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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48 views

Ray Theory of Light [on hold]

Can ray theory be used to explain wave nature of light? True/False ? Explain it with reason.
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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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31 views

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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26 views

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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1answer
24 views

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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1answer
43 views

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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Temporal period to frequency conversion (optical cavity)

Why is it that the Finesse and resonance width of a cavity calculated in time domain is different from that calculated in frequency domain? Here is a temporal signal that I recorded with a photodiode ...
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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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What can be done to a laser' setup to increase its slope efficiency?

Having a fibre laser, whose setup consists of a pump diode, a YDF and of a fully reflecting mirror parallel to the fibre, what can I do in order to improve the slope's efficiency without adding any ...
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DIfference between pump diode power and fibre's input end power?

I am reading some measurements done on a fibre laser, and the first data shown is the Current v Power table of the pump diode used in the experiment. After that, a fibre is added to the system and a ...
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What characteristics of a fiber laser can I get from the input, output and unabsorbed pump data?

I aligned a pump diode with a fiber laser and added a dichroic mirror in front of the laser to separate the pump light from the light radiated from the fiber. This way I was able to analyse the power ...
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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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1answer
36 views

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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What is air band and band gap in Photonic crystal structure?

want to know the meaning of air band of photonic crytal
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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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what is bolch optical mode?

I have read some papers(https://arxiv.org/ftp/arxiv/papers/1206/1206.4342.pdf) where the word ''bolch mode'' used. Now I want to know what kind of optical mode this is and how or why it is generated?
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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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What causes the upper limit on wavelength in optical fiber?

It's well known that a most given waveguide modes have a cutoff wavelength above which the mode is no longer supported. At low wavelengths, more modes are supported. But what happens at high ...
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1answer
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What angle does light leave a 400micron fibre if it entered from a single mode fibre (0.14NA)?

We would like to connect a single mode coupled laser to a 400micron fibre. Ideally, we'd like the light to come out of the 400micron fibre at all angles or close to the maximum divergence angle, ...
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What is the most measurable electromagnetic wave coming from a small, dark, and not necessarily hot object in sky? [closed]

Optical fibers are recently used to generate some spectroscopic surveys of the universe map based on some projects such as DESI, MOONS, SDSS-V, etc. The current fibers are often sensitive to visible ...
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Why are bend losses higher at higher wavelengths in fiber optic cables?

I have been researching the effect of wavelength on macro-bend losses for my extended essay (a 4000 word paper on a subject of your choice, high school level) on fiber optic cables. I asked this ...
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Fiber optics sensos rise time to bandwith

I am researching the fiber optic detectors trying to figure out how they obtain very high bandwidth of about 10 GHz which is essentially 10 Gb/s. When I look up detectors by fiber optic companies, I ...
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1answer
59 views

How to calculate the dispersion parameter of a Fiber?

I am writing a presentation about DCF Fibers. From many articles i am reading, the dispersion parameter of Fibers are given. But it is not shown how it has been calculated. For example ,in this ...
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What is the Brillouin Stokes power?

I know what is the brillouin scattering and i also know what is the Stokes power. Do someome knows what is the Brillouin Stokes power ?
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1answer
31 views

What is the gain control technique used in optics?

In optics, it is said that The gain bandwidth and gain flatness of Amplifiers are enhanced utilizing gain control techniques.What techniques are they referring to ? I know the automatic volume ...
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1answer
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Why are bend losses higher at higher wavelengths in fiber optic cables

I have been reading about fiber optic cables for the past few months, specifically about bend losses. It is often mentioned that bend losses are higher at longer wavelength light and indeed this is ...
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1answer
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Is the length of a distributed Bragg reflector $= λ / 4$ so that one mirror is at a maximum?

Am I correct in my assumption that the ideal length for a distributed Bragg reflector (DBR) is the wavelength of light over 4, so that one of the mirrors is at a maximum for each photon... and this ...
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1answer
136 views

Refractive index of Noble Gases at high pressure

How/where can I find(estimate) the refractive index of noble gases like argon and krypton? How does the refractive index of argon and krypton depend on the pressure, specifically high pressures of up ...
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Does the speed of light transmission in an optical fiber change with the refractive index of the surrounding material?

I am learning about distributed fiber optic sensors where properties along the cable can be continuously determined, eg. temperature from Raman backscatter shift at a resolution of ~0.1 C at ~1 m ...
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Coupling in single mode polarization maintaining fiber

I want to couple light (785nm,~80mw) into a polarization maintaining fiber PMJ-3HPC3A-780-5/125-3AS-1-5-1 (5nm core diameter) with a coupler installed on the laser head (Sacher TEC 400 laser) .The ...
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Is it possible to have an optical version of a greenhouse? With optical fibers?

Optical fibers transport light within them using internal reflection, but the light only enters from one end of the fiber. Is it possible to somehow have light entering from the sides of the fiber (...
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56 views

Dispersion and wavelength

Why does dispersion increase with wavelength? If I understand correctly, refractive index is decreasing with wavelength. As a result, greater wavelengths are traveling faster. How does this cause the ...
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1answer
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What influences the variance of signal transmission speed?

I'm currently thinking about the various sources that influence time when it is synchronized with the NTP protocol. One of them is the physical layer (OSI-model). When sending a bit over a cable, ...
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what is the advantages of using 2-μm operating wavelength light in sdm/mdm technology? [closed]

Most of the work have been done in the communication band but recently there has been emerging interest in extending the operating wavelength of communication system to the short-wave infrared (2 μm). ...
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2answers
261 views

Modes in optical fibers

I am trying to understand the modes in step-index optical fibers and I saw that they say the electric field distribution in the core and cladding is as bellow. my question is that which component of ...
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1answer
303 views

what is effective index method which is used to solve modes in rectangular waveguide? [closed]

I actually want to know the basics of effective index methods for solving the optical modes in slab/rectangular waveguides.