Q-switch is an important optical element in laser optical system. It suppresses and generates laser pulses by blocking and non-blocking the reflection channel of light.When the attenuator is functioning, light which leaves the gain medium does not return, and lasing cannot begin. This attenuation inside the cavity corresponds to a decrease in the Q factor or quality factor of the optical resonator. A high Q factor corresponds to low resonator losses per roundtrip, and vice versa. The variable attenuator is commonly called a “Q-switch”, when used for this purpose.