Questions tagged [non-linear-optics]
The non-linear-optics tag has no usage guidance.
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How to creat a squeezed-state light in integrated-photonic devices
I am interested in studying (squeezed-state light in integrated-photonic devices by means of four-wave mixing). I would like to be completely familiar with the working method and all the devices that ...
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Second-order polarization equations
I'm reading through a tutorial about the basics of nonlinear spectroscopy, and I recently came across an equation describing the density matrix of a system that has been acted upon by a pair of laser ...
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How do I calculate the numerical aperture and refractive index of the waveguide?
I have a step-index optical fiber with a core and a cladding. I need to calcuate the numerical aperture and refractive index of the core (assuming the laser beam is gaussian). So the numerical ...
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How is phase matching equivalent to momentum conservation?
I am studying about phase matching and how it is being used to maximise the output power in various experiments. But I am not able to understand how can phase matching be equivalent to momentum ...
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Microscopic origin of phase matching in second harmonic generation
In second harmonic generation (SHG), the second-order nonlinearity of a medium is used to double the frequency of a driving field. In Boyd's book "Nonlinear Optics", he derives the solution ...
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Effects of nonlinearity and dispersion on a pulse
I have some basic doubts on Nonlinear and dispersion effects on a pulse.
How does a pulse shape change in temporal domain when passed through:
nonlinear medium with strong $X^2$ effect
nonlinear and ...
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Why do non-linear optical effects occur?
Why do non-linear optical effects occur? Why do the materials respond differently at high intensities and at some resonant frequencies?
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Will photons still be entangled in polarisation, when I know its polarisation? [closed]
Imagine if i have a KDP crystal (the property of the KDP crystal is, the polarisation of singnal and idler photons that come out by parametric down conversion is orthogonal to pump photon, and both ...
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What causes phase walk-off reversal in inverted domains in Quasi-Phase-Matching?
Lets take for example a Periodically Poled Lithium Niobate crystal (PPLN) used in a nonlinear process such as Second Harmonic Generation (SHG). For this crystal, the purpose of periodic poling is to ...
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What is difference between Electromagnetically induced transparency (EIT) and Coherent population trapping (CPT)?
EIT: Electromagnetically induced transparency
CPT: Coherent population trapping
When two resonant light fields (probe field and strong coupling field) are incident on an opaque material whose atoms ...
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PMT Transit time spread (TTS) for an ultrafast laser used for surface second harmonic generation?
I'm in the process of building a setup for Single photon counting in 300 - 400 nm.
Basically I'm trying to detect SHG (Second harmonic generation) reflected off of a surface. (SHG is a non-linear ...
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Can modulation of continuous light by an optical chopper generate new frequency photon?
This picture is from thorlabs' website.
Continues light can be modulated by an optical chopper. According to the fourier transform theroy, I think this kind of modulation will bring new frequency ...
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Where can one find the expression for the origin of the Hamiltonian of the Kerr nonlinear interaction in an optical cavity?
Recently, I was reading some papers about Kerr media in a cavity, and I found that almost all articles give the Hamiltonian as
$$H=K\hat{a}^\dagger\hat{a}\hat{a}^\dagger\hat{a}.$$
In order to ...
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Can SHG be used to determine whether a single crystalline sample is centrosymmetric or non-centrosymmetric if the sample is metallic and magnetic?
Non-centrosymmetric crystals can give rise to second harmonic generation (SHG) whereas centrosymmetrics cannot. This property of crystals can be used to determine the presence or absence of centre of ...
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Sum frequency generation and optical rectification
What is the difference between sum frequency generation and optical rectification if frequency mixing is at the core of both the processes. Is one of these processes a subtype of order ?
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Why does non-linearity come into picture only at a large intensity of optical fields?
I have read that for sufficiently large intensities of optical fields (of the order of $10^8$), we can actually observe a non-linear relationship between the polarization and the field, given as
$$\...
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Mechanism: Instantaneously vary frequency of photons emitted, or passing, by, over a wide range of frequencies, with reliable consistent precision?
For an optical computing application, I need to set frequency of photons emitted or passing by a small mechanism, instantaneously, and it needs to be able to change this frequency from one instance to ...
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Why does $Δn$ saturate in a Kerr medium after an intensity threshold?
I am running an FDTD code to study the nonlinear refractive index change in a very thin Kerr medium for certain intensity values. I have noticed that after reaching an intensity threshold $Δn$ ...
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What is the difference between normal surfaces and index ellipsoid in crystal optics?
What is the difference between normal surfaces and index ellipsoid in crystal optics? Why does the normal surfaces have two shells but the index ellipsoid have only one? And how to analyze light ...
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Difference-frequency-generated (DFG) spectral width
If we have two laser beams with central wavelengths $\lambda_1$ and $\lambda_2$, (one with a spectral width of $\Delta\lambda_2$ and one with negligible spectral width), interacting in a non-linear ...
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Photon-wise justification of chosen compensation crystal length in SPDC
I know a compensation crystal in SPDC schemas serves the temporal walk-off erasment purpose. However, I am not sure why half the length of the original crystal is opted for. I read an article that ...
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How can we generalize the definition a non-linear media?
According to the definition: Nonlinear media are dielectric materials whose polarization density changes nonlinearly if a strong field is applied to them. If the field is small the nonlinear terms ...
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Why are pulsed lasers are the main tool used in nonlinear optics applications, instead of CW sources?
Why we often use pulsed lasers for nonlinear optics applications (such as SHG) instead of continuous wave lasers?
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Can second harmonic generation be stronger than fundamental frequency interaction in metals/dielectric nanoparticles?
Quick question regarding non-linear optics:
A nanoparticle, either dielectric or metallic present second harmonic generation. The dielectric, following the simplest modelization as:
$$E(2\omega)\...
