Laser is the light that is generated and amplified by the stimulated radiation, i.e., the light amplification by the stimulated radiation. It is characterized by excellent monochromaticity, very small dispersion, and high brightness (power). The three elements required to produce laser light are "excitation source", "gain medium", and "resonance structure".
Pulse
This is the mechanical form of a wave (electric/optical, etc.) that is emitted at the same interval.
Laser pulse
A laser pulse is a light pulse emitted by a laser that works in a pulsed manner. Simply put, it is like the work of a flashlight, where the button is closed all the time for continuous operation, and the switch is closed and turned off immediately for a "light pulse". Working with pulses has its own necessities, such as sending signals, reducing heat generation, etc. Laser pulses can be very short, such as "picosecond" level, which means that the pulse time is of the order of picoseconds, and 1 picosecond is equal to one trillionth of a second (10E-12 seconds).
Continuous laser
The laser pump source provides continuous energy to produce laser output over a long period of time, resulting in a continuous laser. The output power of continuous lasers is generally low and is suitable for applications requiring continuous laser operation (e.g. laser communication, laser surgery, etc.)
Pulsed laser
Pulsed mode of operation is a mode that works only once every certain time interval.
Pulsed lasers have larger output power and are suitable for laser marking, cutting, ranging, etc.
Common pulsed lasers: yttrium aluminum garnet (YAG) lasers, ruby lasers, sapphire lasers, neodymium glass lasers, etc. in solid state lasers. There are also nitrogen molecular lasers, excimer lasers, etc.
Giant pulse laser
Losses are artificially added to the cavity to make it greater than the gain of the working substance, when there is no laser output. However, under the continuous excitation of the pump source, the number of atoms on the energy level of the laser increases and a larger particle number inversion is obtained. If the peak power is defined as the energy of the pulse divided by the duration of the pulse (pulse width), then, with the removal of artificially added losses, a pulsed laser with a narrow pulse width and high peak power is produced in a very short period of time at a very fast rate, often called a giant pulse.
Continuous lasers, as the name implies, use laser output that is continuous in time. The output of pulsed lasers is discontinuous, commercially available to the order of a few femtoseconds, so pulsed lasers are often used to measure ultrafast physical processes. But continuous lasers also have the advantage that after frequency stabilization, you can get a very narrow line width, which can be used for laser ranging, fine spectroscopy.
The peak power difference between the two is a lot, continuous lasers in the better semiconductor lasers can do a hundred W scale, while pulsed lasers now femtosecond can do TW scale, the shorter the pulse width, the less the thermal effect, fine processing are more pulsed laser.
Peak power = single pulse energy / pulse width;
Average power = single pulse energy * repetition frequency.
The pulse width of a laser is for pulsed lasers or quasi-continuous lasers, and can be simply understood as the duration of the action of one laser pulse per emission or the duration of one laser pulse. The repetition frequency is the number of pulses emitted by the laser per second, e.g. 10 Hz means 10 laser pulses are emitted in one second. But the pulse width of each laser pulse varies from laser to laser, whether it is nanosecond or microsecond or millisecond.
