Questions tagged [non-linear-optics]

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Is it possible to optimally transmit solar radiation by a system of multiple optical fibers?

As we all know, if an optical fiber is designed with the right material and properly bent, light can be transmitted along the fiber with very little attenuation. Figure 1 shows the interaction of ...
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1answer
56 views

Why the Divergence of Electric field is Zero?

I am studying nonlinear optics, specifically the wave equation of nonlinear optical media. During the derivation I came across a point where the divergence of electric field was zero for a linear ...
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1answer
15 views

Does self-phase modulation generate new frequency components?

Not a physicist. Hope to clarify some conceptual issues I have with non-linear propagation of light through a medium, since I seem to be mixing up some very fundamental concepts. Specifically, I am ...
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1answer
26 views

Good books on electromagnetism for nonlinear optics

While reading books on nonlinear optics, I often come across concepts such as second-order susceptibility which is not covered in undergraduate E&M books like Griffiths. Are there any good E&M ...
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21 views

Derivatives of the propagation constant in optical fibers

In many books on nonlinear fiber optics, the Taylor series expansion of the mode-propagation constant $\beta$ is performed about a frequency $\omega_0$ at which a pulse's spectrum is to be centered. $\...
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14 views

Free Spectral Range versus Axial Mode Spacing?

I am doing research on micro cavity frequency combs and I've been trying to understand things like dispersion, Free Spectral range, resonance, and modes. I am looking at the definition of free ...
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14 views

Treatment of a light pulse moving from linear material A into non-linear material B

When I simulate the propagation of a pulse through a material without non-linear effects, I can use the non-linear schrödinger equation $$\partial_tE=\frac{i}{2k_0}\nabla^2E$$ with $k_0$ the wave ...
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6 views

Spiral waveguide for single-photon generation

I would like to ask about the advantage of a spiral waveguide for single-photon generation(using SFWM) compared to the SPDC process using bulk optics.
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1answer
21 views

Resources to learn about spontaneous parametric down conversion

I have recently begun working on a project where I will be modeling some experiment that uses SPDC to generate entanglement. However, I have not formally studied SPDC in any capacity. Is there any ...
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12 views

How to calclate Drude dielectric function vs probe energy from time resolve spectroscopy?

How can I calculate drude dielectric function vs probe energy (in eV) form differential transmittance vs delay time plots.
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26 views

How can I easily generate $\rm GaAs$ band structure?

Is there a program where I can easily generate $\rm GaAs$ band structure that shows lowest conduction band valleys?
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1answer
12 views

Definition of the polarization of a light beam due to the Kerr effect in fourier- and real space

During my literature review of linear and non-linear optics I found the linear polarization acting on light usually defined as $$\hat{P}=\varepsilon_0\chi^{(1)}\hat{E}$$ with $\hat{E}$ the electric ...
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11 views

Calculating the response function depending on the wavelength for a pulse propagation in time

When solving the non-paraxial pulse propagation $$\partial_z\hat{E}(\omega, z)=ik_z\hat{E}(\omega, z)+\frac{i\omega^2}{2\varepsilon_0c^2k_z}\hat{P}(\omega, z)$$ with $$E_0 = E_0(r, t, z)$$ the initial ...
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9 views

What is the typical efficiency/probability of success of producing a pair of photons in SPDC?

In Spontaneous Parametric Down Conversion process pump photons are broken up into pairs of photons. What is the typical probability of success or the efficiency of this process in practice?
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24 views

Marginal theorem in frequency-resolved optical gating (FROG)

In ultrashort laser physics, frequency-resolved optical gating (FROG) has been a standard method since a few decades to measure the temporal profile of an unknown pulse's electric field $E(t)$ via a ...
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0answers
18 views

Small values and Negative nonlinear susceptibility of a degenerate parametric amplifier

The quantum Hamiltonian of a degenerative parametric amplifier (DPA) is given by (taking $\hbar=1$ $$ \hat{H}=\omega\hat{a}^{\dagger}\hat{a}+2\omega\hat{b}^{\dagger}\hat{b}+\kappa\left(\hat{a}^{\...
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2answers
75 views

Optical Impedance Matching

Suppose you want to match optical impedances between a region of refractive index $n_1$ and a region of index $n_2$ and you want to expend a total distance $L$ in the impedance matching transition ...
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1answer
32 views

Differences in crystals used for SHG and OPO

SHG: second harmonic generation OPO: optical parametric oscillator As we know these are non linear cavities (optical cavities with non linear crystals in them along a part of light beam's path) used ...
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16 views

Maximum delay between n photons for multi-photon ionization

Given an IR laser with intensities that allow for a Keldysh parameter smaller than 1 in a given sample. I was wondering, what is the allowed timely separation distance between two IR photons such that ...
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27 views

Refractive index values of the solution less than that of the solvent. Why does that happen?

