Lasers differ not only with respect to wavelength or optical power from each other, but also in the way how the power is emitted. It is a relevant difference, if the power is emitted continuously (continuous wave operation - cw) or in form of pulses (long pulse, giant pulse / q-switched or mode-locked).
In case of pulsed operation with low pulse repetition rate the peak power of each single pulse is the critical value. If the repetition rate inceases, the avarage power needs to be taken more and more into consideration. Please note, that some lasers can be operated in different modes.
Summary of Laser Operation Modes / Pulse Duration
Operation Mode
Descrition
Typical Pulse Length
Continuous Wave D (cw)
… is the continuous emission of laser radiation.
< 0,2 s
Pulse Mode (I)
… is the short-term single or periodically repeated emission of laser radiation.
> 1 μs to 0,25 s
Giant Pulse Mode R (Q-switch)
… is like pulsed mode, but the pulse length is very short.
1 μs bis 1 ns
Mode Locked M
… is the emission of laser radiation with all the energy stored in the laser medium released within the shortest possible time.
