Other operating modes (pulsed pumping)

There are other operating modes that are based on changes made to the pumping system rather than to the cavity. Naturally, when the pumping is pulsed, the laser emission is also pulsed. When there is only the amplifying medium in the cavity (no modulator), the operating mode is defined as gain-switching. Generally, pulses that occur during gain-switching are longer and weaker than Q-switched lasers.

In the case of diode lasers, pumping can easily be modulated by pulses of electric current. The gain in the semiconductor is directly correlated to the different modulations and the process is known as gain switching. The pulses can be very short (only several picoseconds) but the energy released is very low (of the order of only 10-12 J).