I have been doing an experiment for finding the third-order nonlinear susceptibilties of organic molecules using Degenerate Four-Wave Mixing (DFWM) at femtosecond regime. For the calculation of the ...
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61 views

Is it possible to solve those differential equations (with complex numbers)?

I'm trying to solve this equation, I don't know where to begin with. Is it feasible ? If so how should I solve it ? https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-20-7-7454&id=230426 https:/...
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1answer
38 views

What causes this high frequency “noise” in HHG spectra?

Looking at high harmonic spectra, one can often see that peaks corresponding to higher harmonics look more and more noisy and seem to be drowned out by the noise. For example, one such spectrum is ...
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1answer
71 views

Numerical simulation for spontaneous parametric down conversion

I want to numerically simulate the SPDC (spontaneous parametric down conversion) process. I have a basic background on nonlinear and quantum optics — I am a graduate student and just took a few ...
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27 views

Calculating the absorption cross-section for Helium in a strong oscillating external IR field -> AC Stark Shift (Autler-Townes Splitting)

I try to obtain the absorption cross-section for atomic helium, in a strong and oscillating IR field, for when a second - XUV - pulse is probing the system. I think the only way of doing this is to ...
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3answers
270 views

Why are there only odd harmonics at High Harmonic Generation?

I'm trying to understand why in High Harmonic Generation (HHG) the spectrum only consist out of odd multiples of the driving frequency. Many sources state "because of symmetry" but they do not clearly ...
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1answer
20 views

What is the difference between classical nonlinear optics and multiphoton physics?

Nonlinear optics is usually looked at through a classical lens for most purposes. I do a Taylor expansion of the material polarization in terms of light-field strengths and we can derive all the ...
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17 views

What is the physical significance of the elements of the nonlinear susceptibility?

I'm trying to understand the physical significance of the various elements of the nonlinear susceptibility tensors. My best attempt at understanding this is to say that the first index corresponds to ...
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83 views

Electromagnetic energy density in a nonlinear medium

The energy density associated with the electric field in a linear medium of permitivity $ \epsilon $ is given as $$ U = \frac{1}{2}\epsilon\left | E \right |^{2} $$ As Robert Boyd mentions in the ...
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84 views

Derivation of Hamiltonian in non-linear optics

Update 2: one half of the answer to this question can be found here and the other half in the second half of this post. I asked this question a few hours ago, but decided to re-post it because I ...
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1answer
93 views

Focusing a Gaussian beam into a nonlinear crystal

Boyd analyzes in his book (Boyd's book), section 2.10.3, the case of harmonic generation using a focused Gaussian beam and he mentions that an analytic solution can be evaluated for certain special ...
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1answer
154 views

How does optical “self-torque” make sense in terms of Maxwell's equations?

I saw an article in Science (arXiv:1901.10942) that describes "self-torque" of light. My understanding is that a series of ultrafast optical pulses with different angular momenta combine in some ...
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1answer
52 views

Why we use $i\hbar(\hat A -\hat A^\dagger)$ in Parametric Down-Conversion?

When we descirbe the degenerate parametric oscillator or the Parametric Down-Conversion, we can use the hamitonian: $$\hat{H}=\hat H_0+\hat H_{int}+\hat H_{irr}$$ \begin{array}{l} \hat H_0=\hbar\omega ...
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24 views

What is the Holo-Exchange symmetry of the tensor $\chi^{(2)}$?

In a paper by Lu-Ming Duan and Guang-Can Guo, they develop an alternative approach to quantising the EM field in a nonlinear and inhomogeneous media. In this derivation, they use the holo-exchange ...
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2answers
46 views

Do the results of this laser experiment demonstrate nonlinear optical phenomenon?

