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Questions tagged [photonics]

Photonics is the science of creating, moving, and detecting photons

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Does the creation operators for photons with different polarization commute?

Let $\hat{a}^{\dagger}_{\sigma}$ be the creation operator of a photon with the polarization $\sigma $ towards some reference. What are the commutator relations for the creation operators of a photon ...
Epod's user avatar
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Is luminescence from impact of fast neutral atoms/molecules on a suitable substance known?

Cathodoluminescence is emission of photons by electrons impacting on a luminescent material. The Rutherford scattering experiments detected impacting helium nuclei on a phosphor screen. Many other ...
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Photonic classical and quantum computing

How different is the hardware used for classical and quantum photonic computers? Are there any proposals on hybrid platforms? I'm curious why I never heard of both within the same context, except for ...
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How can the inverse of stimulated emission be distinguished from "normal" absorption?

A simple system with two energy states can absorb an incoming photon (of adequate energy) to get excited, and it can relax by either spontaneously emit a photon afterwards or get stimulated by another ...
Tobias Kienzler's user avatar
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Interferometer designed to create diffraction in free space

I designed the following interferometer: If the light beam -theoretically- is very narrow , will light be diffracted away from point B from QED's perspective?
Wael Khatib's user avatar
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Destructive interference pattern perpendicular to photon's propagation direction

I'm studying the interference pattern for light. For example, the following is the interference pattern for double slit experiment: I'm curious to know if there is an existing interference pattern ...
Wael Khatib's user avatar
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What happens if obstacles (walls) been put where destructive interference occurs in double slit experiment?

If photon doesn't have probability to be in dark (destructive interference) area, what will be the effect of adding obstacles (walls) in the dark (destructive interference) area for the double slit ...
Wael Khatib's user avatar
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Inconsistency between Jones vectors and Stokes parameters

Plane wave equation : \begin{equation} \vec{E}(z,t)=\left| \begin{array}{c} E_{0}^{x}e^{i\delta_{x}} \\ E_{0}^{y}e^{i\delta_{y}} \\ 0 \\ \end{array}\right|e^{i(\omega t -kz)}\quad,\quad E_0^{x,y} \in\...
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Is IR Emissivity changed by being submerged in fluids other than air?

I am aware that IR emissivity happens in a vacuum, but treating vacuum as the best case rather than the worst case (where there is nothing adjacent to an emitting atom/surface). Where should I start ...
MustTidyOffice's user avatar
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Collection efficiency of mirror

I want to compare plane and parabolic mirror for collection of photon from a point source. Intuitively, parabolic mirror focuses all rays from point source and gives parallel rays therefore has a ...
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Encoding information on photon qubit

I study QKD which relies on the single photon as a qubit, on which information is encoded. There are many protocols which mainly differ on how information (bit) is encoded on the qubit : polarization ...
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Does the beam image invert on each round-trip through a hemispherical laser cavity?

When one creates a hemispherical laser cavity, using one flat and one concave mirror, does the beam image invert each time it makes a round trip? I know when passing through the focus of a lens/mirror,...
Bo Mungton's user avatar
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Tightly-focusing a single photon

I'm curious about the feasibility, both theoretically and experimentally, of tightly focusing (or spatially trapping) a single photon to guarantee its precise targeting. If it’s possible, isn’t it ...
Omid's user avatar
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The expression of photocurrent

Consider an electro-magnetic field represented in phasor notation $E_0e^{-jwt}$ incident upon a photodetector/photodiode, what is the expression of the generated photo-current $I(t)$? Here $E_0e^{-jwt}...
Goldenalcheese's user avatar
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How to get good visibility in Single-photon_interference?

This question is specific to the experimental quantum optics community. I am attempting to perform a Mach-Zehnder interference experiment using single photons as a source. However, I am encountering ...
Kanad Sengupta's user avatar
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How to rotate the polarization of photons?

What device is used to rotate photons from H to V. Does it change the energy of the photons? I heard about half wave plate?
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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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Mode Interferometers (MMI) versus waveguide couplers

In Photonics Integrated Circuits Mach-Zender (MZ) modulators are very often used. This design splits one wageguide into two spatially separated waveguides and makes them to rejoin, in order to ...
Ang'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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Photon as a qubit

I am studying Quantum Key Distribution which relies on photonic qubits, the photon. Indeed, this one is viewed as a qubit, that is a two state system, just like the spin of an electron, an atom with ...
deb2014's user avatar
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Transmittance of one material through a multilayer

Good morning, I have the transmittance and the reflectance spectrum of PET (Polyethylene terephthalate) and I also have the transmittance and the reflectance spectrum of PET + Copper (50 nm). I would ...
Brising's user avatar
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Why does Near Infrared (NIR) light allow deeper imaging in biological tissue in Multiphoton Microscopy?

I have been reading this paper on multiphoton microscopy (https://www.nature.com/articles/nphoton.an.2010.2) and I am very confused about something. Here is a quote from the paper: "The NIR ...
Sigma123's user avatar
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What is a true delay line and is there possibly a false delay line?

I'm reading "Silicon nitride passive and active photonic integrated circuits: trends and prospects" and one of discussed application of $\rm SiN$ is "true delay line". All the ...
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Missing Scaling Factor of the Electric Field of Hermite-Gaussian Modes

I am currently looking at A. Yariv's book "Introduction to Optical Electronics" 2nd edition. In Chapter 3 "Propagation of Optical Beams in Homogenous and Guiding Media", Yariv ...
Hikikomori's user avatar
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What's the difference between a rhombus lattice and a hexagonal lattice in photonics?

