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 ...

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11 views

Why would longer distance between collimated lenses improve coupling efficiency?

Im coupling 1550nm output from a single-mode lensed optical fiber to a standard SMF using a pair of collimating lenses, matched to the NA of the respective fibers. However, I find that by increasing ...
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28 views

Why does not the optical fiber break? [duplicate]

Glass is a very fragile object. So why does not the optical fiber break? Everytime I take them, I am worried about this problem.
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1answer
22 views

Why does some light escape when in a fiber taper?

I am working with fiber tapers and i noticed that some light escapes from the tapering region and i am quite curious. I am using a 500 micron plastic optical fiber and i managed to stretch the ...
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1answer
31 views

Why do higher modes propagate more in the cladding of an optical fiber than lower modes?

I am trying to understand the theory of inter-modal dispersion in optical fibers. It seems quite obvious that if higher modes have a greater angle of incidence in the fiber than lower modes, the path ...
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0answers
36 views

473 nm light through a single mode fiber designed to operate between 1500 and 1600 nm

Can we send light with 473 nm through a single mode fiber designed to operate between 1500 to 1600 nm spectrum? The radius of the fiber core is 4.25 micrometer, NA=0.12 and the single-mode cut-off is ...
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1answer
113 views

How I can launch light into PM fiber

A polarization maintaining fiber preserves the linear polarization of the light at the output, the light at the input must be linear polarized to see signal at the photodetector... However I can't see ...
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0answers
13 views

Why is forward brillouin scattering difficult to observe?

Generally we talk of only the backward Brillouin scattering. And I just know forward scattering is difficult to observe? Why is it so? Does it have something to do with phonon life time? Is it ...
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1answer
61 views

Calculating the beating length of the directional coupler

I want to determine the coupling length needed to achieve a certain power coupling coefficient of a directional coupler. Recently, I read a paper titled "Ultra-compact high order ring resonator ...
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1answer
133 views

What will happen if I transmit 850nm signal through a 1300nm optical fiber? [closed]

We prefer 1300nm optical fiber over 850nm optical fiber because later one is more efficient. So am selecting 1300nm optical fiber. But I want to know the possibility of using same cable to transmit ...
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1answer
41 views

How can I make an optical circulator?

I need to a single mode 1550 optical circulator at my lab. I have a varied supply of components, but no circulator. Any idea how I can make one myself? Perhaps using coupler and isolator? Thanks. -D ...
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1answer
127 views

Snell's law demonstration

I'm a bit confused about a Snell's law demonstration. I'm reading Communication Systems from W. Tomasi. In the chapter 11, the author applies the Snell's law to θent, and -here comes my problem- he ...
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2answers
127 views

Will microwaves interfere with data transfered through fiber optics?

Do fiber optical cables used for broadband signals of Internet get any interference due to any nearby microwaves generated in mobile phones? I learned that fiber optics are used to transmit data in ...
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0answers
75 views

How to calculate the Gain of EDFA amplifier? [closed]

I have co-propagating pump laser and tunable optical signal and I want to measure the Gain of EDFA Amplifier from the Optical Spectrum Analyser (OSA). I have measured first the signal power without ...
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1answer
55 views

Will light leak into a side glow optical fiber?

I am looking into some possible applications of side glow optical fibers (plastic). Will side glow fibers "drive" adjacent fibers? That effect is undesired.
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0answers
29 views

What is the minimum bend radius of a square optical fiber on a microfluidic chip interface?

I want to make a microfluidic chip with colorimetry cuvettes with 100um square optical fibers coupled to the side of them. They should bend at a 90 degree angle to exit the side of the chip in a ...
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3answers
310 views

How noisy are photon detectors?

I have a single photon detector and $N$ photons per second arrive at the detector. Then something happens and the number of incoming photons per second changes by the factor of $\alpha$. So now ...
2
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0answers
80 views

How does the Darma - Smart Cushion work? Explanation of the new fiber loop ring-down spectroscopy

How does the Darma - Smart cushion monitor your sitting position and obtain the breathing rate, body movements, and BCG (Ballistocardiography) signals? The creators say that they accomplish this by ...
2
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0answers
62 views

Why the Caustic of a circle is the most bright curve in the circle?

