Nonlinear Optics - Pockels effect

  • #1
Greetings,

is anyone here familiar with nonlinear optics?

I want to know wether the Pockels effect only occurs in optically anisotropic media or not.
Of course, we need a medium with inversion symmetry ("non-centrosymmetric medium"), but I am not sure about the optical isotropy.
In an anisotropic medium, we have natural birefringence and the Pockels effect just modifies it. So the extraordinary and ordinary wave experience different refraction indices and the difference can be tuned by a voltage.
But will the Pockels effect induce birefringence in an optical isotropic medium, meaning a medium which does not have natural birefringence?

Here it states that the Pockels effect only occurs in anisotropic media:
http://electron6.phys.utk.edu/optics421/modules/m7/Non-linear optics.htm
But earlier in the text when they talk about χ2 term in the polarization, they say that this term is only non-zero in anisotropic media, which is wrong, since anisotropic and non-centrosymmetric is not the same. So they might be confusing the terms.

Wiki makes it sound like it also occurs in isotropic media like glasses and that it also can "produce Birefringence".
https://en.wikipedia.org/wiki/Pockels_effect

Best regards
SL
 

Answers and Replies

  • #2
Chandra Prayaga
Science Advisor
650
149
Greetings,

is anyone here familiar with nonlinear optics?

I want to know wether the Pockels effect only occurs in optically anisotropic media or not.
Of course, we need a medium with inversion symmetry ("non-centrosymmetric medium"), but I am not sure about the optical isotropy.
In an anisotropic medium, we have natural birefringence and the Pockels effect just modifies it. So the extraordinary and ordinary wave experience different refraction indices and the difference can be tuned by a voltage.
But will the Pockels effect induce birefringence in an optical isotropic medium, meaning a medium which does not have natural birefringence?

Here it states that the Pockels effect only occurs in anisotropic media:
http://electron6.phys.utk.edu/optics421/modules/m7/Non-linear optics.htm
But earlier in the text when they talk about χterm in the polarization, they say that this term is only non-zero in anisotropic media, which is wrong, since anisotropic and non-centrosymmetric is not the same. So they might be confusing the terms.

Wiki makes it sound like it also occurs in isotropic media like glasses and that it also can "produce Birefringence".
https://en.wikipedia.org/wiki/Pockels_effect

Best regards
SL
The Pockels effect is linear electro-optic effect. The dielectric tensor may be written, in the presence of an electric field:
εik = ε(0)ik + εiklEl
The last term is responsible for the Pockels effect. The tensor εikl is a polar tensor of rank three. It is certainly identically zero ( all components), not only in a medium with inversion symmetry, but also in an isotropic medium.
 
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  • #3
Thank you, this answers the question!
 

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