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Questions tagged [non-linear-optics]

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Polarization in nonlinear optics

I've very recently started learning nonlinear optics by reading the well-known textbook by Robert W. Boyd (3rd ed.). I don't find the book an excellent choice for self-study. The fundamental concepts ...
apadana's user avatar
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How to choose the right cavity for non-linear process (SHG/SPDC)

I'm currently reviewing Spontaneous-Parametric-Down-Conversion (SPDC) and Second-Harmonic-Generation (SHG) inside optical cavity. I have found some information on them such as the different type (...
Chris Ze Third's user avatar
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Interpretation of Schmidt coefficients and JSA figure

I'm currently using a python code provided by a fellow PhD student in order to obtain the grating value of a periodically poled crystal (for SPDC process). I must precise this program is under DMCA so ...
Chris Ze Third's user avatar
1 vote
1 answer
22 views

Round-trip equations of fields in a cavity with nonlinear medium (SPDC)

I'm having a lot of trouble trying to understand a set of equations corresponding to the dynamic of field operators of the signal and idler beam in a cavity where one places a non-linear crystal. The ...
Chris Ze Third's user avatar
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Nonlinear optics begins with a presentation on the polarization expansion, for both insulators and metals. how to reconcile this for metals?

Typically a first presentation of nonlinear optics discusses a taylor expanded form of polarizability. That makes sense (to me) in insulators, where there are bound electrons that are polarized. But, ...
Spinor's user avatar
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1 answer
83 views

The relativity of simultaneity in two-photon absorption

In the two-photon absorption (TPA) process, when there is no intermediate state, it's required that two photons are absorbed either simultaneously or semi-simultaneously, with a relatively short time ...
Omid's user avatar
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32 views

Why self-phase modulation can prevent mode-locking?

Several sources claim that Self-Phase Modulation (SPM) can prevent mode locking (ML) in fiber lasers (e.g. rp-photonics). I have experience of a silica fiber laser based on active ML where steady ...
Ang's user avatar
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28 views

Optical properties of non-Newtonian fluids

I'm interested in understanding the distinctions between non-Newtonian fluids and regular Newtonian fluids regarding their optical properties, including refractive index, nonlinear optical behavior (...
Omid's user avatar
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2 answers
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Does rotation the polarization of one twin photon rotate the other?

After a nonlinear crystal there are two photons in HH+VV state. What happens to the state if one of the photons in the pair is rotated? Does the state stay the same or it flips to HV+VH?
Mercury's user avatar
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2 answers
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The relative phase of photons in two-photon absorption

In two-photon absorption (TPA), the relative polarization of the two photons about to be absorbed simultaneously by an atom is crucial in determining the TPA rate. However, there is a lack of ...
Omid's user avatar
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How to calculate vector potential $A$ from electric field $E$ in the field of strong field approximation? [closed]

In order to simulate higher harmonic generation (HHG) using the strong field approximation (SFA), we need to calculate vector potential $\textbf{A}$ from the electric field $\textbf{E}=E_{0}f(t)\cos(i\...
Dennis Luo's user avatar
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Mach Zehnder Do-it-yourself

I have a red laser and BS. Can I make MZI at the lab? I heard that is very difficult to achieve the calibration. What is expected to be seen after BS2? A dark spot at centre with fringes around? I ...
Mercury's user avatar
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3 votes
4 answers
255 views

Can there be two different physical units (or dimensions) for a same physical quantity?

I was going through this book "Nonlinear optics" by Robert W. Boyd for my postgraduate subject in Nonlinear optics and I came across the different orders of nonlinear susceptibilities. From ...
soulfourier's user avatar
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1 answer
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Why my optical limiting behavior is Descending? (on input intensity- output intensitydiagram)

I measure some nonlinear optical materials and I know that output intensity respect to input intensity should be ascending like this diagram. but for me, for one of my materials, this diagram is ...
moj.enjoy's user avatar
2 votes
1 answer
66 views

The idea behind Sagnac loop for entangled pair generation

I have a question which I cannot intuitively understand. In many articles I saw a Sagnac loop being used to generate polarization entangled pairs of photons. The principle is rather simple - you split ...
Gustas's user avatar
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Will a laser with low power - operating as continuous wave - generate supercontinuum in nonlinear materials?

