A Passive Q-switching is a gadget that can achieve Q-switching by capitalizing on the fact that the passage of optical product depends upon the laser strength at a particular wavelength. The laser freeze linker mostly generates saturated absorptive crystals in passive Q-switched crystals. The absorption coefficient of saturated absorption crystal decreases with the rise of event light intensity. When the saturation value is reached, the loss (Q worth) in the laser dental caries is regulated, and also the pulse is discharged.

Some passive Q-switching crystals are listed below:

Co: Spinel

Co: Spinel crystal, named cobalt spinel, is a recently developed product. Its emitting wavelength array is 1.2-1.6 μm, which has actually proved to be a very efficient passive Q-switched switch. It is extensively used in the eye-safe Er: glass laser (1.54 µm) as well as has actually been validated in lasers with wavelengths of 1.44 µm as well as 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 diode laser pumps) without dental caries focusing. The negligible excited state absorption leads to a high comparison proportion of the Q switch. That is, the proportion of the preliminary to saturated taken-in signal is more than 10.

The primary qualities of Co:

spinel crystal :

1.3 to 1.6 mu m within the extent of the reduced optical loss

high damages limit

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 fairly brand-new crystalline material. Appropriate for 1.06 ~ 1.44 μm laser discharge, particularly for 1.3 μm Nd laser. The absorption optimal cross-section of the thrilling state is not noticeable near the absorption optimal of 1300 nm. This material has exceptional optical, mechanical, and thermal residential or commercial properties. It can be generated by the Czochralski approach. V: YAG crystals can be utilized in Nd: YAG, Nd: YAP, Nd: KGW, Nd: YVO 4, and other energetic media to acquire the passive Q-switched laser with the compact framework as well as outstanding efficiency.

V: YAG crystal Main features:

high-ground state absorption

not apparent excited state absorption

Q switch high contrast

good optical homes, mechanical homes as well as thermal buildings

ultraviolet immune high damages limit

V: YAG crystal Main application:

utilized 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 optimal product for Q switching of laser (Nd: YAG and also other doping Nd or Yb) with wavelengths from 0.8 to 1,2 μm. A significant attribute of Cr4+: YAG is its high damage limit of 500-1000 MW/cm2. Its absorption band extends from 800 nm to 1200 nm and reaches its top at concerning 1060nm, with a large cross-sectional area of absorption optimal.

Main features:

  • 500-1000 MW/cm2 high damages limit
  • extremely secure chemical and integrity
  • great thermal conductivity, long life span
  • portable passive Q switch
  • very easy to run

Main application:

  • utilized for laser range finder, LIDAR as well as LIBS passive tuning Q laser system
  • require a short-pulse laser system.


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

In 1993, Chen et al. made use of a Cr: YSO solid-state saturable absorber to effectively act upon 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) prolongs from the visible region to the near-infrared area, making it an excellent switch for numerous lasers.


Cr4+: GSGG can be made use of as a passive Q-switch in the 1.06 μm band. Compared to the conventional Cr4+: YAG passive Q-switched crystal, Cr4+: GSGG crystal has the adhering to advantages:

In the noticeable component is transparent (calibration) and also is a lot more helpful to the laser light course,

In 1.06 mu m band have a greater absorption coefficient. At the same time, it also has a solid ability for anti-irradiation.

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