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.

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What would a laser beam's E-M waves actually look like if you zoomed in?

I am trying to understand how a real world beam of laser actually reflects the physics description of oscillating electromagnetic waves. So say we are looking side on at a vertically polarized laser ...
6
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2answers
413 views

Good introductory papers and books on laser physics and pulsed lasers

I am looking for good introductory papers and/or books on the principles of lasers. In particular, I am interested in pulsed laser technology. I understand that Gould, R. Gordon (1959). "The ...
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73 views

What are the practical consequences of “approximate” quantum cloning with a stimulated emission cloning machine?

Say I build some stimulated emission-based cloning machine for photons (e.g. some active laser medium). Alternatively I could do cloning via interference, e.g. a linearly polarized photon could be ...
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34 views

Is “microbunching” in a free electron laser limited by the Pauli exclusion principle?

As I understand it, a free electron laser can basically be pictured as a synchrotron light source with an undulator which by the particular setup causes the electrons to self-attune so that they ...
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26 views

3 mW laser dangerous [closed]

I bought a laser for airsoft. i want to know how dangerous it is when I aim at people(there is a chance I hit thier eyes) on the sticker it says it is <3mW and has a wavelenght: 635-670nM. (class ...
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59 views

How organic impurities in the air affects laser?

We have a Nd YAG laser pumped Optical Parameter Oscillator in our lab. A technician came to our lab (my professor called him for its maintenance) and while he was working on it, he told me that ...
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5answers
9k 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 ...
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2answers
66 views

Modeling the free space propagation of laser beams using Fourier transforms

I am trying to model the propagation of a laser beam in free space. I have an initial field $E_{in}(x,z=0)$ (a Gaussian beam) and need to find the fields at other points on the optical axis $E(x,z=d)$ ...
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2answers
54 views

How is photon time of flight/range over sub-millimeter distances measured?

I was reading a paper that described how the force a low-thrust torsion pendulum was measured. In it, the paper states a laser is bounced off a mirror and the displacement is "...based upon the beam ...
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1answer
66 views

How does laser induced fluorescence in excited atoms work?

Atomic clocks use laser induced fluorescence in order to detect excited atoms, how does this work? Apparently the clocks need to detect the states of nearly 100% of the atoms being examined. In an ...
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1answer
33 views

why not just pumping to the 3rd level directly in a 4 level laser system?

why pumping to the 3rd level in a 4 level laser system will decrease the output PL intensity?
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1answer
971 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 ...
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1answer
26 views

Optical fibre modes and intensity pattern

I shine laser line in front of one side of multimode optical fibre.Light coming out of other side is projected into wall.Whether the intensity pattern seen on wall is same as the mode of propagation ...
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2answers
119 views

Cylindrical Fresnel Lens Focus Problem

How to focus beam from the fresnel lens on a flat surface. In my case, instead of producing the light beam, I am receiving the light beam. So, the beam comes from the right and then focuses at a ...
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1answer
25 views

Does it take a lot of energy to heat metals up?

Why does it take a lot of energy to heat metals? And to do it quicker it requires much more energy? What about the use of lasers would that be an efficient process that is quicker and requires less?
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44 views

Rotating a Gaussian Beam

I need to see how the phase fronts of two gaussian beams interact when they intersect with each other. The two beams are tilted towards each other so that they intersect each other at their respective ...
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3answers
69 views

Can stimulated emitted photons be absorbed?

Typically a stimulated photon will be one of a pair with its stimulating photon. If the leading photon is absorbed by a particle in the ground state, will it then be re-emited by the stimulated ...
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2answers
52 views

Can one stimulate emission of a photon with an energy different from the emitted photon?

Suppose I have a three-level system with $E_0$ the ground level, $E_1$ the intermediate and $E_2$ the upper level. In thermal equilibrium they will have a certain probability distribution according to ...
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3answers
63 views

Proper and rigourous derivation of Gaussian beam?

Gaussian beams are known solutions to the Paraxial Wave Equation: $$ \frac{\partial^2 \Psi(x,y,t)}{\partial^2 x} + \frac{\partial^2 \Psi(x,y,t)}{\partial^2 y} = 2ik\frac{\partial ...
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0answers
21 views

Energy conversion efficiency of Q-switched laser?

This is kind of an elementary question, but since i cannot find a reliable source on this i wanted to ask what is the formula for energy conversion efficiency? I know efficiency is calculated as ...
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2answers
263 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 ...
2
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0answers
105 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 ...
3
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3answers
71 views

Stimulated emission and No cloning theorem

I have a little trouble with the simulated emission. I know of the no-cloning theorem which states that it is not possible to duplicate any state. One the other hand, I know about the stimulated ...
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1answer
33 views

Estimating quantum efficiency of gated avalanche photodiode

I have a photon counting system that uses a gated avalanche diode to detect single photons. The repetition frequency of the gates is $f_1$ and the temporal gate width is $\tau_1$ (so the duty cycle is ...
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1answer
18 views

What is the difference between emission wavelength and lasing wavelength?

I'm reading an article on liquid crystal lasers and they're saying periodicity determines lasing wavelength and cavity geometry determines emission wavelength. What is the difference?
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2answers
365 views

Rocket propelled by a giant monochromatic laser

I am preparing for my quals and stumbled across the following problem, and although it only requires undergraduate-level physics, I feel I can't piece everything together. "A rocket of mass $m_0$ is ...
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2answers
599 views

Is single photon perfectly monochromatic?

