Questions tagged [fiber-optics]

Fiber optics is the study of optical fibers, which are thin pieces of high quality optical materials which are able to act as a waveguide for some frequencies of light. This waveguide or 'light pipe' feature of optical fibers allows them to transmit light with very low loss from one end of the fiber to the other.

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Attenuation in microwave and optical communications

I have read that the attenuations of microwave transmission lines and optical fibers are ~1 db/m and ~ 0.2 db/km, respectively. I understand that these values depend on the geometry, design, and ...
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Can a photon in a optic fiber interfere with itself destructively?

In Young double slit experiment the photons interfere with themselves destructively and constructively. So when there is an optic fiber with a mirror end the photon should return back and one can ...
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How do you combine two spatial modes of light into one spatial mode in optics?

Is there a lossless way to combine light coming from two different single photon sources into one spatial mode? Either free space of fiber would be fine. Let's assume the wavelength and polarization ...
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Can a lens based on grating couplers with an optical tap be made in standard silicon photonics (>120nm sizes)?

Given standard silicon photonic feature limits (say no finer than 120nm), am I right in thinking that it's not very feasible to create a low loss vertical grating based lens that also can tap a ...
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Mention what type of optical fiber is most efficient for signal propagation and why?

I have been researching on this question since a week I am unable to get the correct answer weather it is Graded index-Multimode fibres or Step index-Multimode fibres or other?
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Is quantum network security an application of quantum entanglement?

If true, does it assume the link between the sending and receiving sides or servers acting on their behalf to be fully optical fiber physical layer or what practical approach is that heading towards?
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How is metadata transmitted alongside data, through light pulses (e.g. fibre optic)?

So fiber optic is used top transfer information around the world, including this post, between my computer and the SE server, wherever that is. But as I read, that info is transmitted through light ...
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Copper or Glass for Low Latency?

I'd like to preface the main content of this post with the following: I understand this question may be equally suited to the Network Engineering Stack Exchange, but I believe the answer relies on a ...
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Etendue of the eye

I am tasked with calculating the Etendue of an eye with the given values: diameter of the pupil = 4 mm diameter of the retina (the active area) = 6 mm distance from the lens to the retina (b) = 20 ...
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Stark level manifold

In this figure from https://www.rp-photonics.com/effective_transition_cross_sections.html: When a high energy photon (920nm) is absorbed followed by phonon emission to lower energy level in the ...
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Evanescent and Gradient force on optical waveguide

Let's say that on the surface of the cladding we have evanescent field due to the total internal reflection between the core and the cladding. The refractive indices of the the core is 1.45 and the ...
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Easiest way to achieve low divergence beam coming out fiber

So I have a green (I plan to swap it with 940nm IR) LED shining the other end of an optical fiber and I want to produce a 5mm spot at 5cm. The conventional way to achieve this would be with a lens but ...
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Ovalization of a pvc pipe under a weight

I'm not sure if this is the right place to ask this question, but it came up in one of my physics courses so here goes. I want to measure a weight using a Fiber Bragg Grating optic cable. Someone ...
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Why trivalent atoms of rare earth elements are used as gain medium for laser

In rare earth element based gain medium for laser such as ytterbium,erbium,thulium.The gain medium is a trivalent atom ie Yb3+,Er3+ why cant be Yb2+/Yb1+ or Er2+/Er2+.
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Min spot size for light collimated from an optical fiber?

We are currently setting up an experiment in which we need to pipe laser light from one optical table to another. One way we were thinking of doing this was by coupling into an optical fiber, running ...
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How to make laser written waveguides?

