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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How can I bond a fiber to waveguide grating coupler?

I am wondering how can I bond a optical fiber to waveguide grating coupler. Should I use some type of glue? Or should I fix the fiber with a translation stage?
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Relationship between Optical Power output and luminous intensity

I have an LED with the following specification which I'm using for oxygen saturation measurements. Here the optical output power is given as >1.2mW for RED LED and >0.5mW for IR LED. How to ...
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Can a spectrometer detect interference pattern?

I am not sure whether this is the correct place to ask, otherwise, please point me to the appropriate platform. I have been reading about fibre optic interferometric sensors and notice that most ...
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Interference of Visible Light in Fiber Optics

I read this paper (the last sentence of Section 3.1). It is stated that in fiber optic interferometric sensors, the interference pattern cannot be detected if visible light is used because most fiber ...
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Fibre optic -physics

What is different between the lost of coupling and efficiency overall coupling ? I know both of them (power out/power in)e.g (5%) that means is 5% light transmission and 95% lost.
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Modal dispersion in optical fibers

I've got a couple of doubts regarding modal dispersion (with respect to optical fibers) What's the difference between intermodal and intramodal dispersion? How does intermodal dispersion affect ...
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Single mode fibre

I've got a couple of basic doubts about single-mode optical fibers - a) Why do single-mode fibers have lower attenuation than multimode fibers? b) Why do light rays in single-mode fibers travel in a ...
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Evaluating equation for cutoff condition of cylindrical dielectric waveguides

To determine the eigenvalues $u$, $w$ of a mode in a dielectric cylindrical waveguide (an optical fiber, for example), the following equation must be evaluated when $w \to 0$: $$\xi_1^2(u) - \xi_1(u) \...
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Why the optic axis of an crystal should has a proper direction; why it cannot be a single line? [closed]

In many books it is written that the optic axis of a crystal is a direction rather than a single line! I really cannot understand what is the necessity of the direction and why I cannot say that it ...
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Collimation issue with an DIY echelle spectrograph

I am trying to make an educational echelle spectrograph using easily available materials, basically in a cardboard box. An echelle grating (36 lines/mm) needs another prism to do a cross dispersion ...
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Why fiber optic cables looks colorful?

I wanted to know why fiber optics look green or blue, isn't it that it uses total internal reflection, so light shall remain in it? I think may be it's not monochromatic.
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What is the formal definition of Coupling efficiency

Does anyone knows the formal definition of Coupling efficiency? I have been reading the term in photonics devices and optics. I have been searching for it, but I could not find any. Thanks for the ...
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Is it possible to optimally transmit solar radiation by a system of multiple optical fibers?

As we all know, if an optical fiber is designed with the right material and properly bent, light can be transmitted along the fiber with very little attenuation. Figure 1 shows the interaction of ...
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Why does a prism spread its “output” out over space, not time?

I'm having fun learning about the physics of optical networks at a new job. It's fun connecting elementary physics learned so many years ago with how they're leveraged today in practical application. ...
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Time independence of light in optical fibers

The propagation of light in optical fibers is governed by the equation $i\frac{\partial A}{\partial z} = \frac{\beta_2}{2}\frac{\partial^2A}{\partial T^2} - \gamma|A|^2A$ where $A(z,T)$ represents the ...
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Optical trapping over fiber

I poured a droplet that has 1.55 refractive index (RF) over a fiber that has core and cladding with (RI) 1.45 and 1.4 respectively, and I the molecules aggregated over the fiber, known that because ...
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Derivatives of the propagation constant in optical fibers

In many books on nonlinear fiber optics, the Taylor series expansion of the mode-propagation constant $\beta$ is performed about a frequency $\omega_0$ at which a pulse's spectrum is to be centered. $\...
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Numerical aperture of a multimode optical fibre

The refractive indices of the core and cladding of a multimode optical fiber are 1.62 and 1.52 respectively. Calculate its numerical aperture if the optical fiber is placed in (a) water (b) ice (c) ...
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Confinement factor for an optical fiber

I was reading the chapter about optical fibers of "Fiber - optic communication systems" and I have read this statement: The fraction of the power contained in the core is given by the ...
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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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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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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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