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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Finding the appropriate fitting function for a coherence length measurement

I'm studying Coherent Optics in Experimental Physics, and I intend to determine the coherence length of a two beam interference. To do that, I used an He-Ne laser, a Michelson interferometer and a ...
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1answer
100 views

Does this length refer to wavelength or length? [closed]

In this question: A He-Ne laser emits red light of the wave length $\lambda = 632.8\ \mathrm{nm}$ with a beam diameter of $2.0\ \mathrm{mm}$ and a power output of $1.0\ \mathrm{mW}$ [...] (d) How ...
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1answer
35 views

Why must we use mode locked lasers?

Quick question: If I have a laser cavity with a bunch of harmonics under the gain curve: Why do I not always get a pulsed laser? EG: I mean since these harmonics exist in the cavity arn't they ...
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27 views

How can I find out allowed quantum transitions?

My active element is fluorine(F), I have an energy level diagram: So, i must choose the pump's channel and find out what quantum transitions are allowed. How can i do it?
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1answer
25 views

Timekeeping , optical clocks, and precision

I am having trouble understanding something: The concept of time measurement. So I want to simply this as much as possible to get an intuitive understanding: We define the second by the time it ...
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0answers
54 views

Why is a two level laser impossible to make? [duplicate]

I would like to know why it is impossible to have a two level laser ? Indeed if I write the equations (I neglect here the spontaneous emission), I have : $\frac{dN_2}{dt}=W(\omega).B.(N1-N2)$ and ...
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1answer
63 views

What determines laser frequency?

I am studying Lasers and frequency combs - and am not quite understanding something. I understand the working principle of a laser, and thought the Laser output frequency is just the energy gap ...
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1answer
129 views

why is it that the photon incident on metastable state stimulates atom to go into ground state but not to even higher energy state?

isnt it possible that photon incident on atoms at metastable state goes to further high energy state rather than the ground state? whilist there is always that stimulated emisson taking place. why ?
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2answers
295 views

What is the amplitude of the electric field in a laser?

I'm looking for reliable informations about the amplitude (not the intensity), in volt/meter, of the electric field in a typical laser. Or in other words : what are the typical amplitudes of the ...
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0answers
17 views

What does “Polarization Gradient Cooling” mean?

I'm well versed with what "Polarization Gradient Cooling" refers to, as in how the process works and what the term refers to, but the term itself baffles me. What is a "Polarization Gradient"? The ...
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0answers
54 views

The Nonlinear Schrodinger Equation (NLSE) [closed]

I am trying to show that the NLSE: $$\frac{\partial A(z,T)}{\partial z} = -i \frac{\beta_2}{2} \frac{\partial^2A}{\partial T^2} + i \gamma |A|^2 A$$ may be cast in the form: $$\frac{\partial ...
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26 views

What's the procedure of “Chirped Pulse Amplification Process”?

We have a pump source, single-frequency green laser, with such properties:power 14w;wavelength 532nm. We have another seed source, mode-locked titanium:sapphire laser, with such properties: wavelength ...
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1answer
25 views

Diffraction pattern from laser shone on coffe-filter plastered on glass pane

I make an ordinary coffe filter wet and plaster it on a glass pane. I then shine a laser onto the filter (on the side of the pane with the coffe filter). When I do this, I see what I assume is an ...
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1answer
54 views

Range of modern laser beam

Is today there the prospect of communication using lasers a distance of approx. 50-150 light-years? If so, what is the maximum range which can be achieved with modern laser power, eg. 1000W? We assume ...
6
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2answers
216 views

Why not just pump directly to the $3^\mathrm{rd}$ level directly in a $4$-level laser system?

