Light Amplification by Stimulated Emission of Radiation. A means of creating coherent light by either driving an atomic or molecular transition in an optical cavity or firing a beam of electrons through an undulator.
3
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2answers
101 views
Why is the photon emitted in the same direction as incoming radiation in Laser?
When an atom “lases” it always gives up its energy in the same direction and phase as the incoming light. Why does this happen? How can this be explained?
How does the photon generated because of ...
1
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0answers
16 views
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 ...
0
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0answers
12 views
How does optical phase modulation produce photons with different frequencies?
The classical description of electro-optic modulators is an index of refraction that depends on the applied voltage. For example, for a sine modulation $\sin(\Omega t)$, a monochromatic laser of ...
0
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1answer
38 views
The units of gain and number of atoms in population inversion in a laser
I am following my university course notes on amplification in laser media, and have come across expressions for the gain of a medium, but the notes are not exactly rigorous... The expression given for ...
3
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3answers
102 views
Do laser beams interfere noticeably with each other?
I want to arrange some red lasers along a 90 degree arc of a circle, aimed towards the center of the circle. When their beams hit the opposite side of the circle, will I notice any interference ...
1
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2answers
50 views
Selectively visible laser beam with a controllable means
How can parts of a laser beam be made visible while others left invisible using something electronically controllable (for example, another laser beam crossing it, or a magnetic field, or heat, etc).
3
votes
1answer
69 views
Three polarizers, 45° apart
If light is passed through two polarizing filters before arriving at a target, and both of the filters are oriented at 90° to each other, then no light will be received at the target. If a third ...
0
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1answer
42 views
I want some information about population inversion in graphene & build laser with this theory
I have read the paper
Theoretical Study of Population Inversion in Graphene under Pulse Excitation. A. Satou, T. Otsuji and V. Ryzhii. Jpn. J. Appl. Phys. 50 no. 7, pp. 070116-070116-4 (2011).
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0answers
36 views
Time reversed laser
Recently, I read an article on time reversed laser. I don't know why they call it a time reversed. I have a doubt that why they use two laser in the device. And what is an anti-laser?
The device ...
0
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2answers
191 views
New infrared laser weapon made by the USA - How does it work? [closed]
I have seen this post:
New infrared laser weapon, the Laser Weapons System, could shoot down drones or disable ships: US Navy
You can watch the video as well. that exhibits a laser weapon which can ...
1
vote
1answer
58 views
how laser interact with atoms?
I am reading a book introducing basic concept of laser. It is pretty shocking to me that people can generate beam with almost all photons in the same state. In the book, it said that a two-level atoms ...
1
vote
1answer
92 views
Demonstrating Quantum effects with home experiments using green diode laser [closed]
I would like to preform home experiments to demonstrate quantum effects to my kids. I need a list of experiments on Laser photons that could be easily conducted at home to demonstrate quantum ...
2
votes
2answers
82 views
Spot of my light on the moon
This is a funny question, but worth answering. The distance between the moon and the Earth is 384,400 km. The speed of light is 299792.458 km/s. It will take 1.3 seconds (Approx.) for my laser beam to ...
3
votes
1answer
108 views
Gamma Ray LASER Theory and Technology
I am aware that a similar question has been asked by someone else in the past, but in a very general form. Due to the physics interest and technology, in this question I put emphasis on the detail of ...
5
votes
1answer
77 views
Free Electron Lasers (FEL) and limits on laser wavelength
Free Electron Lasers are based on Synchroton coherent radiation when a collimated electron beam suffers trajectory curvature due to a strong bouncing magnetic field inside an undulator.
Free Electron ...
2
votes
2answers
57 views
Optical trapping problem
Can we make light slower by applying optical trapping (I mean applying laser beam to lower the speed of light)?
2
votes
1answer
83 views
Factors that make beam divergence worse after refocusing
A beam of light of width $W$ and wavelength $\lambda$ with divergence that is diffraction-limited is refocused with an optical element placed at a distance $D$ from the beam source. Will the refocused ...