I don't know if this is the right place to make such a question, but I have spent a few days trying to get a review or really informative article on how to make Photonic Integrated Circuits by laser ...
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Silicon Nitride Waveguide

Does the Silicon Nitride Waveguide (Si3N4) has a cladding ?! I read an article that they use the evanescent field of silicon-nitride waveguide.. If the answer yes it doesn't has a cladding then can I ...
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Collection efficiency of a confocal microscope vs. numeric aperture

Setup I am trying to estimate the collection efficiency of a fiber-based confocal microscope depending on the numerical aperture (NA) and diameter of the gaussian beam used for illumination and ...
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Mode Field Diameter and Penetration depth of Evanescent field

Source: fobasics.blogspot.com Source: scirp.org As it is shown in the first pic above that the mode field diameter is defined as the mode field decreases to 1/e (in intensity 1/e^2), if I take the ...
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New concept - fiber optic gyro

Dear people of laser science, my understanding of fiber optic gyro is: a single laser beam runs into a cube splitter, then the 2 beams are driven into the opposing ends of a fiber (coil). Then in the ...
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Gradient Force of optical near field

Source: Principles of Nano-Optics, for Lukas Novotny and Bert Hecht. The equations above represent the electric field in the second medium when a light hit a surface and the condition of TIR (total ...
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Contribution of optical 1D and 2D modes in communication

For enhancing optical communication capacity, multimode is one of the trending topic. Many researchers making various devices compatible with more than one mode and claiming that that's a contribution ...
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What is the mechanism behind of optical mode combination in waveguide?

In mode combiner (in waveguide) modes of different phases or the same phase get combined and turn into a new mode. Here is a picture of mode combination process of a mode generator from a paper. ...
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Practical realization of a optical system for a laser

I'm doing a pre-diploma thesis on how to build a laser system for the treatment of carbon nanotubes at my university. I'm relatively far into the whole project, we've already acquired a laser system (...
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Plot the eigenvalue equation for optical fibers LP modes

The eigenvalue equation for LP modes in Optical Fibers is: $$\frac{J_{\ell - 1}(u)}{J_{\ell}(u)} = -\frac{w}{u} \frac{K_{\ell - 1}(w)}{K_{\ell}(w)}$$ where: $J_{\ell}(u)$ is the Bessel function of ...
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Loss of optical fibers — where is the limit?

I'm wondering what is the physical limit of loss in optical fibers. How much of the loss, that can be seen in today's optical fibers can be removed by optimizing the production procedure and how much ...
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Gaussian Beam propogation in a fiber

If we suppose that a Gaussian beam traveles in the fiber with diagonal end as it shown in the image, so I have several questions: 1- Do we get in the end of the fiber Evanescent field (Total ...
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Limits of polarization-maintaining fiber

PM fiber maintains polarization pretty well if the input polarization is horizontal or vertical. But what happens if the input polarization is in a superposition of H and V? For example, $ \frac{1}{\...
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How Gaussain beam exaclty be after diffraction between two mediums?

How it will be the refraction of the Gaussian beam, does one of its sides will go in distortion, and which equations can predict this distortion? Sure I have to use Snell's law to know the angle but ...
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Most general case for Optical Fibers eigenvalue equation

In the system of equations leading to the eigenvalue equation for Optical Fibers, books always avoid the $\phi$ dependence, as mentioned in this previous question. This, however, implies some ...
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How the field profile is in a diagonal end of the optical fiber?

I would like to know how is the propogation of the beam, let's say Gaussian beam profile, in the end of the fiber? Does it go in shift to the lower side? Does it change its shape? And how the near ...
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Beam splitters: fiber vs. free space

In quantum optics, are fiber beam splitters described by the same operators as free space beam splitters? For example, a free-space non-polarizing beam splitter introduces a phase shift for the ...
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Kerr frequency combs in ring resonators

Is it possible to generate Kerr frequency combs using a macroscopic fiber ring resonator? Or is the phenomenon exclusive to monolithic microresonators? If this is possible, would the presence of ...
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Fiber ring resonators versus microresonators

Fiber ring resonators made of multimode fiber are capable of supporting multiple spatial modes. Even fiber ring resonators made of single mode fiber can, under favorable conditions, support a few ...
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Optical fibers eigenvalue equation considering $\phi$ dependency

Consider the system of equations formulated in a previous question (optical fibers continuity of tangent field components across the core-cladding interface): $$ \left\{ \begin{array}{c} e_z^{(1)}(r,\...
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What is the simplest way to get the light of 50 visible LEDs into a multimode glass fiber?