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Complex electric field in second order polarization
I am reading an introductory article on nonlinear optics. Here is what the part that's troubling me says:
$$\tilde E(t) = Ee^{-i\omega t} + \text{c.c} $$
When this electric field is incident on a ...
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Four-wave mixing and modulation transfer spectroscopy: why do sidebands appear on the probe?
I'm trying to understand modulation transfer spectroscopy in simple terms.
For those unfamiliar with it, this article gives a very good summary. To sum it up, two counterpropagating beams, a pump and ...
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Second harmonic generation (SHG) in centrosymmetry material
I know SHG in centrosymmetry material is not possible as "$E(t)\rightarrow -E(t)$" and "$P(t) \rightarrow -P(t)$" one should get the same $P(t)$. I am confused why $E(t)$ and $P(t)$...
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What do the subindices $jkl...$ represent in the nonlinear polarization equation?
After studying this article on non-linear polarization, I have two main questions:
The first was which is the origin of $n$th order susceptibilities; this was mainly already answered by a previous ...
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QED vacuum as a classical dielectric medium?
I have heard this analogy a few times, particularly in the context of vacuum polarization. To what extent can the QED vacuum be modeled as a classical dielectric medium? Can one compute effective ...
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Physical origin of Kerr effect
I was wondering if someone could explain to me the physical (not mathematical) origin behind the Kerr effect and why it results in birefringence in materials.
Also, can the birefringence be introduced ...
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Why do we get rings in the Spontaneous Parametric Down conversion (SPDC) process?
In the SPDC process, the phase-matching conditions between the o-rays and/or e-rays have to hold for the down-conversion process to take place. Say we have a non-collinear phase-matching at the plane ...
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Requirements for Z-scan or I-scan measurements of nonlinear optical materials
I am looking to understand what requirements there are for any version of Z-Scan technique or the I-scan technique. These techniques are used for measuring nonlinear absorption and nonlinear ...
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What are the factors that decide which type of SPDC (Type I or II) occurs in a Non-Linear Crystal?
I have been reading through some literature on the theory of Spontaneous Parametric Down conversion (SPDC), their types, the phase-matching condition, etc. To my understanding, the downconverted ...
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Can we predict harmonic generation from Maxwell's equations?
One typical experimental setup to generate harmonics from a laser pulse is to irradiate some plasma stab with a laser, register both reflected and transmitted waves, and the spectrum of those waves ...
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Squeezed quantum states of light
I am a beginner in quantum optics and started from reading the Fox's book. I got to Ch.7, where there is a discussion about the amplitude-squeezed states. I am really puzzled by the effect of phase ...
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Entangled Photon Sources: how to choose the pump wavelength in SPDC?
I found several papers dealing with entangled pairs of photons generated by means of a setup consisting in a pump laser and a nonlinear crystal, such as BBO or KTP and here the incoming photons ...
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Restoring force of electron-nucleus spring model (Lorentz oscillator model)
The restoring force should fulfill at least two criterion
Experience repulsive force when it is compressed and attractive force when it is extended
The restoring force always increases with distance ...
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One-half factor representing power or energy
In a book on optical solitons, the following is said-
When loss or gain is taken into account, the equation -
$-i\frac{\partial u}{\partial z} = \frac{1}{2}\frac{\partial^2u}{\partial t^2} + |u|^2u$ ...
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Where can I find some typical nonlinear optical materials SHG working region?
Some example materials are KDP, LiNbO$_3$ and BaTiO$_3$. Where to find their SHG working region? Like some of them perfroming their SHG best in red light region.
I've looked dozens of papers but ...
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Nonlinear Optics: SHG and OPO
I am new to nonlinear optics, and recently I started studying about the second harmonic generation (SHG) and the optical parametric oscillation (OPO) where these two nonlinear interactions are ...
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Why can't gases produce second harmonic generation (ie, why is $\chi^{(2)}$ always zero)?
To quote wikipedia on second-harmonic generation:
Since media with inversion symmetry are forbidden from generating
second-harmonic light via the leading-order electric dipole
contribution (unlike ...
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Inversion symmetry for Second Harmonic Generation
I read this question "Lack of inversion symmetry" in crystal?, but it is not quite clear to me how to clearly define the symmetry. Let me explain with a simple example. In the image below ...
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Can waste heat in specific environments be collected into photons and converted to electricity? [closed]
Crossposted on Engineering SE
Here and here show possibility to combine photons of lower energy to one higher. Thinking of an application, it could be used to dissipate heat from laptop. Liquid ...
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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 ...
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Quantum Dot Surface Area to Volume Relationship
Do the properties off quantum dots depend more on their surface area rather than the volume they occupy?
Depending on the case, then would quantum dots of different shapes show different properties?
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ugly beam profile in noncollinear optical parametric amplifier
I am currently (re)building a noncollinear optical parametric amplifier (NOPA). Such NOPA is seeded with supercontinuum white light (SWL), generated in a sapphire window, by ~100 fs, 795 nm centred ...
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Do laser filaments propagate in a straight line over long distances?
In so-called filament propagation, a powerful laser beam can propagate through a medium without diffraction. This occurs because the beam focuses itself through non-linear optical effects. Self-...
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Multiple Cones in SPDC output
I have seen a picture very similar to this one where it shows the different ouputs for photons during an SPDC process, but the only part (c) makes sense in this diagram. The photon pairs exiting ...
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Is there a nonlinear optical material that absorbs visible light stronger with increasing intensity independent of its wavelength?
One of the main shortcomings of digital image sensors is the quite "unnatural" behaviour for rendering highlights compared to film (and the human eye, I guess). Typically, with increasing ...
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Is there a frequency converting amplifier? [closed]
Frequency conversion means output of the amplifier is at a frequency different from that of the input.
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