0
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0answers
21 views
Calculating population ratio for radiative transmissions in lasers
I'm trying to understand how the ratio of population is related to the energy gap between two energy levels. If an emission of a wavelength at 550nm is given off at room temperature (293K), then what ...
2
votes
2answers
126 views
Would a laser with four possible energy levels be better than three?
I'm wondering about achieving population inversion for a laser. I learned that without an active medium, it's not possible to create a laser with only two energy levels, but it would be possible with ...
1
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2answers
82 views
Quantum yield and spontaneous decay
I'm trying to figure out how many atoms are decaying spontaneously in a span of 2 seconds. Let's say that the quantum yield is 0.45, and that the lifetime "τ" (tau) is 10 microseconds.
Then I found ...
7
votes
2answers
152 views
What exactly is the difference between a sychrotron light source and a free electron laser?
Cyclotron radiation is radiation emitted by a charged particle being bent by a magnetic field. The only difference between cyclotron and synchrotron radiation is that the latter occurs at relativistic ...
2
votes
1answer
104 views
How would one generate Brownian light? What would it look like?
When light is an equal mix of all visible frequencies, we call it white light.
By analogy, sound that is a mix of all audible frequencies is called white noise.
For sound, there is an additional ...
9
votes
2answers
709 views
Is the “How to break the speed of light” minute physics video wrong?
I am referring to this video, on YouTube, by minutephysics, which has quite a lot of views.
In the video it states that if you flick your wrist while pointing a laser that reaches the moon, that the ...
1
vote
2answers
332 views
laser pointer class III and potential eye damage
we just bought a green laser pointer on Ebay and had a discussion about the safety. The laser is low end chinese one (5 USD, free shipping :-) ) and the seller says this:
Green Laser Pointer Point ...
1
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0answers
29 views
What methods exist for us to measure the position and momentum of atoms that make up molecules?
In reference to this paper, http://iopscience.iop.org/1355-5111/8/1/014, we are able to localize atoms using homodyne measurement. Would it be too naive to consider we can measure the position of ...
4
votes
3answers
167 views
Counterpropagating beams in a ring cavity lasers
Ring cavity lasers usually has a intracavity element like a optical diode to forbid standing wave pattern and, consequently, spacial hole burning and related instabilities. So, my question is: why to ...
3
votes
0answers
42 views
Photon pumping in Laser
Let's consider a ring laser where the laser must pass through the gain material before it is sent toward a partially reflective surface $\ R=1-T $. The other mirrors are perfect reflectors with $\ ...
5
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3answers
316 views
How do “holographic plates” work?
I asked a question about laser stage lighting over at Audio Video Production, and received an excellent answer that explained that laser clusters are generated from a single beam via something called ...
0
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2answers
210 views
about waveplate and polarization
I have a throlabs half- and quarter-wave plate with rotation plate. There shown the angle scales and a line denotes the fast axis. But what does the angle mean? I do some research and someone said the ...
6
votes
1answer
330 views
Is the time reversed laser really a laser?
I'm looking at the time reversed laser and I was having trouble understanding why we call this device a laser. To me this device is more like the absorbers found in FDTD codes, something like a CPML.
...
3
votes
1answer
266 views
Doppler cooling limit vs recoil limit
I was discussing laser cooling in class today and I understood that the main principle of the process is to tune a laser to a frequency lower than the absorbtion frequency of the atom and so only the ...
6
votes
2answers
475 views
Why do green lasers appear brighter and stronger than red and blue lasers?
This is mostly for my own personal illumination, and isn't directly related to any school or work projects. I just picked up a trio of laser pointers (red, green, and blue), and I notice that when I ...
1
vote
1answer
76 views
Ideal four-level Gain Medium (or just any old gain medium)
What exactly is happening in a laser's gain cell when the irradiance is greater than the saturation irradiance?
Also can someone offer a clear conceptual treatment of the gain-coefficient and its ...
