The distinction between passive and active Q-switching
1. Q-switching technology
The Q-switching method is reliable for acquiring brief pulses with high energy. Q worth is an index to examine the quality of optical resonator in laser– “quality aspect”. Q-switching innovation, also known as Q-switching technology, is a technology that compresses the constant laser result into a very narrow pulse, hence raising the peak power of the light by numerous orders of magnitude.
In the process of the Q, gain tool before shop sufficient power, keeping high cavity loss, the laser resonator laser right now as a result of the threshold is expensive, do not create laser shock, makes the upper-level populace can be a multitude of build-up when gathered to saturation worth, the loss of the cavity quickly reduced to a little value, Consequently, quickly, the majority of the energy stored in the upper-level bits is exchanged laser energy, and also a strong laser pulse outcome is produced at the outcome end.
Q switching modern technology is mainly separated right into energetic Q switching modern technology (acousto-optic Q switching and also electro-optic Q switching) and also easy Q switching innovation.
2. Passive Q-switching
In passive Q-switching innovation, a saturable absorber (generally a strong saturable absorber, such as Cr: YAG) is set in the resonator of a laser. Also, its saturation absorption impact is made used to regularly manage the loss of the resonator to acquire the pulsed light output. Initially, the autofluorescence in the cavity is very weak, the absorption coefficient of the saturable absorber is very large, the light passage is extremely reduced, and the cavity remains in a state of high loss, so the laser oscillation can not be formed.
Continue to work unceasingly with the light pump, the inversion of bit number to accumulate, and lumen fluorescence strength. When the light intensity reaches a specific worth, the saturable absorber absorption saturation worth is unexpected “blanch,” and the result is a laser pulse, and after that light area inside the cavity is abated, the saturable absorber restores absorption qualities, and then repeat the procedure to obtain the pulse light outcome.
Typically utilized passive Q-switched crystals are: cobalt 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 modern technology refers to the acousto-optic tool in the resonator. With no ultrasonic wave, the beam can easily travel through the acoustic-optic tool. The Q worth of the cavity is very high (reduced loss), which is very easy to create laser oscillation. When there is an ultrasonic wave, the density of acoustic and optical tool adjustments regularly brings about the routine adjustment of the refractive index and the deflection of the light beam. Right now, the Q worth of the resonator is extremely reduced (high loss), and the number of bits in the upper level accumulates rapidly. For that reason, we can manage the loss in dental caries by managing the ultrasonic wave and obtaining the pulse light result.
Usual acousto-optic Q crystals are: TeO2 and so on
(2) Electro-optic Q-switching
Electro-optic Q-switching uses the crystal’s electro-optic result to add an action voltage on the crystal to adjust the reflection loss of photons in the cavity. A high voltage is put on the crystal. Currently, the electro-optic Q button remains in the off state, the resonator is in the reduced Q state, and the system is in the energy storage space state. When the variety of upside-down bits in the resonator reaches the optimum, the high pressure on the crystal is instantly removed, and the resonator is in a high Q state, developing a pulsed laser outcome.
Frequently made use of electro-optic Q crystals are: BBO, LiNbO3, LiTaO3( LT), KTP, and so on
