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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4
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3answers
155 views

Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?

Why does a laser pointer contain a laser diode, and not just an LED? A laser pointer contains a laser diode, which essentially shines coherent light over a large angle, and a collimating lens, to ...
0
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2answers
32 views

Reason behind heating the substrate in Pulsed Laser Deposition

Why do we need to supply a constant heat to the substrate while depositing thin films in Pulsed Laser Deposition technique?
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0answers
13 views

Parameters for modelling 4 level 2 electron gain medium for laser

I have an EM simulator that can model laser gain medium by a 4 level 2 electron system. However the model requires pumping wavelength, lasing wavelength, pumping linewidth, lasing linewidth, decay ...
3
votes
1answer
57 views

How is a result of no time variation in the gravitational constant $G$ related to a measurement of no local expansion?

In this answer @PhillS linked to the paper Progress in Lunar Laser Ranging Tests of Relativistic Gravity which has given me a great start. While its main focus is on the Equivalence Principle (EP) ...
0
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3answers
126 views

Create a laser from sun light

I have read on wikipedia the basic theory behind laser. A photon passes through an excited electron which then produces the exact same photon. Light is bounced off mirrors to create more photons. Is ...
0
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1answer
27 views

Is possible to excite semiconductor with attosecond laser pulse [closed]

Is possible to excite semiconductor with attosecond laser pulse for generation THz wave?
-1
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1answer
53 views

What is the theoretical maximum data transmission rate of an optical laser at 400nm and at 800nm, with optimal pulse width? [closed]

I want to know what the highest possible data transfer is for visible light with regards to the frequency, disregarding noise. Using the shannon-hartley formula wasn't of much use, as it operates ...
2
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2answers
31 views

How do I find uncertainties in an intensity plot created from a photograph?

I have a photo of a laser beam (taken by sending the laser into a CCD). I then took the image and ran it through an image reader that gave an intensity surface plot. I then took a single cut from that ...
0
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1answer
40 views

Focal Length Calculation [closed]

Although I research in the internet, I couldn't find detailed answer. I have a question and I want to make sure from the answer. The ligth is coming from a fiber laser source and focused on a ...
3
votes
1answer
37 views

Master equation approach only suitable for good cavity laser?

As I understand, master equation and quantum Langevin equation are equivalent formalisms. However, in a Review of Modern Physics article titled sub-Poissonian processes in quantum optics, the author ...
0
votes
1answer
66 views

How can a Satellite's position/orbit be calculated using only range measurements from ground stations?

This task is often done in a process known as Satellite Laser Ranging (SLR). SLR stations (of known coordinates) track satellites, recording range measurements to the satellite at known times. I would ...
0
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0answers
18 views

What is the Reach distance of a laser beam? [duplicate]

How far can an uninterrupted beam of laser travel? And on what factors does it depend on?
1
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2answers
33 views

Projects to undertake Using Lasers [closed]

I need an economically feasible physics project that would use lasers in any manner preferably with respect to optics for a school projects class XII . Any suggestions are welcome no matter how crazy ...
9
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0answers
112 views

Stimulated Emission in QED

The explanations of stimulated emission which I have found all describe the phenomenon in terms of non-relativistic quantum mechanics. How might you describe it in a field theory such as QED? In ...
0
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1answer
31 views

What medium could I use for a laser pointer to hit and illuminate an entire area behind it?

I'm in the planning stages of making a fun project for my nephew which will allow a wood gun with a laser pointer attached to 'shoot' at a target area. The target area will most likely be a piece of ...
0
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0answers
26 views

why atoms can't be directly excited to meta stable state? [duplicate]

IN LASERS,Why is it necessary to excite atoms at higher energy level than meta stable state, why can't we just excite it to meta stable state and obtain the condition of population inversion. Don't ...
1
vote
1answer
55 views

Why does generating EUV frequency combs require femtosecond enhanced cavities?

When generating extreme UV (EUV) frequency combs using high-order harmonic generation, why does the harmonic generation step need to be inside a femtosecond enhanced cavity for the comb to work? More ...
5
votes
1answer
68 views

How to find Intensity from field of train of pulses?

Lets say there is process that emits a field $E$ every half cycle of a driving laser pulse (in particular, high harmonic generation). The total field is $$ E_{tot}(t) = \cdots + E(t-2\pi/\omega)-E(t-\...
5
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2answers
123 views

Laser mode locking

I don't understand why we need to do mode locking in laser to generate short impulse ? Indeed, If I see this picture from wikipedia : By using multiple frequencies and the limit conditions of my ...
3
votes
2answers
59 views

Optics to correct focal distance across a plane

I have a laser beam which is focused to a point at a certain distance. I'm then going to use a galvanometer to scan that beam across a plane. Obviously, as the beam scans across the plane, the ...
20
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4answers
7k views

Can lasers lift objects?

I have been fascinated by a very intriguing question - Can lasers push objects up? I have done the below math to find out Lets say we have a $1000~\text{mW}$ laser and we would like to lift an ...
0
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0answers
42 views

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 CCD....
1
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1answer
101 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 ...
1
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0answers
30 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?
0
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1answer
36 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 ...
0
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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 $\...
1
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1answer
29 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 ...
0
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0answers
34 views

How would a BEC respond to the gravitional force of a small mass so sensitively?

Recently I watched a BBC programme on anti-gravity, most of which was wishful thinking by NASA and BAe Systems 20 years ago. At the end of the program through, they did show what appeared to be a ...
4
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1answer
75 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 ...
0
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2answers
489 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 ...
0
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0answers
23 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 ...
1
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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 U(z,\...
0
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0answers
28 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 ...
1
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1answer
28 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 ...
1
vote
1answer
60 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 ...
0
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0answers
31 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 ...
0
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1answer
35 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 ...
1
vote
1answer
59 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 ...
0
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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
2
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0answers
89 views

Non-semiconductor CW laser types for 445-465nm

Am I missing something in this list of non-semiconductor CW laser types to get emission in the range of 445-465nm? Are there any crystals directly emitting in this range with UV pump? Currently I am ...
1
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1answer
35 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?
0
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1answer
59 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 ...
0
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0answers
46 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 = ...
2
votes
2answers
73 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 ...
0
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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 ...
120
votes
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 ...
0
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1answer
99 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 ...
-1
votes
1answer
81 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.) ...
0
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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 ...
0
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1answer
42 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 ...