Some nonlinear optical materials, such as for example glass doped with As2Se3 or As2S3, are able to generate supercontinuum if a single mode laser pulse, in range of a few watts, is launched into the ...
Jimski's user avatar
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Are there any nonlinear crystals or other transparent materials that can produce anti-Stokes, phase matched, frequency shift of laser light?

While some nonlinear crystals can convert incoming laser light into harmonics, thus for example doubling the light frequency, are there any crystals or other transparent materials that can reduce the ...
Jimski's user avatar
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Two-qutrit preparation using linear optics

How can I prepare a two-qutrit product state (let's say $\frac{1}{\sqrt{2}}|0\rangle|0+2\rangle$ using optics? Do I need a BBO crystal (as I know BBO crystal produces an entangled state), or can I use ...
Pratapaditya Bej's user avatar
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How would I account for non-linear refractive index effects in a nitrogen based medium?

I am trying to estimate the clamped intensity of a 90 fs femtosecond laser when it passes through a flow of nitrogen that is exiting a nozzle. Prior to the nozzle, the incoming nitrogen flow is heated ...
Nikkhil Chander's user avatar
1 vote
0 answers
37 views

Can all classical optical materials be described by perturbation theory?

In quantum field theory (e.g. lattice QED), perturbation theory can "break down" when interactions become too strong. Can something like that happen in classical non-linear optics? Can there ...
Adomas Baliuka's user avatar
1 vote
2 answers
164 views

Understanding the use of Group Velocity Dispersion Optics

I am a bit confused on the topic of GVD. Most information I read on the topic tells me something like this: "GVD means that the group velocity will be different for different wavelengths in the ...
fordanjen's user avatar
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What is meant by entanglement in spatial degrees of freedom and how is it different from correlation in spatial degrees of freedom? [duplicate]

I am studying about SPDC (spontaneous parametric down conversion) and I come across phrases like "perfect correlation in spatial degrees of freedom" but never "entanglement in spatial ...
QuantumOscillator's user avatar
1 vote
0 answers
67 views

Non-Linear Crystals (BBO) splitting photons

So from what I've studied till now about Photon Entanglement is that when we input a photon of a particular wavelength ($\lambda$) into a BBO crystal (a non linear $\chi^2$ crystal), it has a ...
Harshdeep Chhabra's user avatar
3 votes
0 answers
54 views

Quantization of electrodynamics in a nonlinear dielectric medium

Recently I read this paper https://doi.org/10.1103/PhysRevA.30.1860 by Hillery and Mlodinow about the (canonical) quantization of electrodynamics in nonlinear dielectric media. They assume that the ...
WillHallas's user avatar
1 vote
2 answers
117 views

Second Harmonic Generation in metals

Assuming a metal driven by a femtosecond laser pulse could generate second harmonics, are these harmonics radiative? In other words, do they reach the far-field?
Ali Kefayati's user avatar
2 votes
2 answers
86 views

Mapping between quadrature squeezing and photon-number squeezing

It is possible to get quadrature squeezed light where on one quadrature the uncertainty is less than the of a coherent state while in the other one, orthogonal to it, it is larger. Is it possible, by ...
Goose's user avatar
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2 answers
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What is Helicity in High Harmonic Generation?

