Questions tagged [optical-fibre]

A flexible, transparent, fine fibre made of extruded silica to function as a wave guide to transmitting signals through light

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The influence of fiber length stability in coherent fiber communication

The length of optical fiber tend to change along with the environment. I wonder how do the coherent optical fiber communication (like QAM, QPSK, etc.) successfully recover the phase of the signal, ...
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Various types of multimode fibers

I have recently been studying fibers in school. I know there are 2 main types of fibers, singlemode and multimode. I know that single-modal are the most used for long journeys and because they have a ...
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Marvell 88E6097F switch and AR8033 PHY

I'm trying to design a 6-port Fiber switch. For this I chose the MARVELL 88E6097F which is an 8-port switche+3GE. My problem is that the CPU (IMX8M-P) comes out from the SOM with a PHY (AR8033). Is it ...
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Optical Receivers and Amplifiers

I have been doing some past papers for a university module I am studying. I am not from an electrical engineering background so don’t really know how to attempt the question attached. I would really ...
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The field in a waveguide at exactly the cut-off frequency

Can anyone explain to me qualitatively, what kind of field exists inside a waveguide at EXACTLY the cut-off frequency? I would be grateful if an explanation was given about waveguides with metalic ...
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How can I tell whether a waveguide supports hybrid modes or not?

When studying metallic waveguides, it was taken for granted that the TE and TM (and potentially TEM) formed a complete set, that is, any electromagnetic field in the waveguide could be written as a ...
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The speed of light is 3*10^8 m/s and data transmission rate of optical fiber is ~100 Tb/s, how do we calculate data transmission rate?

How do we calculate data transmission rate? Is there some formulas that is involved? Fiber optic cables beat copper in this department, and it isn’t even close. Fiber optic cables are made of tiny ...
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Converter RS232-Optical

Based on the configuration below: [Network Element 1] ----(RS232 TX)----[Converter RS232-Optical]-------[Converter Optical-RS232]----(RS232 signal) ----> [Network Element 2] From the network ...
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From delay to distance?

I need to estimate the distance of a link having only delay values. How can I do that? I need to estimate this distance for ethernet and optical fiber links. I thought of doing it using the ...
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Using fiber optic cable for power transmission

Could someone knowledgeable explain why fiber optics could or could not be used for power transmission large or small? The formula for power in optical fiber is shown below. X is photons per second, ...
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Working on live optical fiber

I was recently asked if there was any negative for working on live optical fiber, and I was not sure of the answer. I imagine the answer is don't do it, but aside from specialized glasses to protect ...
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Waveguides and optical fibres

Why at microwave frequency we prefer rectangular waveguides while at optical frequency circular waveguides (i.e. optical fibres). Can we have rectangular optical fibres.
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USB 3.x to Ethernet then Ethernet back to USB 3.x IC a.k.a usb over ip

Hey all I’ve been looking around a lot for a company that has a type of USB 3.x over IP. The ones I only see are not ICs but full blown products. These products cost $250+ so I’m looking to see if I ...
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Fiber optic transceiver for lower speeds

I am trying to figure out if a QSFP-DD transceiver can break out 8x 10G lanes if I make/use a 1:8 fiber optic breakout cable. It seems like most Transceivers are rated for one speed only, so if I get ...
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Fiber Optical and 80Gbps MTP/MPO?

I am trying to get a cable solution to output 80Gbps of data. My FPGA is trying to input/output data. It has QSFP-DD cages. Fiber SFP+ cables (50um and multimode) need to interface to this. From my ...
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QSFP-DD to 8x 10G SFP+

I am trying to use a QSFP-DD port on an FPGA to breakout and interface with 4 or 8 SFP+ ports. I am curious if this is possible. From my research online, it seems like this all depends on the module ...
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Why do we have a limited bandwidth in electronics?

I've been looking around a bit on optical communications and it is said that the main advantage in using optical communications, namely optical fibers, lies in the gigantic bandwidth available, when ...
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How to interface TMDS signal with optical tranceivers at low cost?

Not like this which is about protocol, this is about physical. The HDMI2.0 (18Gbps) fiber optic HDMI cables on market seems to be "cheap", like<$100. Although optic fibers are very cheap ...
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How does a repeater convert light from a fibre-optic cable into binary?

I'm just starting out in Computer Science and currently learning about transmission of data in fibre-optic cables. I understand fibre-optic attenuation and that a repeater will then take this light ...
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How are ground wires and OPGW connected to ground and neutral point of transformer, and to the com.system?

Note: This question is about power systems in the kV, MVA range. Many distribution and transmission systems are impedance grounded, which means that (some of) the transformer neutrals are connected to ...
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I wonder what these fibre-optic cables are used for

One cord. Two identical ends. Looks like female end would be similar to a phone style connection but it is not for phone. Black cord, two ends identical
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What is the highest possible optical output power of an SLED?

I am inquiring about this because I'm looking for a suitably high-power, large bandwidth light source for a fibre optic communication system I am designing. The distance the data will be required to ...
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Why do simple optical fibers usually support only half-duplex communication?

I'm a newbie to the subject, so a thorough answer would be very helpful. I was curious as to why simple (single) optical fibers usually don't allow full-duplex communication. To my understanding, all ...
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Can optical fiber communication be used to transmit analog signals?

I am confused because I read the LEDs/LASERS used in optical fiber have finite levels. If for instance ASK is used to transmit digital baseband data then will the LED or LASER be able follow the ASK ...
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What are these teardrop-shaped loops in power lines for?

