non-linear optics (NLO)

A subfield focusing on non-linear behavior of light in a non-linear system. For example, two-photon absorption follows a non-linear curve dependent on excitation light intensity.

See also: multiphoton microscopy , two-photon excitation , three-photon excitation , second harmonic generation microscopy , third harmonic generation microscopy , Raman scattering

Learn more:

Multiphoton Microscopy

Mode-locked pulsed lasers are used for deep tissue imaging and optical sectioning.