nd laser. The absorption peak cross-section of the excited state is not noticeable near the absorption height of 1300 nm. This material has exceptional optical, mechanical and thermal homes. It can be created by the Czochralski technique. V: YAG crystals can be utilized in Nd: YAG, Nd: YAP, Nd: KGW, Nd: YVO 4 as well as other active media to get the passive Q-switched laser with small structure as well as excellent efficiency.

Main attributes:

  • High-ground state absorption
  • Not apparent thrilled state absorption
  • Q switch high comparison
  • Excellent optical residential or commercial properties, mechanical properties, and thermal buildings
  • Ultraviolet-resistant high damages limit

Main application:

  • Used in laser rangefinder, laser radar, and the passive adjusting Q laser LIBS system


Cr4+: YAG crystal, Chinese name chromium doped yttrium aluminum garnet, is an excellent 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 notable attribute of Cr4+: YAG is its high damage threshold of 500-1000 MW/cm2. Its absorption band expands from 800 nm to 1200 nm and reaches its height at about 1060nm, with a huge cross-sectional area of absorption optimal.

Main features:

  • 500-1000 MW/cm2 high damages limit
  • Highly steady chemical and also integrity
  • Excellent thermal conductivity, long service life
  • Small passive Q switch
  • Simple to run

Main application:

  • Made use of laser range finder, LIDAR as well as LIBS passive tuning Q laser system
  • Need a brief pulse laser system.


In 1991, it was discovered that Cr: YSO( pure tetravalent chromium series) solid-state saturable absorbing could be used for laser applications.

In 1993, Chen et al. utilized Cr: YSO solid-state saturable absorber to successfully act on a 694.5 nm ruby laser.

The crystal’s wide-band absorption spectrum (peaking at 390 nm, 595 nm, 695 nm, as well as 750 nm) extends from the noticeable area to the near-infrared area, making it a good switch for numerous lasers.


Cr4+: GSGG can be used as a passive Q-switch in the 1.06 μm band. Compared to the typical Cr4+: YAG passive Q-switched crystal, Cr4+: GSGG crystal has the complying with advantages:
The noticeable component is transparent (calibration) as well as is a lot more advantageous to the laser light course, In 1.06 mu m band have a higher absorption coefficient. At the same time, it additionally has a solid capability for anti-irradiation.

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