Passive Q-switching crystals


Passive Q-switching crystals

A Passive Q switch is a device that can accomplish Q switching by making use of the fact that the transmittance of optical product depends upon the la

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A Passive Q switch is a device that can accomplish Q switching by making use of the fact that the transmittance of optical product depends upon the laser intensity at a particular wavelength. The laser freeze linker generally produces saturated absorptive crystals in passive Q-switched crystals. The absorption coefficient of saturated absorption crystal reduces with the rise of case light strength. When the saturation worth is reached, the loss (Q value) in the laser cavity is modulated, and also the pulse is discharged.

Some passive Q-switching crystals are listed here:

3. Cr: YAG

Cr: YAG crystal, Chinese name chromium doped yttrium aluminium garnet, is a suitable 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 notable feature of Cr4+: YAG is its high damages threshold of 500-1000 MW/cm2. Its absorption band prolongs from 800 nm to 1200 nm and also reaches its optimal at about 1060nm, with a huge cross-sectional location of absorption optimal.

Cr: YAG crystal Main features:

  • 500-1000 MW/cm2 high damages threshold
  • Very steady chemical and dependability
  • Excellent thermal conductivity, lengthy life span
  • Small passive Q switch
  • Simple to run

Cr: YAG crystal Main application:

  • Used for laser range finder
  • LIBS passive adjusting Q laser system
  • Require a brief pulse laser system.

Co: Spinel

Co: Spinel crystal, called cobalt spinel, is a recently created product. Its giving off wavelength range is 1.2-1.6 μm, which has shown to be an extremely efficient passive Q-switched switch. It is widely used in the eye-safe Er: glass laser (1.54 µm) and also has actually been verified 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 contrast ratio of the Q switch. That is, the ratio of the first to saturated taken in signal is more than 10.

The primary features of Co: Spinel crystal:

  • 1.3 to 1.6 mu m within the scope of the reduced optical loss
  • High damage threshold

Main applications of Co: Spinel crystals: passive q-switched @ 1.54 microns.


V: YAG crystal, the Chinese name vanadium-doped yttrium aluminium garnet, is a relatively brand-new crystalline product. Appropriate for 1.06 ~ 1.44 μm laser exhaust, specifically for 1.3 μm Nd laser. The absorption peak cross-section of the excited state is not noticeable near the absorption peak of 1300 nm. This product has exceptional optical, mechanical and thermal residential properties. It can be produced by the Czochralski technique.

V: YAG crystals can be utilized in Nd: YAG, Nd: YAP, Nd: KGW, Nd: YVO 4 and also other energetic media to obtain the passive Q-switched laser with portable framework and also outstanding efficiency.

V: YAG crystal Main characteristics:

  • High-ground state absorption
  • Not noticeable ecstatic state absorption
  • Q switch high comparison
  • Excellent optical homes, mechanical residential or commercial properties and thermal buildings
  • Ultraviolet resistant high damages threshold

V: YAG crystal Main application:

  • Utilized in laser rangefinder
  • Laser radar
  • The passive adjusting Q laser LIBS system


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

In 1993, Chen et al. made use of 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 visible area to the near-infrared region, making it an excellent switch for several lasers.


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 crystal has the following benefits:

  • In the noticeable component is transparent (calibration) and is a lot more beneficial to the laser light course;
  • In 1.06 mu m band have a better absorption coefficient. At the same time, it also has a strong capability for anti-irradiation.