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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What are some of the best materials to use for building a fiber laser safety enclosure of 1060nm - 1085nm?

I have gotten a 30W JPT-LP Litemarker Fiber Laser which has a wavelength range of 1060nm - 1085nm. Before even thinking about using it, i want to build an enclosure for it to increase the level of ...
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Understanding the Light propagation through multimode fibers

I'd appreciate it if anyone could help me clarify the theory behind this. I am playing with this code found on Github, https://github.com/wavefrontshaping/pyMMF to simulate the light propagation in ...
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Question about fiber to chip coupling in silicon photonics

I asked a similar question earlier (How is the fiber alignment done in pluggable optical transceiver module (e.g., QSFP-DD)?), but few things are still not clear to me, so I'm posting another one here....
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How is the fiber alignment done in pluggable optical transceiver module (e.g., QSFP-DD)?

I recently started learning silicon photonics. After reading a few books, I understand that a single-mode fiber (especially non-polarization-maintaining fiber) supports two degenerate guided modes. ...
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How to find integrated power of a optical signal using wavelength amplitude graph?

I have a wavelength amplitude graph as shown below. This a screenshot captured from optical spectrum analyzer. From the image I can see what is the power at each wavelength. But, I would like to ...
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What is the best way to couple diffuse light into a single-mode fiber?

I understand the requisites to couple a laser beam into a single-mode fiber, including mode-field diameter and numerical aperture. However, when trying to couple diffuse light into a single-mode fiber,...
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What Does the Electromagnetic Field Around Tapered Fiber Optic Cable Look Like?

I am making a graphic that includes a fiber optic cable with a tapered portion. I would like to show in the graphic the EM field within and around the cable. I have a general idea of what the field ...
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Choosing the right lenses for optical fiber

I need to measure optical emission of lanthanides when excited with X-ray, so I have to problems, difficult to align (X-ray radiation) and poor signal. In this case I need to choose some lenses to ...
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Why do optical-fiber based interferometers work?

Let's start with my basic understanding with interferometers (in general): a beam is split in two, travel in different arms, recombined coherently resulting in an interference (constructive, ...
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How to achieve uniform gaussian profile? Beam profile has grainy/multimode pattern, EO says it's due to different emissivity of each phosphor atom

I'm required to make a jig that measures the divergence angle of a collimated beam. The setup is straightforward as shown below. The single-mode fiber optic cable, collimator & NIR camera are the ...
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Does the response of a fiber-optic sensor to strain increase as temperature increases?

Fiber-optic sensors etched with Bragg diffraction gratings are used as temperature sensors in many applications. They are also used to measure strain. As the strain or temperature increase, the peak ...
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How to choose the right lens for projecting a certain area to a fiber optic

I am looking for a lens to magnify a certain area so that it can be captured by a fiber optic. Specifically, I want the fiber optic to capture a certain object, which requires it to be at a distance ...
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How does a photodetector work more specifically?

I’m studying how fiber-optic communication works. To transmit a signal, you need a transmitter that converts electrical impulses into luminous and a photodetector that performs the reverse operation. ...
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What are the difference between step-index and graded index fiber?

I was starting to study optical fibers and I came to the chapter: Classifications of optical fibers. Here I read about singlemode and multimode fibers, regarding the latter he explained the difference ...
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How about optical fiber without cladding and directly coated?

How about optical fiber without cladding and directly coated? I have got some answers from here, but how about optical fiber without cladding and directly coated? and the coating material have a ...
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How can I collimate a laser beam of 100 wavelengths in vacuum?

Before collimating, the beam will have diverged a bit to a radius of 5cm, the range of the wavelengths is 1400-1600nm and I don't want to lose more than 30% of initial power. I'm asking in general how ...
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How to calculate the Full Width at Half-Power (FWHP) at the output of two SMF and DCF connected in cascade

Assuming a Gaussian pulse with a wavelength $\lambda$ and $FWHP_i$ , a SMF with dispersion $D_{SMF}$ and length $L_{SMF}$, a DCF with dispersion $D_{DCF}$ and length $L_{DCF}$ How can I calculate the ...
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Data transmission through optical fiber and copper wire

I read the following in one reference: A copper wire (twisted pair), the link traditionally associated with low bit rate transmission, is still in use in the modern data centers transmitting data at ...
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Working of the optical fibre

I read about the mechanism of an optical fibre. It works on the basis of total internal reflection. But for total internal reflection it is necessary that the incident angle is more than the critical ...
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Wavelength-dependence of optical elements in integrated photonic circuits

I am interested in integrated photonic circuits or silicon photonic circuits. In the long run, I would like to analyze these circuits using a rigorous and analytical mathematical approach, taking the ...
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In fiber wave guide we only consider transverse (TM,TE,EH) modes of laser. Why not we consider londitudenal modes?

Laser beam guiding through fiber.
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How to find peak power at 1550nm using an optical meter?

I have a setup of tunable laser source at 1550nm connected to a spectrometer(Can't publish the name of spectrometer). The spectrometer has a range of 1510-1595 nm. The graph shows wavelength vs ...
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How to implement a very precise polarizer inside a fiber-based setup?

A tricky question: I need to use polarizers with a ~5 arcmin precision inside a PM fiber-based system. What are some (hopefully cost-effective) ways of achieving this? The setup works with linear ...
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How is certain area of waveguide becomes visible to user?

I was reading an article and came across this image As shown, image becomes visible to eye after reaching a specific area of the glass. But how does it work? Why is it being reflected at such a weird ...
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Why dielectric waveguides support hybrid modes and metallic waveguides don't?

