The spectrometer records the spectrum of a nonlinear optical process such as second harmonic generation produced by the laser pulse.

Critical to developing said applications is actually understanding the physics of high harmonic generation.

Second harmonic generation has been demonstrated as a method to read data written into a poled polymer matrix.

Surface second harmonic generation is a method for probing interfaces in atomic and molecular systems.

It also plays an important role in second harmonic generation and many other nonlinear processes.

Second harmonic generation occurs in three types, denoted 0, I and II.

In biological and medical science, the effect of second harmonic generation is used for high-resolution optical microscopy.

In 1967 New et al. observed the first third harmonic generation in a gas.

Though the atom and the laser pulse interact in various ways, this is ignored here (see high harmonic generation instead).

The most common nonlinearity is second harmonic generation, where .