# 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 ...
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1 vote
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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 (...
1 vote
18 views

### 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 ...
1 vote
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### 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 ...
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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, ...
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1 vote
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### 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 ...
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1 vote
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### 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 ...
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### 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 (...
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1 vote
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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?
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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 ...
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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 ...
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 ...
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 ...
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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 ...
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 ...
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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 ...
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 ...
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 ...
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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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