A Q switch is an optical component with which optical pulses can be generated in the nanosecond range. In terms of function, a Q switch works as a switchable attenuator. It attenuates the laser beam passing through it to a greater or lesser extent and thus generates the intensity changes of the optical pulses.
Q-switches are used in laser resonators to generate ultrashort optical pulses. There are acousto-optic Q-switches, which are equivalent in design to acousto-optic modulators, Acoustic Optical Modulators( AOM), and in which the intensity change is due to the attenuation change that occurs when the laser beam is deflected. Depending on the crystal material, more or less acoustic pressure is required for the deflection.
In addition to the acousto-optical Q-switches, there are also the electro-optical and the passive Q-switches. Electro-optical modulators can be used as electro-optical Q-switches. With these modulators, the polarization of the laser beams can be influenced by electro-optical effects. Compared to the acousto-optical Q-switches, these Q-switches require much higher voltages, which also have to be switched with nanoseconds.