What are "Optical Modes" actually? Single Mode and Multimode fibers explained!

Link to detailed note showing MMF derivation:
github.com/Ole...
Numerical simulation of electric field in SMF and MMF
• Optical fibers, single...
How mode mismatch leads to power loss:
• Splice Loss
Link to python Notebook for solving mode equations:
github.com/Ole...
Brief overview of multimode fibers:
www.rp-photoni...
Explanation of modes in rectangular waveguides (lectures 18-23):
• Lecture 18: Waves in g...
Additional derivation of modes in fibers:
prefetch.eu/kn...
Lectures on SMF and MMF:
• Optical Fiber 101: Und...
• Optical Fiber 101: Usi...

[@yourfavouriteta]

A link to the Python notebook I used for generating the mode solution plots is available in the description along with additional sources on modes in waveguides!

[@naymulhasan8559]

Excellent... I was looking for similar video 1 week ago. Here finally i have found it. Your videos have been helpful to me.

[@yourfavouriteta]

I am happy to hear that! Please feel free to share them with friends and colleagues :-)

[@labibbidabibbadum]

Nobody else should be allowed to discuss fibre on KZbin. Thank you... incredibly clear and well explained.

[@yourfavouriteta]

I will take the compliment, but please do check out some of the other channels explaining fiber optics :-) Les' Lab has great experiments demonstrating nonlinear effects in fibers and was kind enough to give me a shout-out in a recent video of his.

[@labibbidabibbadum]

@@yourfavouriteta thanks, will check. I've come across a few that I felt seemed wrong, or unscientific. Yours made sense to me in a way I could translate from mech eng principles of physical systems, rather than glossing over why there are modes and just taking vaguely about rays bouncing about inside the fibre...

[@yourfavouriteta]

@@labibbidabibbadum. Maybe the reason is that other students are simply brighter than me, but it always bothered me when teachers would rush into derriving mathematical concepts and drawing abstract diagrams without spending much time setting up the problem. In my view, Physics is the study of *causality*; how the change in one thing causes other changes. The true art is to develop causal explanations of observable phenomena, preferably in plain English. Math gives us a way to quantify how large certain changes will be, but without a step-by-step, intuitive explanation of the causality a mathematical model of a physical system (even if it's correctly derived) is just a black box that spits out correct answers. In short, we have to know both "why?" and "how much?", but my impression is that the latter is often over-emphasized at the expense of the former.

[@farbe123]

Thanks for your work!

[@yourfavouriteta]

You're welcome!

[@GeoffryGifari]

Lets say I have a mode with bilateral symmetry (like the one at 5:37). If the electric field profile is rotated around the propagation axis, would it still be the same mode?

[@ToddYarbrough-nd9ty]

The math in this video is way beyond my comprehension, so I will frame my question around a principal I think is related. Could the antennas representative of "center-frequencies" as a loose interpretation? In a Microwave transmission system let's say the wave guide has a resonance calculated at 6 GHz. The maximum transfer of power will be at 6 Ghz. However "harmonics" of 6 GHz will also resonate at maximum power transfer such as 3 Ghz and 2 GHz. Is this a decent interpretation of modes in fiber optic transmission?