1. Q switching innovation
The Q-switching strategy is an effective technique to obtain brief pulses with high power. The q value is an index to assess the quality of the optical resonator in laser– “quality element.” Q-switching modern technology, additionally called Q-switching innovation, is a modern technology that presses the continual laser output right into a narrow pulse, thus enhancing the peak power of the light by several orders of magnitude.
In the process of the Q, gain medium before storing enough power, preserving high cavity loss, the laser resonator laser at this time, because the limit is too high, does not generate laser shock, makes the upper degree population can be a multitude of buildup when built up to saturation value, the loss of the cavity quickly lowered to a very little worth, Consequently, in a short time, most of the power saved in the top level fragments is converted into laser energy, as well as a stable laser pulse output is created at the result end.
Q switching modern technology is primarily separated into active Q switching modern technology (acousto-optic Q switching and electro-optic Q switching) and easy Q switching technology.
2. Passive Q-switching
In passive Q-switching innovation, a saturable absorber (usually a strong saturable absorber, such as Gr: YAG) is embedded in the resonator of a laser, and its saturation absorption result is used to periodically control the loss of the resonator to get the pulsed light outcome.
At the start, the autofluorescence in the cavity is extremely weak, the absorption coefficient of the saturable absorber is large, the light transmittance is very reduced, and the cavity remains in a state of high loss, so the laser oscillation can not be created. Continue to operate with the light pump, the inversion of bit number to accumulate, and lumen fluorescence stamina unceasingly.
When the light intensity gets to a particular worth, the saturable absorber absorption saturation worth is instant “blanch,” and the result laser pulse, and afterward light area inside the cavity is decreased, saturable absorber restores absorption qualities, and afterward duplicates the procedure to obtain the pulse light outcome.
Typically utilized passive Q-switched crystals are: co: spinel, Cr: YAG, Cr: GSGG, V: YAG, Cr: YSO, and so on
3. Active Q-switching
(1) Acousto-optic Q switch
Acousto-optic Q switching technology describes the acousto-optic tool in the resonator. When there is no ultrasonic wave, the light beam can freely travel through the acousto-optic medium. The Q worth of the cavity is extremely high (reduced loss), which is very easy to generate laser oscillation. When there is an ultrasonic wave, the density of acoustic and optical medium modifications periodically brings about the routine adjustment of the refractive index and the deflection of the light beam. At this time, the Q worth of the resonator is very low (high loss), and the number of particles in the upper level gathers rapidly. Consequently, we can manage the loss in the cavity by managing the ultrasonic wave and then get the pulse light output.
Common acousto-optic Q crystals are: TeO2 and so forth
(2) Electro-optic Q switching
Electro-optic Q switching uses the crystal’s electro-optic impact to include an action voltage on the crystal to change the representation loss of photons in the cavity. A high voltage is applied to the crystal. At this time, the electro-optic Q switch is in the off state, the resonator is in the low Q state, and the system remains in the energy storage space state. When the number of inverted bits in the resonator reaches the maximum, the high pressure on the crystal is instantly removed, and the resonator is in a high Q state, forming a pulsed laser result.
Pockels Cells is the basic component of the electro-optic modulator
Generally utilized electro-optic Q crystals are: BBO, LiNbO3, LiTaO3(LT), KTP, and so on