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.

learn more… | top users | synonyms (1)

2
votes
0answers
56 views

List of laser-cooled atoms and ions

I'm familiar with the requirements for an atom or ion to be cool-able with laser cooling -- a closed transition -- or close enough that the leaks can be plugged with repumpers. But is there a list of ...
2
votes
0answers
82 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 ...
2
votes
0answers
57 views

Determine laser cavity modal content from beating / interference?

I'm trying to better understand the modal content and dynamics of laser cavities. I'm specifically interested in mode-locking, although this question is pretty general and applies to CW lasers too. I ...
2
votes
0answers
146 views

Laser divergence/convergence over large distance

I have hit a roadblock in my simulation, where there are 2 authors with contradicting equations on the model. So I have simulated both, and drew it out for a few diameters. My dish size is 40m. I am ...
2
votes
0answers
147 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 ...
2
votes
0answers
93 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 ...
2
votes
0answers
314 views

Levitation rotation speed involving laser acceleration, pyrolytic graphite and a vacuum

The experment would involve a small NIB magnet levitating between or on the diamagnetic material pyrolytic graphite, unlike other forms of levitation this doesn't require power to run such as ...
2
votes
0answers
228 views

How is the “negative dispersion” derived?

I'm looking at Kopfermann H., Ladenburg R., Nature, 122, 338-339 (1928) and it appears Ladenburg in Ladenburg R., Z.Physik, 4, 451-468 (1921) was the first to discover the phenomenon of "negative ...
2
votes
0answers
387 views

Maxwell's Demon - laser cooling

There’s an interesting article on Scientific American that tells how to cool individual atoms to within a very tiny fraction of Absolute Zero. It uses two laser beams acting on a very cold rarified ...
2
votes
1answer
148 views

Consistently oscillating micron sized particles in a liquid

I have an idea that would involve the measurement of an oscillating substance whilst the substance is immersed in a liquid. However, the method that I would use to measure the frequency of these ...
1
vote
10answers
723 views

How far can light go?

When a ray of light is projected, (say) from the surface of Earth to outside in space. The condition is that, there is no obstruction to it till infinity (it travels only in vaccum). My question is ...
1
vote
3answers
621 views

Average of $\sin^2 \omega t$, $\cos^2 \omega t$ for long times

I don't understand how the averages mentioned in excerpt below work out. The question is regarding calculating the power spectrum of an oscillating classical dipole. IS averaging over long periods, ...
1
vote
3answers
207 views

Can one build a laser using spontaneous emission?

We use stimulated emission and not spontaneous emission to produce lasers. Why is this? Can't we produce lasers by the spontaneous emission method?
1
vote
3answers
127 views

Is the output of a laser pointer polarized or not?

How to verify it? Is a laser necessarily polarized? I have a laser pointer with wavelength 532nm in hand.
1
vote
2answers
1k 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 ...
1
vote
2answers
3k 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 ...
1
vote
3answers
361 views

What limits laser pulse duration to single cycle?

Why pulses shorter than single cycle cannot propagate in free space ? Is there fundamental reason or it is engineering ? Is it possible for a laser pulse to have bandwidth that can support half cycle ...
1
vote
2answers
82 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).
1
vote
4answers
2k views

How can a laser pointer have range of several kilometers in atmosphere?

Laser pointers manufacturers claim that some pointers have range of several kilometers. Okay, they use a powerful laser, but that powerful laser usually has power less than one watt. Okay, the laser ...
1
vote
4answers
267 views

How to measure the size of a laser dot?

I'm not a physicist, that's why I'm asking you if there is maybe an easy way (e.g. a mathematical law) to measure the size of a laser dot, or its diameter. The setup It contains a laser, a high ...
1
vote
3answers
202 views

Calculate the rise in temperature from directed radiation [closed]

For example I have a 1 watt laser and direct it to a sheet of metal (copper), if I were to direct it for say a time interval of 1 minute what would be the change in temperature? I can predict that it ...
1
vote
3answers
149 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 ...
1
vote
2answers
82 views

Ultrafast Lasers

Is the main idea of femtosecond or attosecond lasers is to achieve the high energy or do we have any other parameters achieved by ultra-fast lasers ?
1
vote
1answer
50 views

What could cause a diode laser to be emitting the half-harmonic of the fundamental frequency?