Can anyone explain me qualitatively, why dielectric waveguides (core and infinite cladding) support hybrid modes ($E_z$ and $H_z$ components in the guided wave) while metallic waveguides cannot. I am ...
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Field at exactly cutoff of optical fiber

Can anyone give a clear qualitative explanation on what is the field inside and outside an optical fiber at EXACTLY cutoff?
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Why is a Small Coherence Length Desired for Fiber Optic Gyroscopes?

For interferometric measurements based on the Sagnac effect, typically a light source is injected into counter-propagating paths of a fiber optic coil. The rotation of this coil of fiber optic cable ...
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How fast, based on the laws of physics can the Internet be? [closed]

Assuming the actual physics, optics, signal processing and similar, how fast can we increase the 'speed' of the Internet? I know the limit would be $$v \le c,$$ but are there some other limits: ...
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Experimental detection of Anderson localization of light in 3D vs 2D

I have a question about the experimental realization of Anderson localization of light. I am a theorist, and have not worked much in optics, so please bear with me. Anderson localization of light in ...
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Drawing digital signal from analog signal

I was doing a question related to analogue to digital conversion. Here's the question, Draw the digital signal corresponding to the analogue signal given below. Assume that the system has a bit rate ...
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Why is it possible to couple multiple wavelengths into a single mode optical fiber?

I'm quite new to the mode theory, but as I understand, single mode fiber should only allow a single pattern of wavelength + polarization. I'm assuming a non-modulated non-coherent light (a white LED, ...
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Coupling a light source into an optical fiber ring

My question is whether the following scenario is realistic. Imagine coupling a source of photons (say a laser) into a ring made of an optical fiber using a y-junction. (see picture) If the ...
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Why are daylighting fibre optics so much more inefficient than other fibre optic cables?

Comparing Optical Fiber Light Tubes losses and regular Fiber Optic Losses, there seems to be a large disparity. The light tubes reach 100m, whereas the regular ones go for kilometers. I've tried to ...
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How to derive group velocity dispersion (GVD)?

I'm trying to arrive to the following expression to group velocity dispersion: $$\text{GVD} = \frac{\lambda^3}{2 \pi c^2} \frac{d^2n}{d \omega^2}.$$ I know that GVD can be expressed as: $$\text{GVD} = ...
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Dispersion / group velocity in tapered fiber

dispersion in fibers are defined as: $$D=-\frac{2 \pi c}{\lambda^2}\ddot{\beta}$$ where: $$\ddot{\beta}=-\frac{1}{v_g^2}\frac{dv_g}{d\omega}$$ where $v_g$ is group velocity Does the group velocity / ...
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Difference of refractive indices of fiber layer

recently I received a simulation related document from a fiber manufacturer. The simulated fiber has an inner core, outer core and a cladding. The strange thing about the document is, that in the ...
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Zero-dispersion wavelength

Please help me understanding the zero-dispersion wavelength in fibers. I found this wiki-article on the topic. Accordingly: "In a single-mode optical fiber, the zero-dispersion wavelength is the ...
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Maxwell's equation along a curve and Evolution of the polarization vector

So here is the setup: There is a coiled cylindrical wire. At each point on its axis, we define a tangent direction $\hat{t}(s)$, and a normal $\hat{n}(s)$ and binormal $\hat{b}(s)$, $s$ is a ...
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Why is fiber optic not affected by EMI?

If light is an electromagnetic wave, why is it not affected by electromagnetic interference? I've heard it's because fiber optic do not use electrical voltages. Can someone go deeper into the subject?
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Existence of $\mathrm{HE}_{11}$ mode in optical fibers for $v \to 0$

In a step-index optical fiber, the eigenvalue equation for the $\mathrm{HE}_{11}$ fundamental mode, under the weak guidance approximation, can be written as $$\frac{J'_n (u)}{u J_n (u)} = - \frac{K'_n ...
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Normalization of Phase Noise / RF Power Spectrum to 1 Hz RBW

I used a Rohde & Schwarz Phase Noise Analyzer to take some phase noise and RF spectrum measurements. All in all, I'm trying to compute the linewidth of a laser from a measurement. I cannot detail ...
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Fiber bragg grating simulation

I am trying to simulate a FBG with a windows based software. It would be great if someone suggest a proper software for me. Thanks all!
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Phase shifted Optical Fiber Bragg grating Response

As we know there is a narrow notch in the reflectance spectrum of a Phase shifted FBG. We have Bragg condition for reflected band of any uniform FBG. My question is that, does anyone know any relation ...
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How do non-mechanical solid-state optical switches work?

I am currently looking for a fiber-optical switch (FOS) in order to be able to change the light source of a spectrometer. As this will be used in harsh conditions, I was hoping to find a FOS with no ...
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Effective refractive index can be equal zero?

Can someone please explain the cases that the Effective refractive index $n$ on it can be equal zero? Does such a situation even exist? I am trying to solve an ordinary differential equation to find ...
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How to determine the effective index of the fundamental mode?

Suppose I have an optical fiber, the cladding refractive index n1 = 1.53 and the that of the core is n2 = 1.55. How to estimate the effective index? Is it right in between the two values?
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Creating Different Colours From A Pulsed Monochromatic Light Source

I am currently learning about fibre optic communications, which I understand use pulsed laser sources to generate a "bitstream" to send through the fibre using some form of pulse width ...
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Ray Power Equation for Bent Fiber Optics

I came across this equation while reading the book, Optical Waveguide Theory (by Snyder and Love) on page 182: where P(0) is the initial power from the straight fiber, R is the curvature radius, ρ is ...
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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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