Caustic of a cirle is the envelope of light rays reflected by a circle, which is the most bright curve in the circle. But why? Here is the picture shows the Caustic of a circle.
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1answer
91 views

What is the ratio power in core/ total power in an optical fiber?

I need to plot a graph of power_core/total power in optical fiber with respect to $V$ Number: searching on the internet I got this formula: ...
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0answers
882 views

Effective refractive index calculation of fiber core

Can someone pls explain what is effective refractive index of fiber core and how to calculate it theoretically? Suppose the fiber core refractive index=1.4446 and cladding refractive index is= ...
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2answers
110 views

Phase shift in back-reflection generated at the mating point of two fibers

If you have light traveling from glass to air at normal incidence, e.g., in an optical fiber with the endface open, the Fresnel reflection coefficient would roughly be $R = |(1.5-1)/(1.5+1)|^2 = 0.04$ ...
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2answers
99 views

Increase path length for a photon with two mirrors vs optical fiber

Is it possible to build two mirrors in vacuum such that a light pulse (single photon) gets refleted many times in order to increase the distance it travels? For example like that? Say I want the ...
2
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1answer
66 views

Optical fibre modes and intensity pattern

I shine laser line in front of one side of multimode optical fibre.Light coming out of other side is projected into wall.Whether the intensity pattern seen on wall is same as the mode of propagation ...
3
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1answer
47 views

What happens if we use an optical fibre for light at a different wavelength than the one specified on the fibre?

Say the fibre is for 700 nm, and we shine light at 1064 nm into it. Would it change the mode? The polarisation? The beam shape (i.e. introducing ellipticity in the beam)?
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3answers
146 views

Proper and rigourous derivation of Gaussian beam?

Gaussian beams are known solutions to the Paraxial Wave Equation: $$ \frac{\partial^2 \Psi(x,y,t)}{\partial^2 x} + \frac{\partial^2 \Psi(x,y,t)}{\partial^2 y} = 2ik\frac{\partial ...
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2answers
291 views

Why does a single mode fibre have a cutoff wavelength?

I earlier had a doubt based on ray theory that light must reflect and so all wavelengths should propagate through SMF. This Q/A Single-mode fibers and ray-theory of light does specify that we have to ...
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2answers
77 views

Difference between single mode and multi mode optical fibres?

What is the difference between single mode and multi mode optical fibres? First off, I guess that by modes we mean the spatial modes of the electric (or magnetic?) field right? Now: what makes a ...
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1answer
16 views

Light Focus Guider [closed]

How can I easily guide a focused light source to a different location without losing focused light intensity? If there is an item, where can I buy this? I heard about fiber cable, but I do not know ...
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1answer
85 views

How to calculate transmission of photonic band gap fiber?

How to calculate transmission of hollow core photonic fibers (multilayer fiber and 2D band gap fiber)? Which books/article you can recommend ? I see that comsol can do it, but is there a model that ...
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1answer
26 views

Optical devices for micro meter photons?

Are there all the common optical devices like beam splitters, mirrors, polarizers, fibers, etc for photons with a wavelenght in the range of micro meters? If so, how broad can the bandwidth be for ...
6
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2answers
271 views

Single-mode fibers and ray-theory of light

I have read ray-theory cannot be applied to single-mode fibers. Why? I know rays are kind of an approximation to describe the real behavior of light, and electromagnetic theory and photonics are ...
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2answers
314 views

Numerical aperture (NA) of an optical fiber

Numerical Aperture (NA) (for fiber optics) is usually used to denote the acceptance cone for a multi-mode fiber. Does NA also describe the expansion of light emitted from the end of a fiber? I have ...
2
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2answers
81 views

Photon dispersion in an optical fiber

What is the law of spatial dispersion of a photon in an optical fiber? Say I have a femto second photon ($\lambda$ around $700\,\text{nm}$) with gaussian shape ($\sigma = c\cdot 1\,\text{fs}\approx ...
2
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2answers
83 views

Mean free path of a photon in a fiber

Is there a way to calculate, or a reference table I can to look up which provides the average distance a photon travels before it encounters an electron and is absorbed or re-emitted in a fiber optics ...
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1answer
127 views

Graded Index fiber

In the following picture of a graded index fiber two different modes are depicted. One is a higher mode which is propagating towards the core-cladding interface and one is through the higher ...
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0answers
46 views

What is the difference between dispersion and differential mode group delay?