I just happened to notice this along a road near where I live: So these were in a pair, oppositely facing, "tip" to "tip" of the teardrop. At first glance, this doesn't seem to be ...
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How do we choose refractive index value in optical fiber design?

It is known that, given two media with refractive indeces \$n_1\$ and \$n_2 < n_1\$, if rays come from medium 1 they will be totally reflected if their angle of incidence is higher than the ...
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Using QSFP28 Module at Lower Lane Rate

I have an application that requires optical transmission of 4x16 Gbps SERDES lanes over fiber. A QSFP28 module for 100G ethernet seems like a great commercial solution--it can take the four lanes and ...
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Q-value in APD photodetector

I try to calculate the Q value of APD photodetector with these parameters: $$R \hspace{0.1in} (response) = 1$$ $$M \hspace{0.1in} (magnification) = 10$$ $$k \hspace{0.1in} (ionization \hspace{0.1in} ...
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Detector for a fiber optic gyroscope

I'm a navigation engineer, so I often have to deal with gyroscopes and their measurements. Out of curiosity, I've decided to build one myself and will give it a try with a Fiber Optics Gyroscope (FOG),...
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Do we use any filter after photodiode?

In wireless communication, we use a matched filter to suppress out-of-signal-space noise. After this filtering we do sampling. Otherwise, the power of noise is infinite (practically very large). In ...
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Different ways or sensors to detect the weight on an object in a system

I am starting to gather information for a project I am excited about; my project is essentially a barbell that can detect the weight loaded on it. I will quickly summarize the function and restraints. ...
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Photodiode not working in reverse bias

I'm using a photodiode module, model: coaxial InGaAs, Gtel. I set it in reverse bias with 5V and tested it with a laser but it doesn't give any output voltage. Unfortunately I don't know the laser ...
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How optical sources having narrower spectral width gives higher data rates?

How optical sources having narrower spectral width '\$ \Delta \lambda \downarrow \$' gives higher data rates '\$ R_B \uparrow \$'? For example: Laser having lower spectral width gives higher data ...
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A few questions about the application of ethernet controller and PHY chip and SFP module

I have a question about the connection/application between the ethernet controller and PHY/SFP modules. Actually, there're so many scenarios for building up a NIC card, which makes me confused. For ...
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optical glow fiber for low-tech communication links?

Can cheap "glow" optical fiber (or other inexpensive materials such as aquarium air tubing, etc.) be used for low-tech low-speed optical communications using just simple discrete components, such as ...
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How to measure the amount of light emitted back from a fiber optic cable?

I would like to build a setup where I use a light source to emit a signal over a fiber optic cable, and then measure the amount of light that is emitted back, e.g. by blocking/opening the other end of ...
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How to make affordable DIY low-res absolute rotatory optical encoders with fibers? [closed]

I have zero knowledge of optics and want to make a very low resolution (~10°) absolute rotary optical encoder using rapid manufacturing (I have 3D printers, laser cutter, and desktop CNC). Digging the ...
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How to Work with a Optical Fiber Ribbon

I got a piece of fiber optical cable that is in the form of a "ribbon cable" (see pictures). I have seen tools and procedures for making connections on a single strand of optical fiber. I would like ...
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Nanopower Fiber Optics / MOSFET Switch

I'm a newbie at designing at the nanopower level, hence my question. In this circuit, I have plastic fiber optical inbound signal that drives D1 photodiode, whose dark current is extremely low (tens ...
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Do electronic fiber optic selector switches exist?

From my research, I have been having a tough time finding and specifying a fiber optic selector switch or multiplexer. Do fiber optic selector switches exist? Background - Simple I have an ...
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How does a fiber optic receiver converts the optical signal to an electrical signal

A fiber optic receiver needs to convert the incoming optical signal to an electrical signal so it can be sampled. How is this achieved in practice? I believe a photodiode is used, but would a ...
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Multimode to singlemode optic fiber

I'm naive in this field, but I will need to use optic fibers for optogenetics application. I already know that my question will sound stupid for the most of you, please forgive me for that. My ...
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How come optical data modulation is faster than that of electrical modulation while optical modulation is done by electricity?

why optical data is of high bandwidth that that of electrical copper data bandwidth when we use electrical signal to achieve optical data modulation ?
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Optical receiver output voltage higher than power supply

The part is a optical receiver from Broadcom. It has TTL output, but specified with a maximum output-high voltage higher than the power supply. I wonder what's special structure internal may make it ...
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Optical bandwidth and electrical bandwidth

I understand the concepts of electrical and optical bandwidths, but I encountered an example problem that used the following formula to calculate the electrical bandwidth: $$electrical bandwidth = 1/\...
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Shot noise variance of a channel for different bits

I've come across a question, where I had to calculate shot noise variance calculations of an optical link. As per the definition, shot noise in an optical channel is the current that arises from the ...
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Material dispersion in fiber optics transmission

In plain English, why does material dispersion increase with wavelength in fiber optic transmission? I am aware that refraction index decreases with wavelength increase, i.e. pulse travels faster, but ...
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How cell sites work? [closed]

In Mobile communication, how do cell sites communicate to each other to the point when they reach the cell site which is connected to the other mobile phone when I make a call . What is the medium of ...
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2 answers
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Using SFP modules from a microcontroller

I'm interested in having an embedded device send data optically. This is for test and measurement, where having conductive cables is problematic since it will perturb the measurement. The device is ...
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Fiber-optic transceiver ICs for applications other than fiber-optic Ethernet? [closed]

When we talk about fiber-optic transmission, we almost always talk about copper to fiber-optic Ethernet conversion using fiber-optic transceivers. But since fiber-optic communication is just ...
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