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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60 views

Can a laser work forever if constant electricity is provided?

Can a laser work forever if constant electricity is provided? If we take a laser and provide it with constant electricity will the reactions in the semiconductor generate photons forever?
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0answers
24 views

Would an inverted design of a laser phosphor display (LPD) work?

Background info... It is my understanding that a laser phosphor display works by emitting RGB laser beams through a mechanism that cycles them in a pattern similar to a cathode ray tube. When I read ...
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48 views

How do I model this Quantum Cascade Laser (QCL) using COMSOL? [on hold]

I'm trying to model this: GaAs on-top of a heat-sink made of Copper. It's trying to simulate a type of Quantum Cascade Laser, I'm looking at the effect the temperature has by running a 10V voltage ...
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0answers
35 views

Optical fibers: pulse spreading in an optical fiber due to material dispersion [closed]

I am a newbie to the world of lasers and optical fibers and was working my way through some basic problems, when I encountered this one: Calculate the pulse spreading in an optical fiber due to ...
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0answers
21 views

How much energy does a PV cell need to work?

How much energy does a $1m^2$ photovolatic/solar cell need to work? Can it work using a bunch of Laser lights? Edit: Ok so this PV cell is $1m^2$ is dimesions. The N-type has silicon doped with ...
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0answers
21 views

What is the “Obscuration Factor (OBF)”?

In a paper I am reading for my master thesis I came across this "obscuration factor (OBF)". The authors indicate that it is a measurement of the average intensity of reflection. They do not give a ...
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1answer
161 views

Does my green laser pointer emit three distinct frequencies, or is my measurement flawed?

I was playing around with a cheap diffraction grating and my set of laser pointers, and I noticed that while the red and the blue pointers produce a single point in the spectrum, my green laser ...
3
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1answer
35 views

Laser diode spectrum vs LED spectrum, why so much difference in broadness?

I've been reading about how light is produced in both laser diodes (the most common types of lasers) and LED's. The mechanism seems very similar if not exactly the same: one applies a potential ...
3
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1answer
39 views

Is it possible to directly pump a laser using sunlight?

Typically in the old days one would use a flash tube to pump a ruby crystal. Is there any way, or any lasing material, that could use concentrated sunlight directly for either continuous or pulsed ...
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0answers
24 views

Could laser speckle patterns be used in diagnosing vision defects?

At the London Science Museum some years back, I saw a device which projected a laser speckle pattern and had a sign explaining that it would appear stationary for people whose eyes were correctly ...
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3answers
610 views

What causes the specific pattern of sparkly light from a laser pointer

I have a fairly cheap green laser pointer that produces a fairly big spot of light (actually two spots most of the time!). I'd guess the size of the spot is about 1/100th of the distance from the end ...
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2answers
51 views

Laser tattoo removal

I would like to know if someone could please briefly explain how laser technology of tattoo removal works? And second, could there possibly be any dangers to cells, specially on bones?
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2answers
51 views

What laser and BBO are needed to create entangled laser streams?

I have been reading about entangled particles, lasers, the two slit experiment, etc. I really know nothing from physics (i.e. equations, formulas, theory); so please respond accordingly. From my ...
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0answers
27 views

Any suggestion of laser pointer for everyday life study of fluorescence?

I want to buy a laser pointer to study fluorescence in my kitchen. Any suggestion? What kind of laser pointer? What stuff for demonstration?
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0answers
42 views

Is it possible to efficiently extract phonons from a lattice?

The population inversion generated in lasers occurs in multi-level atomic systems. As an example, the Nd:YAG energy diagram is shown below. The pump pushes the Nd ions up to the upper levels, and ...
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0answers
22 views

Losses in a laser diode

How do I convert loss/gain from units of /cm to /s? Intuitively, I would say multiply loss in /cm with the group velocity c/n, where n is the refractive index. Am I missing anything?
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1answer
27 views

Cooling atoms using emitted photons from a laser cooled atom

In Doppler cooling procedure, is it theoretically possible to use the emitted photons from the target atom (cloud) to cool more atoms? The idea is to cool the atoms rapidly by using energy emitted by ...
5
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1answer
113 views

What causes light to travel through a curved fountain of water?

Today I observed a tilted fountain spurting water upward (the water fell smoothly; no detectable turbulence). A colored light was shown upward into the water as it left its source. This light traveled ...
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1answer
35 views

Non resonant modes in cavity

I have a simple question. Suppose we have a laser with a cavity such that the frequency of the light that the laser emits does not match with any longitudinal modes allowed by the cavity. In ...
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0answers
22 views

Carbon fibre laser beam dump material?

A few years ago I came across a material used as a high power laser beam dump. It was made from carbon fibre which looked like a mat made of high density bristles ie all the fibres on the top of the ...
3
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1answer
93 views

Michelson interferometry - is a compensator plate necessary?

I am studying the Michelson interferometer shown in figure 2 (similar design shown below) of the AMRITA vlabs tutorial. There it is stated that Since the reflecting surface of the beam splitter ...
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2answers
52 views

Coherence length interference pattern

I recently watched this video that illustrates a laser's coherence length: https://www.youtube.com/watch?v=LixwAXsN8vg I've learned in class that coherence length of a laser with several wavelengths ...
3
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2answers
67 views

Michelson interferometer interference pattern [duplicate]

My friend and I recently did an experiment on Lasers where we shot a laser beam through a Michelson interferometer and observed the interference pattern on the wall. Here is the basic setup: One ...
3
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1answer
40 views

Does chirp (GDD, TOD ) affect the temporal coherence of a laser?