In a 4-level laser system, the pumping is usually from level 1 (the ground state) to level 4 (the highest-energy state). Image source Why do such schemes not pump directly to the third level? Will ...
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29 views

Light scattering - creating an atmosphere that a laser will be visible in

I need to show the beams of red, green, yellow and violet lasers 100mW Red + 40mW Green for a demonstration in a darkened room that holds 150 people. The room has sensitive fire alarms that use ...
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3answers
837 views

Laser power consumption vs power output [closed]

I have a 5 mW laser pen powered by a 1000 mAh 3.7 volt battery that takes over 2 hours to recharge. It drains it in 15 minutes. Why is it only called 5 milliwatts output if it is consuming 14.8 W?
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6answers
27k 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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4answers
5k 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?
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1answer
34 views

combination of lenses for undefined focal length

Good morning! I am not an optics specialist, but I need to know if it's possible to do what I tried to visualise in my picture. Basicly I want to merge two beams into one. I am thinking of using a ...
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1answer
58 views

How are professional laser shows done [closed]

How are professional laser shows done ? I need an explanation of the phenomenon of a laser visible in mid air ,(NOT THE APPARATUS USED which means I don't want the engineering aspect of it,I only want ...
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0answers
11 views

Can I simulate the motion of resonant scanner with a laser beam incidence and reflection using Comsol? Or I need to use different software?

I'd like to see the motion of the beam incidence onto a resonant scanner travels with 20 degrees wide. It is important to see the reflection inside a closed hollow geometry
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1answer
54 views

Can you concencrate paralel laser beams?

I've seen some videos of laser toys but they all seem to use either one laser or lens with some specific range of focus. What I was thinking is this: But it seems like it might violate the 2nd law ...
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1answer
34 views

What is the difference between ultrafast laser and normal laser?

I was reading an article of latest innovation and i came across this 'ultrafast laser' term. What is the difference between it and the laser we normally refer?
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3answers
2k views

How is squeezed light produced?

Ordinary laser light has equal uncertainty in phase and amplitude. When an otherwise perfect laser beam is incident onto a photodetector, the uncertainty in photon number will produce shot noise with ...
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36 views

Can a simple harmonic oscillator describe Rabi oscillations?

I've been trying to simulate a resonant laser oscillation of a two level atom with Rabi frequency $\Omega$ and a rate of spontaneous emission $\Gamma$. So the wavefunction would be $\mid \Psi\rangle = ...
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2answers
69 views

Can a beam splitter distinguish between more than two polarizations?

The following is based on a very basic understanding of lasers, that may be approximate or altogether completely erroneous. Given a (single-mode) laser beam, a beam-splitting polarizer ...
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2answers
54 views

Can a laser beam be captured in prism?

is there a way to shoot a laser at a prism (or something) and have it glow when the laser hits it? I want to make a small box with a small hole in it. With the prism in the box, when the laser is ...
117
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2answers
9k views

Why does a mirror split my laser beam?

Last night my daughter was asking why a mirror "always does that" (referring to reflecting a spot of light). To help her figure it out, I grabbed my green laser pointer so she could see the light ...
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2answers
205 views

How to determine the strength of a laser beam needed to cut through a specific material?

How can it be determined how strong a laser beam needs to be in order to cut through specific material? For example, if I have a 5mm thick piece of brown cardboard, is there a way to determine how ...
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0answers
46 views

Introductory books or good review paper on Free Electron Lasers

I am looking for a beginners' book on Free Electron Lasers, particularly regarding the principles of the mechanism rather than the details of the implementation. I am particularly interested on the ...
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1answer
72 views

Can a high-watt laser's scattering light be damaging to the eyes? [closed]

Heyo, I recently purchased a S3 Arctic Class IV laser pointer. I bought the 3500mW. (In case that page expires, it's 445nm wavelength, 1.5mRad variant, NOHD is 279m, beam distance at 0.25 Lux 72km.) ...
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1answer
59 views

What's the difference between stimulated and spontaneous emission in lasers and diodes?

