5 Derivation of second harmonic generation.3 Second harmonic generation microscopy.It is a special case of frequency multiplication. Generating the second harmonic, often called frequency doubling, is also a process in radio communication it was developed early in the 20th century, and has been used with frequencies in the megahertz range. In their extensive evaluation of Maxwell's equations at the planar interface between a linear and nonlinear medium, several rules for the interaction of light in non-linear mediums were elucidated. The formulation of SHG was initially described by N. Famously, when published in the journal Physical Review Letters, the copy editor mistook the dim spot (at 347 nm) on the photographic paper as a speck of dirt and removed it from the publication. They sent the output light through a spectrometer, recording the spectrum on photographic paper, which indicated the production of light at 347 nm. They focused a ruby laser with a wavelength of 694 nm into a quartz sample. The demonstration was made possible by the invention of the laser, which created the required high intensity coherent light. Weinreich at the University of Michigan, Ann Arbor, in 1961. Second harmonic generation was first demonstrated by Peter Franken, A.
![second harmonic generation second harmonic generation](https://ars.els-cdn.com/content/image/3-s2.0-B9780128035818024048-gr6.jpg)
It is a special case of sum frequency generation. Second harmonic generation, as an even-order nonlinear optical effect, is only allowed in mediums without inversion symmetry. Second harmonic generation (also called frequency doubling or abbreviated SHG) is a nonlinear optical process, in which photons with the same frequency interacting with a nonlinear material are effectively "combined" to generate new photons with twice the energy, and therefore twice the frequency and half the wavelength of the initial photons.
#SECOND HARMONIC GENERATION SERIES#
The three arrows show the Fourier series of the motion: The blue arrow corresponds to ordinary (linear) susceptibility, the green arrow corresponds to second-harmonic generation, and the red arrow corresponds to optical rectification. But because the electron is in an anharmonic potential energy environment (black curve), the electron motion is not sinusoidal. An electron (purple) is being pushed side-to-side by a sinusoidally-oscillating force, i.e.