Lets say we have a laser beam with finite temporal coherence. A broadband spectrum with a transform limited pulse of 100fs. If we measure its temporal coherence when the pulse is transform limited ...
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1answer
38 views

2 level atomic system interacting with Black body radiation. Relaxation time issue

I am studying the transient regime of a 2 level atomic system ($N_1,N_2$) interacting with a blackbody radiation from a source at constant temperature $T_{nr}$. The initial state of the atomic system ...
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0answers
37 views

Entangled Photon (laser pointer)

From a laser pointer emission; is it creating entangled pairs of photon? is it possible to get more than "pair" entangled, like group of photons all entangled?
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32 views

Laser travelling through a radially graded index of refraction

A laser beam propagates through a region whose refractive index varies as $\mu=\mu_0(\frac{r}{r_0})$. At a distance of R the beam makes an angle of 30° with the normal. Find the minimum seperation ...
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1answer
22 views

Laser cutting - ignition

How is that sometimes laser cutting by burning material or "flame cutting" causes ignition of the whole material like here where the whole paper starts to burn and sometimes doesn't allowing precise ...
2
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1answer
61 views

How does a laser emit light in a coherent state?

Lasers work by stimulated emission of atomic transitions. Stimulated emission produces two photons which, because the particle number is well-defined, projects the field into a Fock state. However, it ...
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2answers
236 views

Why does a circle of light appear when I shine a laser pointer at a wire? [duplicate]

When I point a laser at a wire , a circle of light appears on a wall behind it . why this happens. What is the circle of light and why does it appear? Could anyone give some tips on what I should ...
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2answers
72 views

What wavelengths to combine to get 488nm?

Is it possible to combine a blue and green lasers to get cyan? If I used 405nm and 532nm, would I get (405+532)/2= 468.5nm? Is this a correct calculation?
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1answer
58 views

Lasers : Threshold Pump Power for Laser Oscillation [closed]

I was working my way through some basic laser problems , when I cam across this one : Consider the ruby laser for which we have the following values of the various parameters: $N =$ $1.6$ x ...
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1answer
46 views

What is a lineshape function $g(\omega_0)$ in a Laser?

I am a newbie to the world of lasers and was working my way through some basic problems, when I encountered this one: Optical Electronics, A.K. Ghatak and K. Thyagarajan (Cambridge University ...
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0answers
36 views

Maximum laser power that mirror can handle?

Can I use standard mirrors used for lasers used for laser shows to build some laser that has higher power and is able to burn materials? What are power and power density limitations that cannot be ...
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0answers
45 views

Photons and gravity [duplicate]

A very powerful laser pointing to the empty space next to small object in space. The photons in the laser beam does not hit the object. Will the small object be gravitationally affected by that laser ...
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1answer
75 views

Is lasering some natural phenomenon soemwhere?

Laser is actually the simplest kind of light, from a physical point of view. Many people think it is some rocket science simply because it is not natural but takes some human efforts to create. So, ...
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1answer
46 views

Laser Cutter Power/Wavelength to Cut Paper

I've been reading up on laser cutting and it seems that 808nm at around 2 watts is typical to cut paper. How would one calculate the wavelength and power required to cut an arbitrary material?
5
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1answer
77 views

Options to correct rectangular laser beam profile?

We recently switched to a 405 nm laser diode which has a terrible beam profile -- it is a well-defined rectangle with an aspect ratio of about 10:1. The image below shows the collimated beam which ...
2
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1answer
56 views

Propulsion force on a laser pointer?

How to calculate propulsion force on a laser pointer in reaction to the emitted light power in watts? Should I just divide power by speed of light? Since power is energy per unit of time, hence ...
3
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1answer
42 views

Can you thermally pump a laser? (and problems with population inversion)

Recently a question was asked during a lecture about the possibility of thermally pumping a laser. The lecturer claimed that this is pretty impractical as typical transitions in the visible light ...
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1answer
36 views

Using attosecond laser pulses to view electrons

It is often said in popular media sources that creating shorter and shorter laser pulses will allow us to view electron dynamics as they happen in chemical reactions. This is obviously beneficial in ...
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1answer
26 views

doppler cooling temperature limit

Wikipedia shows a heating effect that causes minimum temperature achievable in doppler cooling as: "The atom performs a random walk in momentum space with steps equal to the photon momentum due to ...
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2answers
27 views

Laser beam sensed by scattering

Can a laser beam, whether it is a IR laser or of the visible to human eye spectrum, be seen/sensed by an electronic eye like a photosensor/photodetector, not human eye, if the beam is just in air? For ...
3
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1answer
75 views

How powerful would a laser need to be to make a hole in snow?

How strong would a laser beam have to be (and what frequency would be optimal) for it to be able to make a hole in snow? Here I am looking for a laser beam that could make the hole after less than 2 ...
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1answer
29 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 ?
3
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1answer
338 views

Can a UV LED cause air ionization?

I am thinking of the high power LEDs at around 250nm wavelength and an output power of some 30mW optical, in continuous mode either divergent beam or focused.
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4answers
96 views

Focusing and collimating laser light on a table top scale

I am looking for a summary of practical methods of focusing and collimating laser light, which I guess are contradictory objectives, or are they? For example, when I use typical small diode lasers, ...
2
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3answers
66 views

Laser beam photon counting

I'd like to know if devices exist that are able to detect the single photon missing out of a normal laser beam. I am aware of the fact that single photon counters do exist, but I'd like to ask some ...
2
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1answer
50 views

Short Laser pulse in near field bandwidth

Is there a way to create a short laser pulse that has, at least in the near field, a very narrow frequency range?
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2answers
428 views

How do I find the right lens for my laser?

I purchased this line laser recently and I'm running into a bit of an issue. The laser shoots out at a 120 degree angle which is perfect. However, once the laser spreads to about 4.25 inches, I need ...