Passive and active Q-switch

Passive and active Q-switch

Q switching modern technology

The Q switch strategy is an efficient technique to get brief pulses with high energy. Q worth is an index to examine the quality of the optical resonator in a laser (the “quality element”). Q-switching technology, also called Q-switching technology, is a modern technology that presses the continual laser result into a really slim pulse, therefore boosting the peak power of the light by several orders of magnitude.

In the process of the Q, gain medium before shopping enough power, preserving high cavity loss, the laser resonator laser currently makes the top degree populace a multitude of build-up, which, when accumulated to saturation value, quickly decreased to a very tiny value, thus, in a short time, a lot of the energy saved in the top degree fragments is exchanged for laser power, as well as a solid laser.

Q switching modern technology is generally divided into energetic Q switching modern technology (acousto-optic Q switching and also electro-optic Q switching) as well as easy Q switching modern technology.

The passive

In passive Q-switching technology, a saturable absorber (usually a solid saturable absorber, such as Cr:YAG) is set in the resonator of a laser, and its saturation absorption result is used to periodically manage the loss of the resonator to acquire the pulsed light output. At the start, the autofluorescence in the cavity is really weak, the absorption coefficient of the saturable absorber is huge, the light passage is extremely reduced, and the cavity is in a state of high loss, so the laser oscillation cannot be developed.

Continue to use the light pump, the inversion of fragment number to continuously gather lumen fluorescence strength, and when the light intensity reaches a specific value, the saturable absorber absorption saturation value was unexpectedly “blanch” and the output laser pulse, and after that light area inside the cavity is abated, saturable absorber restore absorption features, and then duplicate the procedure to obtain the pulse light result.

Typically used passive Q-switched crystals are: Co:Spinel crystal, Cr:YAG, Cr:GSGG, V:YAG, Cr:YSO, etc

Active Q switch

1) Acousto-optic Q switch

The acousto-optic Q-switching innovation describes the acousto-optic tool in the resonator. When there is no ultrasonic wave, the beam of light can freely pass through the acousto-optic tool. The Q-value of the cavity is extremely high (reduced loss), which makes it simple to generate laser oscillation.

When there is an ultrasonic wave, the thickness of the acoustic and optical tools are adjusted regularly, resulting in the routine adjustment of the refractive index and also the deflection of the light beam. At this point, the resonator’s Q value is extremely low (high loss), and the number of bits in the upper level is rapidly increasing. Consequently, we can manage the loss in the cavity by controlling the ultrasonic wave and, afterwards, get the pulse light result.

Typical acousto-optic Q crystals are: TeO2 and so forth.

2) Electro-optic Q switching

Electro-optic Q switching utilizes the electro-optic impact of the crystal to add a step voltage on the crystal to adjust the representation loss of photons in the cavity. A high voltage is put on the crystal; right now, the electro-optic Q switch is in the off state, the resonator is in the reduced Q state, and the system also remains in the energy storage space state. When the variety of upside-down particles in the resonator reaches its maximum, the high pressure on the crystal is suddenly eliminated, and the resonator remains in a high Q state, forming a pulsed laser result.

Commonly used electro-optic Q crystals are BBO, LiNbO3, LiTaO3 (LT), KTP, and so on.

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