Questions tagged [waveguide]
206 questions
27
votes
4 answers
Is the EmDrive, or "Relativity Drive" possible?
In 2006, New Scientist magazine published an article titled Relativity drive: The end of wings and wheels1 [1] about the EmDrive [Wikipedia] which stirred up a fair degree of controversy and some claims that New Scientist was engaging in…
user8616
8
votes
1 answer
Plane wave expansion in cylindrical coordinates
I am trying to solve scattering problem in 2D and got to expand the wave function in cylindrical system which comes out to be Hankel function. Can you tell me how to expand the plane wave $\exp(i {\bf k}\cdot {\bf r})$ in terms of Hankel function,…
nagendra
- 325
8
votes
1 answer
Reconciling total internal reflection and the evanescent Wave
I understand that light is guided in a dielectric waveguide via total internal reflection. My question is regarding the origin of power contained in the evanescent field traveling along the direction of propagation.
From Fresnel equation we get…
Kenaish Al Qubaisi
- 81
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7
votes
3 answers
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 this excites the only mode, which is the fundamental…
Wostwl
- 135
6
votes
1 answer
Validity of flat coupling approximation in input-output theory + why is it called Markov approximation?
In standard input-output theory, we model the interaction between light and a two level system by the following hamiltonian which assumes rotating wave approximation:
The interaction between a classical electric field, polarized along a single axis:…
StarBucK
- 1,688
6
votes
3 answers
Physical origin of transverse waveguide modes
I've been working with multimode lasers for a couple of months now, and whilst I have a good understanding of what their output looks like and what longitudinal modes are, I continue to be absolutely baffled by the idea of transverse modes, which…
roxy-k
- 61
6
votes
1 answer
Evanescent wave coupling
In my optics course we have observed that in several applications, such as prism coupling of modes in an optical waveguide, coupling between two waveguides, attenuated total internal reflection (or frustrated internal reflection) in spectroscopy,…
JackI
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5
votes
3 answers
Waveguides and Maxwell's Equations
Background
In many textbooks on electromagnetism, the sequence in which topics are introduced are generally as follows -- electrostatics, magnetostatics, electrodynamics, wave propagation in free space, and wave propagation in confined space, in…
5
votes
3 answers
Why do we use wires/conductors to transport energy?
I am currently studying Maxwell equations and I learned that copper wires are essentially just wave guides for EM waves. Why do we not use an insulator to guide the wave and transport the energy which is in the fields? Because a conductor is lossy…
user2276094
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5
votes
2 answers
Why is Erbium Doped Fiber Amplifier (EDFA) preferred over Erbium Doped Waveguide Amplifier (EDWA)?
Why is Erbium Doped Fiber Amplifier (EDFA) preferred over Erbium Doped Waveguide Amplifier (EDWA)?
The question has been asked from an engineering point of view, but obviously I would also be interested in Physics of it. Is it just because of the…
Nix
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5
votes
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Why the fields of the quasi-TEM mode of microstrip line tend to concentrate in the dielectric as frequency goes higher?
A microstrip line is a waveguiding structure as shown below:
Because of the inhomogeneity, the fundamental mode of propagation is a quasi-TEM mode, which means that the z components of the E and H fields are much smaller than the transverse…
George C
- 173
5
votes
1 answer
Boundary condition on $\mathbf{B}$ to describe resonant cavities from waveguides
In Jackson- Classical Electrodynamics when resonant cavities are discussed (8.6, page 252) (but also at page 7 here or at page 19 here) the explanation is made by saying that the solution is the same of a rectangular waveguide, which we can suppose…
Sørën
- 2,727
5
votes
2 answers
Can one make a propagating field along a waveguide only have longitudinal/transverse components?
We know that in free space, a propagating electromagnetic wave is always transverse. However, along a dielectric waveguide, the propagating wave can have longitudinal components. The exist of the longitudinal component makes the group index of…
Xiaodong Qi
- 646
4
votes
1 answer
Why is TE mode preferred to TM mode in the optical waveguide in silicon photonics?
I recently started learning about silicon photonics, focusing on its usage in the high-speed interconnect.
Most papers I've been reading so far use optical waveguides choosing TE00 as the dominant mode, and I have not seen any papers or references…
Emm386
- 177
4
votes
0 answers
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 would like to use polarization maintaining fiber. I…
awade
- 41