Questions tagged [non-linear-optics]
312 questions
20
votes
4 answers
"Lack of inversion symmetry" in crystal?
Apparently (first paragraph of this article) the lack of inversion symmetry is some crystals allows all sort of nonlinear optic phenomena.
Now. Does anyone know of an intuitive or just physical explanation as to why this is the case?
What does…
SuperCiocia
- 25,602
19
votes
2 answers
What is $g^{(2)}$ in the context of quantum optics? And how is it calculated?
I have been studying research papers on Quantum Optics and non-linear optics. I frequently come across the $g^{(2)}$ value. What does it signify? What is its importance? How to calculate it? And do the calculation methods vary? If yes, what…
AKSHIT KUMAR
- 379
17
votes
2 answers
What colour is an electron?
In order to explain the colour of an atom or molecule⁺, one considers the orbitals of the electrons surrounding it and the respective energy level differences. A single free electron does however not possess any "self-orbital", and thus no colour in…
Tobias Kienzler
- 6,950
17
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1 answer
Third-order susceptibilities of metals?
Can anyone point me to a source for measurements of the third-order nonlinear electric susceptibilities $\chi^{(3)}$ of various metals? Specifically in relation to the AC Kerr effect, so measurements of the second-order index $n_2$ would do as…
ptomato
- 4,354
16
votes
4 answers
Nonlinear optics as gauge theory
the widely used approach to nonlinear optics is a Taylor expansion of the dielectric displacement field $\mathbf{D} = \epsilon_0\cdot\mathbf{E} + \mathbf{P}$ in a Fourier representation of the polarization $\mathbf{P}$ in terms of the dielectric…
Robert Filter
- 4,341
13
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8 answers
Is it possible to create a mirror that redshifts light?
Mirrors are able to reflect light but are not perfect and after a number of reflections, light loses intensity.
However I wonder, during the reflection by a different type of mirror, could the light photons lose some energy and thus be red shifted…
Winston
- 3,276
11
votes
1 answer
Understanding the virtual states referenced in multiphoton absorption studies
The Heisenberg energy-time uncertainty tells us that we can have so-called virtual states between eigenstates as long as the lifetime of these states is at most:
$\tau = (\frac{h}{4 \pi E_v})$
Where $h$ is the Planck constant ($6.62607 * 10^{-34}…
RGrey
- 373
11
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1 answer
Do radio beams self-focus in the interstellar medium?
Summary: In a plasma, electromagnetic waves create a ponderomotive force that pushes electrons and ions out of the way. Thus, in an intense laser beam, electrons tends to move away from the areas where the beam is strongest. This changes the local…
Thorondor
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11
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1 answer
How does dynamic casimir effect generate correlated photons?
There is a recent paper on arxiv receiving lot of acclaim http://arxiv.org/abs/1105.4714
The authors experimentally show that moving a mirror of a cavity at high speeds produces light from high vacuum. The usual doubts about the experimental…
New Horizon
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10
votes
5 answers
Why is two-photon absorption a third-order non-linear process?
I've just started learning about non-linear optics where I could not understand why the two photon absorption is a $\chi^{(3)}$ process. The way I understand susceptibility is that the order of $\chi$ tells us the number of frequencies…
SS_1234
- 381
10
votes
1 answer
Nonlinear polarization (second and third order)
Why does second order nonlinear polarization occur only in crystal materials with a non-centrosymmetric crystal structure? (Nonlinear effects at crystal surfaces are an exception). Why does third order polarization occur in basically all media?…
Eliina
- 101
9
votes
1 answer
Complex part of second-order susceptibility in nonlinear optics
In optics, the absorption of photons by a material can be described by considering the material's susceptibility. For linear absorption (involving a single photon), we think about the imaginary part of the complex linear susceptibility,…
Liz Salander
- 422
9
votes
2 answers
Is it possible to have solid light?
Is it possible to have solid light?
If so, what would it be like?
Featherball
- 314
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7
votes
2 answers
Why does spontaneous emission takes place when considering electronic transitions as opposed to vibrational ones?
The are two very general statements that I cannot understand.
For electronic transitions in which dephasing is typically much faster than the radiative lifetime, spontaneous emission is the dominant emission process.
For the case of vibrational…
Capo Mestre
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7
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Why are non-linear optics called non-linear?
Looking at the wikipedia article on nonlinear optics you can see a huge list of frequency mixing (or multi-photon) processes. What makes these different from single-photon interactions?
More specifically, I do not understand the link with the…
mactud
- 917