Q switch, electro optic q switch, BBO pockels cells

Q-switching can promptly switch in between creating extremely little or really high losses to the laser light beam. This tool is typically made use of in laser resonators to enable active Q-switching of lasers, producing short, extreme pulses with pulse lengths in the nanosecond array. The Q-switch can likewise be combined with the tilt tooth cavity to create pulses, however the optical switch’s specific requirements are likewise different.

Q switch

Acousto-optic Q-switch

The most typical sort of Q-switch is the acousto-optic modulator. As long as the acoustic wave is shut off, the transmission loss caused by the crystal or glass sheet is very tiny, but when the sound wave is switched on, the crystal or glass will create a strong Bragg reflection, and the loss produced by each pass has to do with 50%. Creates 75% loss. To generate acoustic waves, a digital chauffeur calls for RF power at 1W (or several watts in big aperture tools) and microwave frequency (RF) at 100MHz.

Lots of parameters require to be compromised in the gadget. As an example, a tellurium dioxide material with a really high electro-optic coefficient requires really little acoustic power however has a moderate damage limit. Crystalline quartz or fused silica can take care of high light strengths but need greater acoustic power (as well as RF power). The needed acoustic power is additionally associated with the tool’s aperture: high-power lasers call for big aperture tools, which likewise require higher acoustic power. The Q switch creates a lot of warm, so a water-cooling gadget is called for. At lower power levels, only transmission cooling is needed.

The changing speed (or inflection transmission capacity) is inevitably not limited by the acousto-optic transducer however by the acoustic wave rate and the light beam diameter.

To suppress representations from optical surface areas, anti-reflection layers are often required. There are likewise Q-switched energetic tools operating at Brewster’s Factor.


Tellurium dioxide (TeO2) crystal is an acousto-optic crystal with a high-grade variable as well as a neutrino detection crystal with dual beta degeneration attributes. Considering that the all-natural wealth of 130Te is 33.8%, it does not require to be concentrated, as well as the cost is reduced, so TeO2 crystal comes to be the front runner for the double beta degeneration resource.

Electro-optical Q-switching

Electro-optical Q-switch is a sort of Q-switch, also referred to as Pockels cells as well as electro-optical inflection cells.

The electro-optical Q-switching is a bit extra made complex in framework, requiring a high-voltage (4000V) circuit plus a high-speed back-voltage circuit. The output power of electro-optical Q-switching is larger, getting to tens of megawatts, as well as the pulse size can be pressed to about 10ns. On high-power lasers, electro-optical Q-switching is frequently made use of. In general, for high-performance lasers, electro-optical Q-switching is liked. Furthermore, due to the flexible control of electro-optical Q-switching, it is used in single-pulse lasers.

Q-switched integrated circuit lasers need extremely high switching rates, which require electro-optic modulators. Among them, the polarization state of light is changed by the acousto-optic effect (Pockels result). After that the polarization state modification is converted into loss modulation by using a polarizer. Compared with acousto-optic tools, it needs greater voltage (need to obtain nanosecond changing rate) yet no RF signal.


LGS (La3Ga5SiO14) is a multifunctional crystal trigonal system and also belongs to the exact same 32 factor group as quartz. It has 2 independent electro-optic coefficients equivalent to those of BBO crystals. LGS crystals have excellent temperature level stability, modest light damage threshold, and mechanical stamina. Its half-wave voltage is fairly high but can be changed by the facet proportion. Consequently, LGS can be used as a brand-new electro-optical crystal, which can supplement the deficiencies of DKDP as well as LN crystals, and appropriates for making Q-switches for medium-power pulsed lasers and also various other electro-optical tools.

Passive Q switch

Passive switches are saturable absorbers set off by the laser itself. Amongst them, the loss introduced by the Q-switch itself is extremely tiny. When sufficient power is stored in the gain medium, the laser gain will be above the loss. The laser power starts to raise gradually, as well as once the absorber reaches saturation, the losses reduce the web gain rises, and the laser power raises quickly to form brief pulses.

Cr4+: YAG crystals are usually utilized as passive Q-switches in passive Q-switched YAG lasers. Various other products are offered, such as doped crystals and glasses, and semiconductor-saturable absorption mirrors are especially appropriate for producing tiny pulse powers.

Co:Spinel Crystal

Co: Spinel

Co:Spinel crystal is a freshly developed product with an emission wavelength of 1.2-1.6 μm, which has been verified to be a really reliable passive Q-switch. It is extensively used in eye-safe Er: glass lasers (1.54 µm) as well as is confirmed on lasers with wavelengths of 1.44 µm as well as 1.34 µm. Co: MgAl2O4 (Co: spinel) has a high absorption cross-section, which enables Q-switching of Er: glass lasers (flash and diode laser pumped) without intracavity concentrating, ignoring excited-state absorption, leading to high Q-switching contrast, That is, the proportion of the first to saturable absorption signal is higher than 10.