Now, we do have equipment to generate single photon at a time, and LASERs are nearly monochromatic. While typing the question, am realizing that successive photons in case of single photon ...
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3answers
408 views

Will a prism widen a monochromatic beam?

The representation of the experiment which demonstrates that white light consists of many colors, invariably shows that the beam of white light is broadened inside the prism and is some what more ...
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1answer
715 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. ...
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1answer
112 views

Laser beam position using galvanometer

In 3D printing techniques like SLA and SLS use lasers for solidifying a cross section / layer of the model that is printed. These machines, as far as I know, use XY laser scanners to project the laser ...
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1answer
109 views

Help with the Heisenberg relation in Gaussian wave

In short laserpulses there is a minimal product of the frequency width and the pulselength for Gaussian pulses $\tau \cdot \Delta\omega \geq4\ln2$ this is the fourier boundary. So I know it origins ...
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1answer
26 views

Laser excitation of Phonon Modes

Can a laser only excite optical modes? The name appears to have historical significance in terms of the sodium ion, but I presume it must be true when looking at the dispersion relationship (the ...
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4answers
222 views

Does the speed of medium affect the path of light?

Let's say I shine a laser from a stationary medium into a moving medium (suppose the water is moving very quickly) perpendicular to the interface and back to a stationary medium like this: (Note: ...
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1answer
25 views

plasma pressure initial condition

The authors in the paper below did a simulation of plasma plume evolution from a laser heated metal target. They used compressible transport equations and ideal gas EOS for Ar. I am having difficulty ...
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2answers
78 views

Conservation of energy (or lack thereof) in Doppler cooling [duplicate]

I did not find my question answered elsewhere, so here it is. I'm doing a project in my first optics course, and we are reading a bit about Doppler cooling. I understand that a laser is tuned to a ...
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6answers
6k views

Why do lasers cut? Is this a case of light acting as matter?

All I found in Google was very broad. From a physics models perspective, why can photons emitted from a laser cut? Does this cut mean that the photons are acting like matter?
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2answers
27 views

Is Initial Coherence a Problem in Experiments?

In experiments, or optical setups, is the initial coherence of lasers something to be concerned about? You can calculate interference patterns, but those generally rely on the phase shift between the ...
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Photobombing without app used by Harley Davidson

Here we see a photobombing trick, used by Harley Davidson. They achieve to incrust a logo on a photo you take. The logo is invisible with naked eyes and only revealed on the photo you take. How does ...
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174 views

From power of a laser beam to electric field amplitude

In my experiment, I use a laser beam with wavelength $\lambda=894 \text{nm}$ for some magnetic resonance experiment. Right now, I'm doing some calculation using Quantum Mechanics, which requires the ...
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0answers
14 views

Are there examples of “loss-less” Forster Resonance Energy Transfer (FRET)?

When I think of a Forster Resonance Energy Transfer (FRET) process, I typically imagine the initial excitation of an absorbing chromophore with a photon followed by the subsequent emission of a lower ...
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1answer
45 views

Is glass considered as a linear optical medium?

My research, which is mainly related to communication, involves the use of optical sources (mainly lasers). However, my background in photonics and optics is not yet solid, so my question might be a ...
2
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1answer
45 views

What is the amplifying medium in a laser diode?

I know it seems like a trivial question, but I can't seem to find the answer anywhere. So - what is the amplifying medium in a laser diode? Meaning: In a classical laser resonator, there a substance ...
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2answers
60 views

What makes a material a good lens for CO2 lasers?

I read on Wikipedia that zinc selenide and germanium make good lenses for $\mathrm{CO}_2$ lasers. My question is, Why?
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1answer
157 views

How to calculate loss due to Gaussian beam divergence of a laser going through multiple lenses?

To better explain my question, I will need to give a brief description of the configuration used in 2D MEMS switches. So, the next figure shows a configuration of a 2D MEMS switch, a light beam ...
2
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1answer
79 views

In what applications are lasers necessary vs. just convenient?

I’m trying to understand, given the wide array of current laser applications: Which applications actually require laser characteristics, as opposed to just use lasers because they are the most ...
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3answers
537 views

Why use lasers for intense, localized heat instead of some other light source?

Lasers are used in various industrial processes that need intense, localised, heat (3d printers and laser cutters come to mind). My question is: why use lasers? There are many other (cheaper, ...
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4answers
485 views

Why isn't V. A. Fabricant given the credit for the discovery of the laser?

In another question here I asked for help in finding old Russian papers in physics and as an example I gave the founding papers on the laser by Basov and Prokhorov (from 1945 and 1954). In an answer ...
8
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1answer
1k views

Why do we see laser beams?

A laser produces a coherent beam of photons with particular $\mathbf{k}$ and $\mathbf{\omega}$. So, if there is no particular $\mathbf{k}_0$ directed toward our eyes, why do we see laser beams? I ...
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0answers
38 views

Resonance condition in confocal cavity

In a confocal cavity, a beam traverses the length of the resonator 4 times between two transmissions along the same ray. . For example, in the above figure, path difference between two beams that ...
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3answers
746 views

Lasing in a 2-Level system?

What exactly is the difference between 2-Level, 3-Level and 4-Level systems? Why can we not achieve stimulated emission in a two-level system using optical pumping?