In my photonics class, we conducted an experiment to observe the Beer-Lambert law and the effects of filters(absorption, transmittance, and reflection). We shined a red(632nm) 5mW Helium-Neon laser ...
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53 views

Derivation of Yurke-Stoler state

The evolution of a coherent state $\vert\alpha\rangle$ in a Kerr-nonlinear medium $H=\Omega (a^\dagger a)^2$ is given by $$ \vert \psi(t) \rangle = e^{-\vert\alpha\vert^2/2}\sum_{n=0}^{\infty} \dfrac{\...
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44 views

Pump Probe Spectroscopy Zero Delay

I am setting up a Non Degenerate Pump Probe Experimental Setup, in my lab, as part of my Master's Project. Due to the constraints of the way the lasers have been set up in the lab, I am unable to ...
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1answer
121 views

Coherent state under Kerr evolution

I have a bosonic mode associated to the usual operators $a$, $a^\dagger$. I'm interested in knowing the evolution of a coherent state $\vert \alpha \rangle = e^{\alpha a^\dagger - \alpha^\ast a}\vert ...
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2answers
377 views

Maxwell's equations, nonlinear media, and dynamic response

Maxwell's equations in the vacuum with electric permittivity $\epsilon_0$ and magnetic permeability $\mu_0$ are given as: $$\nabla \cdot \vec E = \frac{\rho}{ \epsilon_0}$$ $$\nabla \cdot \vec B = 0$...
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77 views

Optimal pump wavelength for frequency doubling in periodically poled media

Background I am currently working on achieving second harmonic generation (SHG) in periodically poled lithium niobate (PPLN) using a 1560 nm pump laser. PPLN makes use of quasi-phase-matching of the ...
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1answer
48 views

What is the relationship between the nonlinear susceptibility and the effective nonlinear coefficient?

Oftentimes, I see equations for non-linear optics expressed in terms of the non-linear susceptibility tensor. Other times, however, I see these same equations expressed in terms of an effective non-...
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1answer
52 views

What are the material restrictions for a $\chi^{3}$ non-linear optical material?

For instance, I know that $\chi^{2}$ materials need to lack inversion symmetry, but what about $\chi^{3}$ materials?
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1answer
119 views

Furry's theorem and spontaneous parametric down-conversion

In spontaneous parametric down-conversion, a single photon interacts with a nonlinear medium to produce a pair of lower energy photons. It is observed that energy, momentum, and orbital-angular-...
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1answer
48 views

Non-linear optics - solve differential equations coupled with the finite difference method [closed]

I have these three differential equations in which I need to solve numerically: $$ \frac{dn_0}{dt}= -n_0(t)W_{01}(t) + n_1(t)K_{10} $$ $$ \frac{dn_1}{dt}= -n_1(t)W_{12}(t) - n_1(t)K_{10} + n_2(t)K_{...
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1answer
94 views

Spin conservation in spontaneous parametric down-conversion (SPDC)

If one pump photon "decays" through the process of spontaneous parametric down-conversion into two photons how can the spin be conserved?
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1answer
240 views

How to calculate the dispersion parameter of a Fiber?

I am writing a presentation about DCF Fibers. From many articles i am reading, the dispersion parameter of Fibers are given. But it is not shown how it has been calculated. For example ,in this ...
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113 views

When is the permittivity tensor not Hermitian?

I understand that a permittivity tensor is symmetric if there is no absorption. On the other hand is it always Hermitian? Under what cases would that not be the case?
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37 views

What is the gain control technique used in optics?

In optics, it is said that The gain bandwidth and gain flatness of Amplifiers are enhanced utilizing gain control techniques.What techniques are they referring to ? I know the automatic volume ...
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1answer
141 views

Difference-frequency generation: physical interpretation

Sum-frequency generation is easy for my to understand. Two photons combine their energies in a nonlinear medium and out comes one photon with the sum of both energies. But Difference-frequency ...
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110 views

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 ...
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2answers
152 views

Higher-order dispersion in non-linear optics

In many cases, dispersion of an optical medium is presented by saying that the dependence of the wavenumber $k$ on the (angular) frequency $\omega$ can be expanded in Taylor series as: $$ k(\omega) = ...