3
votes
1answer
258 views
Beam splitters- Direction of use
There are two cases I'm asking about. The square in the middle is a cube beam splitter in the same orientation for both cases. We are looking at the beam splitter from the top. In the first case, ...
0
votes
2answers
2k views
Free Optics Simulation Programs
I'm having an extremely difficult time finding an optics program that is easy to use and offers accurate physics simulations. I'm not asking for much, I just want to be able to simulate a laser going ...
0
votes
1answer
149 views
Calculating laser wavelength/power to cause emission of light in a gas?
It's been a long, long time since I've had to worry about electron excitation levels and band gaps. Please forgive (and correct!) my terminology and misconceptions. I've also posted this in the ...
3
votes
2answers
166 views
Redirecting light beams from beam splitters
I'm doing a project where I am taking a laser beam and sending it through a beam splitter. As I understand, approximately 50% of the light will go pass through and 50% will be reflected. So this means ...
11
votes
6answers
1k views
Tried to do the double slit experiment, failed. Why?
I tried, and failed, to do the double-slit experiment. I thought I had a good experiment setup, but obviously I was wrong. Can anyone offer some insight in what I might have done wrong? Most of ...
3
votes
4answers
179 views
Water Jet Cutter and Laser
I watched a video of "Glass cutting" which uses a Water Jet Cutter. It was said that Cutting glass simply by machines would eventually crack it... So, They're using grains of sand (by placing a sand ...
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3answers
214 views
A Different Lasing Medium [closed]
Powerful lasers are highly intense, diverge negligibly and are also coherent. These radiations are emitted through partially reflecting mirrors after simultaneous reflections within the lasing medium. ...
4
votes
1answer
95 views
Optical laser pumping and reflectors
Let's say we are building Nd:YAG laser.
It is optically pumped by some linear xenon flash lamps, it absorbs light around 750nm and 800nm, and emitted light is at 1064nm.
The question is why doesn't ...
2
votes
0answers
86 views
Macroscopic chromodynamics
Lately I've been reading about gamma ray lasing phenomena, and I've been wondering about the applications of this.
More concretely, the above fantastic question led me to wonder if we could somehow ...
1
vote
1answer
104 views
Does Combining Lasers Add to Their Power?
For example... If I had a 2W green laser, a 2W red laser, and a 2W blue laser, could I combine them using crystals to form a 6W white laser? Or is that now how it works? If not what would be the ...
1
vote
1answer
112 views
Why does heterodyne laser Doppler vibrometry require a modulating frequency shift?
On the wikipedia article (and other texts such as Optical Inspections of Microsystems) for laser Doppler vibrometry, it states that a modulating frequency must be added such that the detector can ...
4
votes
1answer
51 views
what general physical arguments discredit induced emission of nuclei?
trying to read a bit about "quantum nucleonics", i've encountered this rebuttal from people at Livermore that induced radiation stimulation of Hafnium nuclei is possible. Something that catches my eye ...
3
votes
1answer
340 views
gamma ray lasers?
Is it really possible in the foreseeable future to create a gamma ray laser? I've read these two articles on Wikipedia:
the Hafnium controversy
Induced gamma emission
It sounds pretty amazing, ...
0
votes
1answer
74 views
Density and statistical models for visible air dust
If a laser beam is looked at from the side versus a dark background, a sparkling effect can be seen caused by dust particles in the air hit by the beam.
Is there any simple model or coarse ...
0
votes
2answers
79 views
Image contrast as function of exposure for a CCD detector
In a laser interferometry experiment, we project a pattern of interference fringes onto a CCD sensor. For best results, we want good contrast between the bright and dark fringes, and we carefully ...
21
votes
2answers
418 views
Why does laser light not affect glowing materials?
I have this childrens rubber ball which glows in the dark after it's exposed to light. I "charge" it with a flash light then play with my dogs at night. I thought to try a very intense green laser, ...
4
votes
2answers
200 views
Optical Drive Physics
I have been recently wondering how is data stored on and retrieved from optical devices like CDs, DVDs, and Bluray. What makes these different storage types different from each other?