I have a 405nm laser which is seemingly outputting a small portion of 810nm light. I am wondering what mechanism this could be caused by. Is this a down-conversion phenomenon or perhaps just another ...
1
vote
1answer
118 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 ...
1
vote
1answer
82 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, ...
1
vote
1answer
1k views

Heating metal with laser? [closed]

Can a laser be used to heat metal's to the point they glow red? How are laser cutters able to cut metal very easily? How much heat can a laser generate?
1
vote
1answer
61 views

How can net output of photons in laser occur?

The way I see it, in both spontaneous and stimulated emission, one atom being de-excited would result in one photon being produced. So if we excite $10^{23}$ atoms, only $10^{23}$ photons would be ...
1
vote
1answer
157 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 ...
1
vote
1answer
74 views

Why do we see brown light?

While researching about lasers (it's my hobby), it suddenly hit me: there are lasers for every color of the visible spectrum, but there are no brown lasers. Brown isn't even on the rainbow. How is it ...
1
vote
1answer
22 views

Optical pumping without stimulated emission

If I want to pump Rubidium 87 atoms From fg = 2 to fe=1 level with a laser tuned to D1 transition and avoid stimulated emission then it is sufficient that I use a laser power which gives me an ...
1
vote
1answer
60 views

does photon travels in a helical path in an optical vortex?

The wave front of the optical vortex beam is helical. Does it mean that the photon travels in a helical path? When the optical vortex beam is focused on a screen, an annular ring with dark center is ...
1
vote
2answers
63 views

Why lasers and not light? [closed]

Some laser applications consist simply concentrating light into a small spot (e.g., image projection, welding, cutting, etc.). Why are lasers used instead of a simpler light source?
1
vote
2answers
91 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?
1
vote
2answers
131 views

Convert normal white light to laser-like light?

Is there a probable device that can convert white light to laser-like light without the need of an electrical stage in-between? I'm thinking of something along this level. A very precise filter and ...
1
vote
2answers
103 views

Why does light from a laser end up in a concentrated spot?

I've heard from several people that photons will always take the past of least action while travelling, so why does laser light projected on a surface appear concentrated to a single spot when ...
1
vote
1answer
98 views

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 ...
1
vote
3answers
125 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 ...
1
vote
2answers
236 views

Do acousto-optic modulators shift the frequency of the diffracted beams?

Today I read an introduction on an optical device called an acousto-optic modulator, which is used in many optical experiments. It is the first time I have heard of this element. The material showed ...
1
vote
2answers
150 views

Max temperature that can be obtained from radiation source when nonlinear interaction with matter is important?

Using a black body radiation as furnace it is usually said that the max achievable $T$ is limited to the T of the source. So a source of 3000K can not be used to heat a body above 3000K. A long ...
1
vote
1answer
327 views

Derivation for 7.14 in Atomic Physics by Foot

I was going thru Ch7 of Foot and trying to fill in the gaps. However I got stuck on (7.14). So Foot was working with a two level system with a small perturbation in the Hamiltonian resulted from an ...
1
vote
1answer
59 views

Limits of laser spectroscopy for determining size of a molecule or particle

Say you have a number of particles respectively molecules suspended in air. The diameter of the particles $d_{particle}$ are of the order 1 to 100nm. Can you actually, i.e. in practice, measure the ...
1
vote
2answers
1k 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 ...
1
vote
1answer
213 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
30 views

Gaussian beam shape

In this diagram of a Gaussian beam, why does the radius vary with z position? Is it assumed that a Gaussian beam is always being focus by a lense? Why can the beam not go any smaller than $w_0$ and ...
1
vote
1answer
55 views

Power of several focused laser beams on a small surface

After viewing this: My Homemade 40W Laser Shotgun Will the initial 40W power of the diodes beams be roughly transferred to the targeted surface where the 8 beams are focused, or will there be a power ...
1
vote
2answers
463 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 ...
1
vote
1answer
48 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 ...
1
vote
2answers
182 views

Laser power consumption vs power output

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?
1
vote
1answer
51 views

How to choose laser goggles for low-power laser of specific wavelength

I need to choose laser goggles to shield eyes against 678 (+/-8) nanometer laser (5mW power). The laser has a red beam. I found for example some goggles that are sold for 650nm, with a blue lens. ...