Photonics is the science of creating, moving, and detecting photons
Questions tagged [photonics]
217 questions
14
votes
3 answers
What happens to the non-axial photons of a laser cavity?
When a laser cavity is pumped, the axial photons are reflected back and forth by the cavity mirrors and so contribute to stimulated emission, but the non-axial photons do not have this opportunity. What happens to these non-axial photons?…
The Pointer
- 939
7
votes
2 answers
Band theory of Photonic crystals
I have a basic question about the band structure of photonic crystals.
If I have a periodic potential, then Bloch-theory tells me that the bands yield the energy spectrum of the Hamilonian which is described in terms of some quasimomentum $k$…
Sascha
- 127
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5
votes
1 answer
Iridescent duck and photonics in nature. Why duck's head is only green?
We all know and adore pure beauty of mallard male:
I know that such iridescent colours are usually a result of feathers forming a photonic crystal with layers of air sandwiched between layers of feathers. However as I know (e.g. from observing a…
user46147
- 3,114
5
votes
1 answer
Homogeneous gain saturation and single-longitudinal-mode lasing
I am currently studying Laser Systems Engineering by Keith Kasunic. Chapter 1.2.1 Temporal Coherence says the following:
Whether or not multiple axial modes will lase depends, in part, on the cavity-mode spacing $\Delta \nu_a$ in comparison with…
The Pointer
- 939
5
votes
0 answers
Books recommendation to understand Quantum Confined Stark Effect
I am starting a PhD on a photonic component involved with QCSE. The problem is that I have a Master degree in electronical engineering, not in fundamental physics, and I need to understand the QCSE in GaAs QW for my PhD.
What are the basic books you…
an1052
- 1
4
votes
1 answer
What happens if obstacles (walls) been put where destructive interference occurs in double slit experiment?
If photon doesn't have probability to be in dark (destructive interference) area, what will be the effect of adding obstacles (walls) in the dark (destructive interference) area for the double slit experiment?
Wael Khatib
- 99
4
votes
2 answers
Are two localized single-photon states always invariant under the particle exchange?
In a text book for quantum communication, I learned that one generates optical pulses (wavepackets), each of which contains only one photon. For instance, the state of two wavepackets are described by $|H\rangle_1|V\rangle_2$, where $|H\rangle_1$…
Ketty
- 49
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
2 answers
Scattering vs Stimulated Emission
I am currently reading Practical Flow Cytometry, fourth edition, by Howard M. Shapiro. The author says the following when discussing scattering:
Scattering, which explains both reflection and refraction, typically involves a brief interaction…
The Pointer
- 939
4
votes
2 answers
Non-monochromatic (multi-wavelength?) lasers
I was recently doing some reading on lasers, and I came across the fact that truly monochromatic light is impossible, which then obviously implies that truly monochromatic lasers are impossible. But this leads me to wonder:
If truly monochromatic…
a24914ad
- 43
4
votes
1 answer
What is a good introductory textbook to Laser Safety?
I was looking for a good textbook about Laser Safety (e.g. protection glasses design, distance of risk calculation, laser classification...). I can't find a complete book with these informations, could you recommend one for me?
muserock92
- 163
4
votes
2 answers
Propagation of a flat-top laser beam in free space
I have spent some time looking at how to design a field mapping system that turns a Gaussian beam profile into a top-hat beam. However, it would also be very useful to have a very sharp super-Gaussian profile for a different experiment.
I have…
Jaywalker
- 2,413
3
votes
2 answers
Light always travels in straight line but what about diffraction?
It's said that light always travels in straight lines. Even when reflection happens, another light ray is generated by electrons in the mirror , which cancels out the incident light. Refraction is also caused by superposition of light made by…
Shaurya Kad
- 603
3
votes
1 answer
How can the inverse of stimulated emission be distinguished from "normal" absorption?
A simple system with two energy states can absorb an incoming photon (of adequate energy) to get excited, and it can relax by either spontaneously emit a photon afterwards or get stimulated by another incoming photon to emit an identical photon.
But…
Tobias Kienzler
- 6,950
3
votes
2 answers
What is up and down conversion in photonics?
I have heard the terms up and down conversion in photonics/photovoltaics articles. What do the terms mean?
Kit
- 1,483