LEDs are cheap. How can I get all their light into a fiber? Even if it is only 1% from each LED, it would be useful. Any proposal is welcome. I read about fiber combiners, but they are not helpful. I ...
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Beamsplitter complex notation

I am trying to understand the formalism presented in this paper about the transmission of a fiber ring resonator. By modelling the coupler as a beamsplitter, the authors write: $$E_{2}=rE_{1}+itE_{3}$...
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Can I (in principle) make an analog fibrescope/borescope for consumer phones using only a fibre optic cable? [closed]

This question is testing my (limited) understanding of optics. Here is the background. Many endoscopes work by using a fiber optic light guide to transmit light to a camera which sits at the end of ...
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Spatial light modulator to generate LG beams

I am learning to use spatial light modulator. My problem is multiple rings coming out when I put the 1st mask (generating optical vortex) on SLM. It should be LG(0,-1) with only one ring. I did not ...
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Collimating a UV LED

I have a task of narrowing a UV LED (375 to 400nm) of diameter 5mm to 1mm on the surface of an object. The LED has a peak output power of 2.2mw (quite low). It has an half Intensity angle of 10 ...
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Brillouin scattering in multimode fibers

Fiber ring resonators made up of single mode fibers often incorporate an optical isolator to suppress the build-up of Brillouin scattering. However, ring resonators made of multimode fibers generally ...
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Optical fibers field analysis, $\phi$ dependence not considered

In optical fibers, the core (with $\varepsilon = \varepsilon_1$) is usually represented by a cylinder of radius $a$, whose axis coincides with the $z$-axis in cylindrical coordinates. The cladding is ...
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Refractive index and optical fibre question

This is an A level AQA question: A signal is to be transmitted along an optical fibre of length 1200m. The signal consists of square pulses of white light and this is to be transmitted along the ...
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How does a fibre's gain influence the performance of an etalon in wavelength selection?

I performed an experiment using a YDF laser and aimed to tune it. A prism was used to refract the output light from the laser and a mirror was used to reflect back a specific wavelength. It lased, ...
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How to decrease the Q-factor of a resonator?

I was trying to create a mode-locked laser in order to create high-intensity light pulses, this experiment was done a while ago and with someone else, and in our notes says that the laser cavity's q-...
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Radial field dependence in optical fibers cladding

Consider an optical fiber whose axis is the $z$-axis. Assume that the electric field $e_z$ along this direction can be written (in cylindrical coordinates) as $$e_z(r,\phi) = A(\phi)B(r)$$ $k_c$ is ...
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Comparision of using two dimensional mode or one dimensional in case of optical data transmission

Many works have been done to increase capacity of optical communication. I saw that some researcher using 1-D mode ,some 2-D to implement their device.The reson of using 1-d/2-d beacuse of their types ...
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What is the relationship of optical mode and data?

This question is on the plot of mode division multiplexing system where it is said capacity crunch can be solved using mdm technique. Now, we know single mode fiber can transmit upto 1Tbps. Now if i ...
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Can I couple 1064 nm and its harmonic 532 nm in a single polarization maintaining fiber?

I have an experiment where I need to get a largish (40 mW) amount of 532 nm light and small amount (<50 µW) of 1064 nm light into a device under test. I need something with stable polarization so ...
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Why -20dB is taken as the standard rejection ratio for optical mode rejection in multimode waveguide?

In case of multimode waveguide to demonstrate perfect mode rejection, I saw researchers use boundary of -20dB. If mode power at output is less then -20dB, it is considered as fully rejected/filter out....

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