Laser terms glossary

Ablation rate

The ratio between the ablation depth and the energy used.

Average output power

Average optical power of the emission of the laser. It is particularly useful when dealing with pulsed laser. With continuous wave (CW) laser the avergae output power is the same as the peak power level.

Beam optical quality:

It is a measurement of the quality of the spatial energy distribution of a laser beam, 1 equals a perfect gaussian beam.


This is the transformation of an organic substance into carbon.

Fiber Bragg gratings 

Are reflective structures in the core of an optical fiber created by refractive index modification. It is the mechanism that allows the control of energy and spectral reflection in the laser cavities.

Laser operating frequency

For continuous emission, the laser is defined by its frequecy. For pulsed emission, it’s the laser pulse emission frequency that is taken into account.

Laser power

The power is given in units of Watt. Watt are defined as energy (joules) per unit of time (sec).

Laser wavelength 

Light has different colors, the laser wavelength is the color of the laser emission. Looking at laser light like an electromagnetic wave, the wavelength is the length of an oscillation.

Mode-Locked laser

Mode locking is a method to produce ultrashort pulses with lasers. It consists to place into the laser resonator an element, either active like an optical modulator, or passive like a saturable absorber, which causes the creation of an ultrashort pulse circulating in the laser cavity.

Peak output power 

For pulsed laser, each impulsion has a peak optical power. For continuous wave (CW) laser, the peak output power equals the average power of the laser.

Q-switched laser

Q-switching is a method for generating energetic short pulses from a laser by modulating the intracavity losses (quality factor Q). The technique is mainly employed for the generation of nanosecond pulses of high energy and peak power with fiber lasers and solid-state bulk lasers.

Spot size

Dimension of the focused laser beam onto the material surface. It is often a diameter and it's expressed in mm.