I want to know what exactly is the differential mode group delay in optical fibers, is it the same thing as dispersion?
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1answer
450 views

How to calculate loss due to Gaussian beam divergence of a laser going through multiple lenses?

To better explain my question, I will need to give a brief description of the configuration used in 2D MEMS switches. So, the next figure shows a configuration of a 2D MEMS switch, a light beam ...
11
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1answer
806 views

Can a burning laser be directed through fiber optics?

Can a laser powerful enough to cut(100w for example) be redirected using fiber optics ? What issues need to be considered? To be clear it should retain the ability to cut after exiting the fiber.
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0answers
279 views

Is there an equation to calculate efficiency of an optical fiber to transmit sunlight for length of 4 m

I want to transmit sunlight over a distance of approx 4 m via optical fiber. Ideally I want to light up the whole house with sunlight. I was reading that the largest diameter for an optical fiber may ...
2
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1answer
106 views

Mode groups in an optical fiber

I know what modes in an optical fiber mean but what are exactly mode groups in an optical fiber? From what I read until now, I have the impression that modes that have close propagation constants ...
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5answers
200 views

Single mode fibers

Is it possible to focus white light into a single mode optical fiber? I thought no because in order to focus it should be a solution to the Helmholtz equation but I am not too sure about it. Also ...
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1answer
112 views

Characteristic quantities in Fiber optics

I'm having trouble finding typical quantities in fiber optic communication. In particular, what kind of powers are generally used (or what is the minimum that fiber optics receivers can detect ...
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4answers
902 views

Does optical fiber preserve the angles of incoming light?

I am reading up on optical fibers and there's one thing I haven't understood yet: Does an optical fiber preserve the angles of incoming light? For example, if we light two LEDs in front of an ...
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0answers
25 views

Resource about Supercontinuum Generation in Fibers

I would like to consult a nice reference that explains the theoretical background of SC generation in optical fibers in detail but more or less self-contained. I would also like to have your opinions ...
3
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2answers
221 views

Fiber optics with broadband, incoherent light

I wonder if someone could help clarify waveguiding with broadband, incoherent light please. If we take a telecomms fiber, which is single-moded above ~1.4 μm and couple a laser beam in, we assume ...
4
votes
1answer
181 views

How does a 2D MEMS based optical cross-connect control its mirrors?

Concerning fiber optics, I'd like to know how a 2D MEMS based optical cross-connect is able to switch optical signals. I've read that these mirrors are controlled with electrical signals to be either ...
2
votes
1answer
300 views

Solar energy and optical fiber

I'm not really good at science or physics, just wanted to ask about the idea (doesn't have an opportunity to test this). Will this scheme work and what can be its efficiency?(The goal is to make ...
1
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1answer
358 views

E and H fields created by fiber optics?

When an EM wave travels down a conductor, it creates and electric and magnetic field around (H) the wire and normal to (E) the wire. My question is, when light travels down an optical material such ...
5
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4answers
3k views

Efficiencies of Coupling Light into a Fiber

I am in AMO Physics and work a lot with optics. I just wanted to get an idea of what coupling efficiencies one "should" get in a "reasonable time"* by coupling light into a fiber using different ...
6
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4answers
4k views

Focusing light into an optical fiber cable

I'm trying to focus light from a flashing light lamp throught two lens into a optical fiber cable which is around 0.8cm in diameter. flashing light: a bulb and then covered by a glass of 7.5cm x 7cm ...