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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Can Sagnac effect be observed in coiled, rotating electrical cables conducting electric signals?
Can Sagnac effect be observed in coiled, rotating electrical cables conducting electric signals, in a similar way to that observed in coiled, rotating optical fibers? And if so then who demonstrated ...
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Will light of 405nm wavelength behave in a single mode (SM) fiber , in multimode manner?
Since the wavelength of 405nm is substantially shorter than the wavelengths of 1310-1550nm, and since the ratio of the diameter of a single mode fiber core to the wavelength, at 405nm, is several ...
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What is the connection between Ray (Geometric) optics and Electromagnetic theory optics in fiber optics?
I am currently reading about fiber optics and wave propagation in fiber optics and encountered the following part of Gerd Keiser's Book :
according to the diagram shown, its a general case when the ...
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Understanding the use of Group Velocity Dispersion Optics
I am a bit confused on the topic of GVD. Most information I read on the topic tells me something like this: "GVD means that the group velocity will be different for different wavelengths in the ...
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How do optical fibres work with high critical angles?
The critical angle is given by:
c = arcsin(n2 - n1)
For a typical optical fibre, it says on the web that refractive index (n2) for cladding is higher than that of the glass core (n1) but it's only a ...
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Why does an optical fibre employ total internal reflection instead of just reflection? [duplicate]
I learnt that an optic fibre uses the concept of total internal reflection (TIR) to transmit data at high speed, but why do they not use just simple mirrors instead of using refractive medium and ...
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Waveguide allowed modes | Transverse resonance condition
Consider a planar waveguide for example. The guiding index is $n_f$, and the cover and substrate indices are $n_c$ and $n_s$ respectively. Let the waveguide propagate along z, and have a height $h$ in ...
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Effective Refractive index of a mode less than that of the cladding refractive index?
Can the effective refractive index be less than the cladding if the waveguide width is very small. For example for the case of a ~100 nm waveguide.
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In which part of the Sagnac fiber optic setup will the light undergo the most intense interference?
Let's assume we have a Sagnac setup consisting of a 1310nm laser, 2X2 coupler injecting light into two opposite ends of a single mode fiber loop, and a photodiode receiving the light from both ends of ...
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Will light, from two different (but identical) lasers injected into one end of a long fiber, come out form the other end with the same polarization?
Two beams of light from two lasers of the same type, with the same wavelength but different polarization, are coupled with 2X1 coupler into a 100m long single mode regular fiber. Each laser can be ...
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Laser beam quality problem: The laser beam showed very different during using the CCD testing directly or using the M2 measurment machine
Recently, we encountered a problem with the laser beam profile characterization, where two testing methods showed two distinct results of the beam profile of the same laser system.
When we used a CCD ...
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Problem measuring local reflectance through objective lens
Measuring the reflectance of copper substrates using only reflection probes gives an expected reflectance (orange plot). But when an objective lens is used to focus the incident light, I can see the ...
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How to collapse telescope image cone into an optical fiber?
I have an application where a telescope will be receiving light from a laser source. I would like to couple the output of the telescope, which is the image cone, into an optical fiber. Does anyone ...
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How does an endoscope form the image?
I am trying to do ray tracing for an endoscope, but I don't see how it could form a sharp image that could be viewed at the eyepiece.
In the diagram the box in the middle is the "fiber", but ...
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Dependency of attenuation in optic fibers on wavelength of light
I have read and heard that scattering, and attenuation in general increase with frequency.
However, in an experiment we did as a part of our course, we found that attenuation constant for light of ...
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How does MEMS low insertion loss fiber optic switch work? [closed]
I'm currently looking for a low insertion loss fiber optic switch to be able to change the light source of a spectrometer. Since this will be used in harsh conditions, I was hoping to find one with no ...
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How does the change in cavity length effect the interferometric frequency of a Fabry Perot cavity?
I'm working with FBG-based Fabry Perot interferometers, considering three FBGs in series to create 2 FP cavities. I'm confused about the following two things and cannot seem to get clear answers from ...
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Why the tapered optical fiber which dipcoated with rGO didnt give significant changes of voltage inside Photodetector?
I already cut it carefully the jacket out from cladding, and then use ethanol to rub the cladding so the core can be dipcoated with PVA-rGO solution.
Now I can see higher voltage depends of how much ...
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Optic Fiber Gyroscope Within Its Frame
I understand why the fiber optic gyroscope works as well the calculations for the time discrepancy between the beams travel time, but only as observed from out side the ring, "watching" it ...
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Why can't a wave in the cladding of a waveguide phase match to a guided wave?
What is the physical reason behind why a wave in the cladding of a waveguide cannot phase match to a guided wave?
I read that the most common solutions to coupling waves to a guided wave is to use ...
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Veracity of light field propagation simulation method (Combined Split-step Fourier and BPM)
When trying to simulate light propagation in three spatial dimensions and one temporal dimension I encountered a method given in this thesis. Here (on page 32), it is proposed to do a BPM within a ...
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SRS is reduced by increasing the bandwidth of the OC in high power fiber lasers generally. What happens if the bandwidth is increased too much?
Several articles suggest, in a MOPA configuration high power fiber laser, the SRS can be mitigated by increasing the bandwidth of the OC FBG. How to determine the optimized bandwidth of such FBG? Does ...
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Could anyone explain me about forming core mode and defected mode in photonic crystal fiber?
I need some information about upper mode and lower mode in photonic crystal fiber sensor.
What conditions should be provided for core mode and defected mode to be formed?
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How do I calculate the numerical aperture and refractive index of the waveguide?
I have a step-index optical fiber with a core and a cladding. I need to calcuate the numerical aperture and refractive index of the core (assuming the laser beam is gaussian). So the numerical ...
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How to expand light from fibre optics?
I am building a spectrophotometer for my robotics science club. I am using fibre optics cable to transport emission signal from the sample to spectrometer,next it is projected on the refelctive ...
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The output laser power of fiber amplifier fluctuates up and down with the increase of pump power
I was engaged in the research of 2um thulium-doped fiber laser. During the experiment, I found that when the oscillator seed light was injected into the amplifier stage for amplification, the output ...
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Where can I find the derivation of $V$ number (fiberoptics) from analysis of the Maxwell’s equation?
This is from Optics (5th ed.) by Hecht, p. 209. I was studying fiberoptics and this parameter called $V$-number came up. Also there is another term called the normalized propagation constant, b which ...
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Does carriers lifetime introduce any dispersion to a LED diode emitter?
I'm asked to calculate the maximum chromatic dispersion coefficient D for which an optical cable is able to transmit at a 100 Mbps bitrate working in SMS.
The maximum bitrate is given by
B≤1/2∆τ, ...
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Difference between seed and pump in chirped pulse amplifier
What is the difference between to seed an optical amplifier (such as Chirped Pulse Amplifier) and to pump it with a laser source?
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Can a fibre preserve the shape of the light being transported through it?
Can some fibres retain the shape of the light being transported through them?
If I emit radiation towards a sample (in the shape of an "S") and this is reflected back into a fibre, will the ...
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Total Energy of an Asymetric 3x3 Coupler
In our experiments, we are using a 3×3 fibre couplers with light as part of an interferometer-setup. This coupler isn't symmetric; it's phase relation of every output is unequal to 120° and the ...
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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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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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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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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 ...