I know that an LED emits light by spontaneous emission. To get more coherent and Monochromatic light, we should use a laser. What is the reason that laser light is the most coherent and ...
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1answer
41 views

“Classical” Coherence

I'm having a couple of courses where the concept of coherence is quite important. I know the traditional definition of coherence and it's connection to the phase of a wave. But often, I found, that ...
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0answers
72 views

Laser shone at liquid jet

When a liquid jet of water falls in laminar flow, it hits a surface. If this contact point, between the surface and the jet, is illuminated by a laser. Rings of light can be seen forming around the ...
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2answers
30 views

Stimulated emission process in lasers, Is the atom making transition a correct statement?

I was studying the Lasers, there is a section on absorption and the author is giving the statement as "An atom in lower energy state E1 may absorb the incident photon and may be excited to E2 . This ...
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2answers
6k views

Is it really possible to break the speed of light by flicking your wrist with a laser pointer?

Minutephysics has a popular YouTube video called "How to break the speed of light". In the video it states that if you flick your wrist while pointing a laser that reaches the moon, that the spot of ...
2
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1answer
56 views

LASERS: How do we get all the emitted photons of equal wavelength & equal phase? [duplicate]

As far as the working of lasers is concerned, I was convinced till the part that the light flashes on a ruby stone and the electrons are excited and then again go back to their ground state and then ...
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2answers
86 views

how to find a laser beam

Let's say that you want to know if there is a laser beam around a big area, like a stadium. Or an airport. How could you detect and find a such laser beam (could be by a laser pointer or something ...
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1answer
37 views

Compare how much a coherent laser visible green light beam spreads out with a incoherent green light beam.

Suppose I am mathematically modeling a visible green laser pointer beam which starts from the ground and ends up a half mile or full mile in the sky, projected upon an aircraft window 2 inches thick. ...
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4answers
208 views

Shining a laser onto a mirror

Theoretically, if I shined a laser at a mirror at an angle of 0 degrees so that the light was perfectly reflected back to the light source, then I should not be able to see the light because it is not ...
2
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1answer
66 views

Is there any issue/concern for a slight wavelength shift of the laser light in the LIGO experiments? [duplicate]

A friend and I were having a discussion about the LIGO experiments and were wondering if there is any issue with the laser light undergoing a wavelength shift as a result of the gravitational wave? ...
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1answer
131 views

Simple derivation of the doppler limit and recoil limit

Im doing an essay on laser cooling, and I've got two questions about the derivation of the two limits. Firstly, in the derivation of the Doppler limit, it is stated in many places that the scattering ...
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2answers
137 views

How to represent a laser pulse in quantum optics

Every quantum optics textbook that I've found says something like "a coherent state represents the output of a laser", but a coherent state is a static thing (aside from the oscillating phase of the ...
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1answer
58 views

Will I see the light?

There is a perfectly smooth wall. We have a slit parallel to it. Through that a laser beam passes. As the slit is parallel to wall the laser beam will hit it normally. So now if I see obliquely I ...
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0answers
80 views

DIY optical band pass filter or another alternative

I need to detect laser using a solar cell which would need me to either detect the laser wavelength or use pulse modulation and detect the frequency so I'm kinda here to ask if it's possible to simply ...
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0answers
30 views

optoelectronics-smallest wavelength of light

Sorry this maybe a stupid question , but i need to know: A few minutes ago i have read an article about optoelectronics: worlds first optical single atom switch The writer of the article ...
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3answers
3k views

How would a laser gun actually work?

So, let's assume that the "laser gun / phaser / beam weapon" from all sorts of Sci Fi were an actual thing. You know - a weapon that uses a laser to kill somebody. I'm trying to imagine the physics ...
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2answers
200 views

Calculate required power output for a laser

How to calculate power rating required for a laser in order to produce a dot at a specific distance after reflection? For example, the laser is 10cm from the mirror, at an angel of 30 degrees it ...
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2answers
173 views

Why does a laser beam stay collimated?

I am looking for a simple way of explaining the collimation of a laser beam. The typical discussion of the two slit experiment of quantum theory relies heavily on the Huygens principle. Its ...