Due to the requirement of phase-matching (see below), the generated second-harmonic field propagates dominantly in the direction of the nonlinear polarization wave. According to Maxwell's equations, this nonlinear polarization wave radiates an electromagnetic field with that doubled frequency. Due to the nonlinearity, the fundamental (pump) wave generates a nonlinear polarization wave which oscillates with twice the fundamental frequency. The physical mechanism behind frequency doubling can be understood as follows. Examples are lithium niobate (LiNbO 3), potassium titanyl phosphate (KTP = KTiOPO 4), and lithium triborate (LBO = LiB 3O 5). The article on nonlinear crystal materials lists a number of crystal materials, many of which are popular for frequency doubling. Figure 1: A typical configuration for frequency doubling: an infrared input beam at 1064 nm generates a green 532-nm wave during its path through a nonlinear crystal. In most cases, the pump wave is delivered in the form of a laser beam, and the frequency-doubled (second-harmonic) wave is generated in the form of a beam propagating in the same or a similar direction. This process is also called second-harmonic generation. half the vacuum wavelength) in the medium. This can give rise to the phenomenon of frequency doubling, where an input (pump) wave generates another wave with twice the optical frequency (i.e. How to cite the article suggest additional literatureĬrystal materials lacking inversion symmetry can exhibit a so-called nonlinearity (→ nonlinear crystal materials).
More specific terms: resonant frequency doubling, intracavity frequency doubling More general term: nonlinear frequency conversion Acronym: SHG = second-harmonic generationĭefinition: the phenomenon that an input wave in a nonlinear material can generate a wave with twice the optical frequencyĪlternative term: second-harmonic generation
0 kommentar(er)