I am learning photonic crystal slabs. I try to figure out what the difference between a rhombus lattice and a hexagonal lattice in photonics is? All I know is that they have diffefent Brillouin zones,...
Terry Leung's user avatar
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Waveguide allowed modes | Transverse resonance condition

Consider a planar waveguide for example. The guiding index is $n_f$, and the cover and substrate indices are $n_c$ and $n_s$ respectively. Let the waveguide propagate along z, and have a height $h$ in ...
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Effective Refractive index of a mode less than that of the cladding refractive index?

Can the effective refractive index be less than the cladding if the waveguide width is very small. For example for the case of a ~100 nm waveguide.
user35115's user avatar
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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
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Optical Properties of Heavily Doped Silicon in the Visible and Near Infrared

I am looking for a model of the changes in the complex refractive index of doped Silicon based on the doping level and type in the visible and near-infrared wavelengths (400-1000 nm). I have seen ...
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What photonic properties of a subwavelength plasmonic cavity make it generate saturated structural colour in just one layer?

I have a photonics question regarding a paper I am reading. Physics is not my area of study so please be kind :)) https://doi.org/10.1126/sciadv.adf7207 In this paper, the group has fabricated a self-...
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How accurate is coincidence counting, and how do we know?

Experiments that feature the creation of entangled photons through SPDC often make use of coincidence counters. How can one photon be accurately correlated with its entangled partner by a coincidence ...
OneStrangeQuark's user avatar
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1D Photonic Crystal Photonic Bandgap Example Confusion

I am reading through Optoelectronics & Photonic Principles by Safa O. Kasap and am not understanding section 1.17 on Photonic Crystals. Here is an excerpt: The book mentions how some waves suffer ...
fordanjen's user avatar
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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_{...
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How are frequency combs obeying the energy conservation?

The operational principle of frequency combs is that you generate very short pulses (in time domain), and that in the frequency domain (due to Fourier's transform) the spectrum of such pulses is a ...
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Is photonic computing subject to the Landauer limit?

In what way are they both related in terms of computation? Are photons subject to thermodynamic limits?
Akshay's user avatar
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What is the state of the art in nanophotonic biosensing?

Over a decade ago I've been doing research in nanophotonic biosensing and all the reviews from those times were very impressive. Some plasmonic structures were capable of single-molecule detection and ...
user46147's user avatar
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4 votes
2 answers
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Are two localized single-photon states always invariant under the particle exchange?

In a text book for quantum communication, I learned that one generates optical pulses (wavepackets), each of which contains only one photon. For instance, the state of two wavepackets are described by ...
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Optical software - thin film interference

I am currently using a software called "SCOUT" to thin film interference simulation, and I would like to know if there is a better software to do this type of simulations. My goal is to vary ...
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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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Far-field analytical solution

I want to compare FDTD far-field solution for reflective diffraction with analytical solution. It seems more complicated than transmission diffraction. Please suggest resources or codes for reference.
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1 answer
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How hard is it to obtain perfect alignment of optical equipment?

While reading a published paper, I read that some photons were being detected at the arm of a Michelson interferometer which was intended and set to have approximately perfect deconstructive ...
OneStrangeQuark's user avatar
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1 answer
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dB of squeezed light is equivalent to how much squeezing in different directions?

In many structures, the amount of squeezed light is expressed in dB. I wanted to know what is meant by squeezed light in dB. For example, 10 dB of squeezed light is equivalent to how much squeezing in ...
Saber's user avatar
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How to check laser beam polarization

Just like in my question. How to check laser beam polarization? What's the easiest experiment to do that will help me understend what type of polarization is present in my laser beam?
Kacper Kinastowski's user avatar
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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 ...
Saber'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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1 answer
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Does the substage condenser numerical aperture cap total resolution of an imaging system?

Amongst formulas to estimate the theoretical resolution of a transmitted light microscope, I often see: $$ \delta = \frac{1.22\lambda}{NA_{obj} + NA_{cond}} $$ Where $NA_{cond}$ is the numerical ...
ilykos's user avatar
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1 answer
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Can neutral density filters be substituted by other parameters of the imaging system in any context?

One of illuminators in my imaging system has a built-in neutral density filter. I am considering removing it and changing the exposure time of the imaging system's camera to compensate for the ...
ilykos's user avatar
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Mathematically, how exactly is $\langle \vert(E_m + E_r) \vert^2 \rangle$ calculated?

In a section on interferometry, my photonics textbook says the following: Now, let's consider the signal obtained at the output of the interferometer. In general, the fields returned on the ...
The Pointer's user avatar
1 vote
1 answer
124 views

How to measure spectral irradiance vs wavelength for sunlight?

I am currently working on a project where I need to measure the spectral irradiance over a submerged solar panel at different depths of water. But I do not really know what can be used to measure it. ...
Kalpajit Roy's user avatar
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Simulation photosystem light absorption in Quantum computing

Basically, I want to simulate the above photosystem process of light absorption. Above is a diagram of laser beams shot into antenna pigment molecules and traveling to the reaction center. Two ...
Levent Ozbek's user avatar

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