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Related to non-linear optics

It is said that the relation between Polarization and Electric field becomes non linear when applied electric field is comparable to interatomic field. What is its physical meaning?
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0answers
24 views

Simple analog to second harmonic generation

I have been trying to explain second harmonic generation to my mum who is hopeless at physics. Does anyone know of a good simple analog for second harmonic generation? Preferably something that is ...
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1answer
18 views

Why is second harmonic Intensity periodic in coherent length?

Solving for the intensity of second harmonic generation we get that intensity is $sinc^2(\pi/2*L/L_{coherent})$. How is calculated that the intensity is periodic in L_{coherent} (coherent length, L ...
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1answer
43 views

Why does generating EUV frequency combs require femtosecond enhanced cavities?

When generating extreme UV (EUV) frequency combs using high-order harmonic generation, why does the harmonic generation step need to be inside a femtosecond enhanced cavity for the comb to work? More ...
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1answer
20 views

How to find Intensity from field of train of pulses?

Lets say there is process that emits a field $E$ every half cycle of a driving laser pulse (in particular, high harmonic generation). The total field is $$ E(t) = \cdots + ...
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1answer
37 views

Physical meaning of Phase matching

Can anyone help me understand what exactly is meant by phase matching? I want to know whether momentum can be conserved only under phase matching condition or phase matching condition ensures momentum ...
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0answers
48 views

The Nonlinear Schrodinger Equation (NLSE) [closed]

I am trying to show that the NLSE: $$\frac{\partial A(z,T)}{\partial z} = -i \frac{\beta_2}{2} \frac{\partial^2A}{\partial T^2} + i \gamma |A|^2 A$$ may be cast in the form: $$\frac{\partial ...
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0answers
29 views

Definition effective nonlinear coefficient (SHG)

For a course in Electro Optics I have to do a home assignment. Given is that the input field is a plane wave propagating at frequency $\omega$ in the $y$-direction and polarized in the $(x,z)$ plane. ...
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1answer
34 views

Optical Frequency Divider?

Is there an optical frequency divider that works to make 1064nm light from 532nm light? The opposite of KDP crystals?
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1answer
24 views

in fiber whats relation between nonlinear effects? [closed]

i only know when power light is more than threshold ,nonlinear is showed . why they called nonlinear?where characteristic is nonlinear,it is for me ambiguous. Self-Phase Modulation (SPM) ...
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1answer
58 views

Wave vector relation in nonlinear material

A light wave ($k_1,\omega_1$) travels in a medium of refractive index $n_1$ and then encounters a nonlinear medium ($n_2$) under the angle $\theta_1$. Snell's law tells us the wave's direction in the ...
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0answers
45 views

Experimental evidence for nonlinear electrodynamics

Has any experiment been conducted which shows that, above a certain threshold of field strength, electromagnetic interactions become nonlinear? If not, which field strength threshold is the one under ...
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1answer
37 views

Polarization in high energy vacuum non-linearity?

I heard that the vacuum becomes nonlinear at high energies. What is an intuitive explanation as to why this happens? For example, in classical optics non-linearitiy comes from material field ...
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1answer
8 views

Third-order dispersion in glass, direction influence

I have learned that the third-order dispersion $\chi$ is a tensor with 81 elements. Nevertheless in glass one only has four elements, which either can be $x$ or $y$ (in this case). Now there exist ...
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0answers
21 views

Phase matching type 2 in a uniaxial material

A uniaxial nonlinear material has the following refractive indices for a laser of wavelength 1000 nm and its second harmonic: $$\begin{array}{c|c|c|} & \text{1000nm} & \text{500nm} \\ ...
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1answer
30 views

What is beam confinement?

In the context of the propagation of an electromagnetic wave and optical vortex solitons, I came across the term "beam confinement". Particularly, beam confinement requires the amplitude of the ...
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1answer
169 views

Difference between photon upconversion and two photon absorption?

One can find in the wikipedia the following assertion: Upconversion should be distinguished from two-photon absorption However, it is difficult to tell the difference between both processes by ...
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1answer
38 views

Would optical signal processing still suffer from slew rate?

In electronics, analog signal processing/computation suffers from parasitic capacitance which leads to slew rate—which is the maximum change of voltage allowed, so handling super-high frequency ...
2
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1answer
41 views

What is the equation of motion for multiple simultaneous pressure waves in a medium? (In the context of stimulated Brillouin scattering)

My overall motivation is to derive the behavior of Brillouin scattering in a birefringent fiber. Brillouin scattering is a nonlinear interaction between light and sound. In classic Brillouin ...
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0answers
82 views

Numerical Calculation of the Second Harmonic Generation in the Nonlinear Media

Recently I am working on the Numerical Calculation of the Second Harmonic Generation in the Nonlinear Media. I refer to the Book ...
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0answers
80 views

Second harmonic generation - how does SHG spectrum and pulse differ from the fundamental?

I'm trying to learn about second harmonic generation (SHG) in nonlinear optics but can't seem to find a conclusive answer to the following questions. 1) If generating SHG using a pulsed laser source, ...
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1answer
118 views

Mechanism for visible light frequency mixing in storm clouds

So I know that when red and blue light (or the frequencies/wavelengths we percieve as such) hit our eyes with the correct proportions, our eyes and brains interpret that as the color purple. In ...
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2answers
403 views

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 ...
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0answers
32 views

What are the physical optical limitations photonic metamaterials can offer?

Modern technology has introduced new photonic metamaterials that can extend optical properties beyond what standard materials can offer. For example a negative index of refraction is now possible ...
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0answers
94 views

Higher order multipolar second harmonic generation in centrosymmetric materials

As is pointed in this question, second harmonic generation is forbidden in the bulk of the materials possessing centrosymmetry. In some papers it is said that in the dipolar approximation the SHG ...
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2answers
135 views

If photon-photon interactions are impossible, how are higher harmonics generated?