The harmonic spectra are calculated as $|FT(\frac{d}{dt}\mathcal{J}(t))|^2$, where $FT$ si the Fourier Transform and $\mathcal{J}(t)$ is the current. We need to identify which multiple of incident ...
Debamalya Dutta's user avatar
2 votes
0 answers
36 views

Relation between polarization and susceptibility for nonlinear processes

I've been confused about this for a while-- Boyd mentions that the second order polarization is related to second order optical susceptibility as $P_i(\omega_m + \omega_n) = \epsilon_0\sum_{(mn)}\chi_{...
phy boi's user avatar
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SLM pulse shaping to delay (and advance) ultrashort pulses in time

I am trying to replicate some of the experiments discussed in this excellent publication: SLM for pulse shaping In particular, I replicated the setup configuration in Figure 14 and I want to use the ...
France's user avatar
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2 votes
1 answer
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"Thermal blooming" - where does the term come from?

An important nonlinear effect during propagation of high-power lasers through air (and other material media, I think) is thermal blooming, where heating due to absorption of laser light changes the ...
apadana's user avatar
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1 answer
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How to find nonlinear conductance?

For quantum transport at the level of linear response, there is the Landauer-Buttiker formula. And for tight-binding models, there are programs targeting such calculations, such as the kwant package. ...
xiaohuamao's user avatar
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Ambiguity in picking up second harmonic generation

I want to derive some formula for second harmonic generation (SHG) susceptibility $\chi(2\omega;\omega,\omega)$. To this end, I use Matsubara Green functions to find the second-order response $$J^a_q=\...
xiaohuamao's user avatar
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270 views

Second-order optical conductivity in Green's function form

In linear response, Kubo formula can be given in terms of eigenstates and the Hamiltonian as $$\sigma_{\mu\nu}(\omega)=\frac{i\hbar}{V}\sum_{mn} \frac{f_n-f_m}{\varepsilon_m-\varepsilon_n} \frac{\...
xiaohuamao's user avatar
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1 vote
1 answer
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Feynman Diagrams for Spontaneous Parametric Down Conversion

Nonlinear optical process called the 'Spontaneous Parametric Down Conversion' (SPDC) divides a photon of high frequency into two photons of lower frequencies with energy conservation. But I see no ...
류민석's user avatar
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51 views

Does self-phase modulation (SPM) depend on Raman scattering?

SPM and Raman scattering both cause spectral (frequency domain) broadening of ultrashort laser pulses. So I was wondering if what we know as SPM spectral broadening is dependent on Raman scattering at ...
apadana's user avatar
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Formation of optical solitons in microresonators

Optical soliton formation in laser systems with devices that facilitate mode-locking such as a saturable absorber help me understand why solitons form in the first place. However, when one considers a ...
Paddy's user avatar
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1 answer
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How can one model squeezed states in 3D optical modelling software?

I would like to model squeezed light and its evolution (such as when passing through lenses after being generated) using optics software such as OptiFDTD or ZEMAX. However, I don’t see any way to make ...
Sciencemaster's user avatar
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103 views

Why do the signals for second harmonic generation and third harmonic generation differ in the strong focusing limit (strongly focused gaussian beam)?

In Ward & New (1969), the expression for second harmonic generation (SHG) and third harmonic generation (THG) intensity is derived for the focal volume of a strongly focused gaussian beam (axially ...
A mindful mundu's user avatar
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75 views

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 ...
Saber's user avatar
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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 ...
Shogo Makashima's user avatar
3 votes
2 answers
176 views

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 ...
Samuel's user avatar
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1 answer
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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 ...
Rima's user avatar
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2 answers
143 views

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?
SHD's user avatar
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-1 votes
1 answer
76 views

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 ...
Merugu Arun Kumar's user avatar
0 votes
1 answer
41 views

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 ...
Andeloth's user avatar
2 votes
0 answers
127 views

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 ...
김상배's user avatar
1 vote
1 answer
99 views

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 ...
GayanW's user avatar
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2 votes
2 answers
195 views

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 ...
blocks's user avatar
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2 votes
1 answer
436 views

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 ...
gang liu's user avatar
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1 answer
65 views

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 ?
avi0105's user avatar
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