In nonlinear optics, it is a rather common process to use nonlinear materials to produce higher harmonics of an incident wave. About the mechanism of the generation of such higher harmonics, it is ...
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1answer
160 views

Problem with Beam Splitter Refraction

I made a beam splitter for a simple test, as shown in the images below: This was my expected ray trace: But it instead refracted light like this: Why did the splitter cause light to ...
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2answers
709 views

What does $g^{(2)}$ signify in quantum optics? And how to calculate it?

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 ...
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0answers
146 views

Why the Caustic of a circle is the most bright curve in the circle?

Caustic of a cirle is the envelope of light rays reflected by a circle, which is the most bright curve in the circle. But why? Here is the picture shows the Caustic of a circle.
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0answers
48 views

Categorization of electromagnetic solitons?

I've seen over the years several mentions of electromagnetic solitons that appear in the high-intensity regime (where vacuum polarization becomes important). Some of these are coupled with plasmas, ...
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2answers
346 views

Is there a mathematical equivalence between gravitational optics and quantum optics or are they mathematically incompatible theories?

I know that massive gravitational bodies will curve the path that light travels. I think that quantum optical mediums also bend light. I am still confused of whether quantum optical mediums actually ...
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2answers
91 views

Trouble understanding phase matching equation

consider a 2nd order non linear optical material, i.e. a material in which it holds that $ P = \epsilon_0 E + 2dE^2$. In the Born approximation, the non linear contribution to the polarization density ...
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1answer
34 views

How to block coupling between adjacent waveguides?

I have a number of nonlinear waveguides, say six. I don't want coupling between specific two waveguides. Other than keeping them large distance away, what are the other possibilities to ensure no ...
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4answers
3k views

“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 ...
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2answers
577 views

Why does a single mode fibre have a cutoff wavelength?

I earlier had a doubt based on ray theory that light must reflect and so all wavelengths should propagate through SMF. This Q/A Single-mode fibers and ray-theory of light does specify that we have to ...
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0answers
201 views

Cut angle for BBO type I SPDC

I am using an old BBO crystal, which is not designed for spontaneous parametric down conversion, to see whether I can generate converted photons of 800nm from 400nm. I used a photon avalanche detector ...
3
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1answer
136 views

Electron momentum distribution and wavefunction in momentum space

Does there exist any relationship between the electron momentum distribution used in above threshold ionization and the wave function in momentum space? In other words, starting with the wavefunction ...
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2answers
74 views

Why is there an $E^2$-term in the expression for the polarization density in nonlinear optics

In nonlinear optics the polarization density can be expressed as $$P_i=\epsilon_0(X_{ii}^{(1)}E_i+X_{iji}^{(2)}E_jE_i+\dots)$$ As far as I know, $P$ arises from the dipole moment in materials, and ...
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1answer
126 views

Is glass considered as a linear optical medium?

My research, which is mainly related to communication, involves the use of optical sources (mainly lasers). However, my background in photonics and optics is not yet solid, so my question might be a ...
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1answer
123 views

Topological phase in Laguerre-Gaussian transverse mode

Why is the topological phase in a Laguerre-Gaussian transverse mode is the sum of orbital angular momenta per photon, and why is it quantized?
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4answers
657 views

What's the difference between Raman scattering and second harmonic generation in crystal?

As far as I know, the Raman scattering is from the stokes and anti-stokes scattering that the laser light interact with molecular vibrations. So we know that ""laser light interact with molecular ...
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5answers
821 views

Is Kerr effect in glass observable?

If I apply high electric field to a glass piece can I observe Kerr effect to some extent or will it be too small for glass to observe with eyes? I want to perform simple experiment without any costly ...
0
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1answer
152 views

Polarization effects of second-harmonic generation (SHG)

In one of my labs, we were using an Nd:YAG at 1064 nm and we put it through a KTP nonlinear crystal to perform SHG. We noticed that before the crystal, the 1064 light was unpolarized, but the 532 ...
3
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3answers
115 views

Simple Experimental Laser Characterization Parameters Ideas?

I have 2 months to do a project on characterization of a laser parameter. We have typical optics lab equipment (DFB Lasers, oscilloscopes, random number generator, etc.). I was told to choose a laser ...
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0answers
30 views

Resource about Supercontinuum Generation in Fibers

I would like to consult a nice reference that explains the theoretical background of SC generation in optical fibers in detail but more or less self-contained. I would also like to have your opinions ...
3
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2answers
196 views

Third order optical mixing

It's pretty straight-forward to visualise second-order non-linear optical mixing processes in which two waves of frequencies $\omega_{1}$ and $\omega_{2}$ mix up to generate new waves of different ...
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0answers
82 views

Why do “virtual states” in Raman spectroscopy have absorbance profiles distinct from either the ground or excited states of an absorbing material?

Do virtual states in Raman spectroscopy have distinct and observable dipoles that can interact with and/or induce dipoles in other molecules (over extremely short femtosecond timescales)? This notion ...
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0answers
1k views

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 ...
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2answers
158 views

Max temperature that can be obtained from radiation source when nonlinear interaction with matter is important?

Using a black body radiation as furnace it is usually said that the max achievable $T$ is limited to the T of the source. So a source of 3000K can not be used to heat a body above 3000K. A long ...
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0answers
263 views

Optical Raytracing by using Adiabatic Hamiltonian Method

I'm looking into raytracing a Lüneburg Lens which is a gradient index (GRIN) optical element with a radially varying refractive index: $$ n(\rho)=n_0\sqrt{2-\left(\frac{\rho}{R}\right)^2}, ...