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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11 views

Experiment using a laser beam

I need to come up with an experiment to conduct for my physics class. So far, I'm stuck at the use of lasers. What plausible experiments can be done using lasers that haven't been done before, and ...
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1answer
16 views

Clear explanation of the difference between a laser's frequency stability and its coherence length

A red laser with a wavelength of 600nm would have a frequency of 5E14 Hz. If it had a frequency spread (noise or finite cavity Q) of 6 MHz, we'd say it has a coherence length of 50 meters. You could ...
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1answer
46 views

Photons inside laser cavity

In a laser, the pumping mechanism excites an electron to a metastable state. This electron remains in the metastable state for a longer time and is de-excited to the ground state by emitting photons (...
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6answers
29k 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
544 views

How does optical phase modulation produce photons with different frequencies?

The classical description of electro-optic modulators is an index of refraction that depends on the applied voltage. For example, for a sine modulation $\sin(\Omega t)$, a monochromatic laser of ...
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1answer
39 views

Calculation of temperature distribution in bulk glass due to laser heating

I'm trying to figure out how to simplify the problem where laser pulses are focused to a small spot in bulk glass. The waist of the beam is about 20 microns. At the wavelength used there is only two-...
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1answer
18 views

Jones formalism for calculating quarter waveplate angle for circular polarized light

I am planning to change the polarization of a vertically linear polarized laser to circular polarized light with the help of a quarter waveplate. I know the final result: I have to rotate the fast ...
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0answers
13 views

Supercontinoum lasers

In my work I've encountered the phrase "supercontinuoum (CW) laser" quite a bit. After reading the wikipedia page, I'm interested in a more theoretical introductory. I'm mostly interested in ...
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1answer
19 views

does anodizing aluminum change its reflectivity at 532nm

Does anodizing aluminum change its reflectivity at 532nm? I have tested percent reflection of highly polished aluminum at 532nm. I am concerned that the aluminum will oxidize and change reflection ...
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1answer
27 views

Curvature of a laser beam with M2 parameter greater than 1

Usually a laser beam is characterized with parameter $M^2$ which shows how much does the beam size diverge in comparison to the Gaussian beam. $w=w_0\sqrt{1+M^2(\frac{z-z_0}{z_R})^2}$ But what in ...
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2answers
484 views

Free Electron Lasers (FEL) and limits on laser wavelength

Free Electron Lasers are based on Synchroton coherent radiation when a collimated electron beam suffers trajectory curvature due to a strong bouncing magnetic field inside an undulator. Free Electron ...
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1answer
38 views

Einstein coefficients for emission/absorption and energy density

When dealing with a system of two energy levels $E_1$ and $E_2$ in laser theory, the following rate equations are written: $$\frac{d N_1}{dt} = A_{21}N_2 - B_{12} \rho ( \nu ) N_1 + B_{21} \rho ( \nu ...
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1answer
126 views

Stimulated emission in LASER

I have been reading about how lasers function : A photon is used for stimulated emission of electrons from the metastable state to a lower energy state. What I don't understand is : How can "giving" ...
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3answers
107 views

White Laser Light

I have heard that recently researchers have developed white laser light by combining semiconductor laser sources of different colors. However, I have heard that before these lasers become a practical ...
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1answer
30 views

Ti:Sapphire fiber laser

Why still there is no commercial Ti:Sapphire fiber laser? And basically I didn't find information about any fiber laser at transition metals? What is the main problem here?
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0answers
14 views

Question about acummulation of nonlinear phase of laser pulse propagating in matter?

The nonlinear phase or B-integral depends on the peak power $P_p$ and $n_2$. Is it the same for 1Hz laser and for 100MHz assuming they have same pulse energy ? $P_p=E_{pulse}/\tau/Area$ $B = 2\pi/\...
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0answers
49 views

Can particles other than photons be used to make laser beams in free space?

Laser beam like things for particles other than photons would be interesting. Laser beams work because photons are bosons, massless and don't interact with each other (unless you reach the Schwinger ...
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1answer
25 views

Role of fibre components in optical schemes [closed]

Where can I find a sense of use of concrete fibre optical items in any optical scheme? For example, what does a multiplexer do in any scheme? And what does a optical add-drop multiplexer do in any ...
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2answers
85 views

Is the Pauli exclusion principle also involved in free electrons?

Imagine I want to make a laser of electrons like a laser of light. Is that possible, or does the Pauli exclusion principle prohibit that?
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2answers
237 views

If you combine multiple laser diodes, will it strengthen the effect?

I found this video (How to Make a Burning Laser Hack ), and it seems to be interesting. I'm curious: If you combine multiple laser diodes, will it strengthen it's effect? For example, if you have ...
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0answers
32 views

Femtosecond-Camera Update

Hopefully I've posted in the correct page. Honestly, I wasn't really sure where to post... Around 2012 or so, Ramesh Raskar gave a TED talk about a femtosecond-camera produced at MIT. It has a good ...
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1answer
33 views

Laser speckle reduction for integration time of microseconds

How to reduce laser speckle noise for an imaging system that demands integration times of microseconds? I am aware of these two commercial solutions: Optotune laser speckle reducer. It has a ...
85
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2answers
4k views

Why is a laserpointer able to “erase” a glow-in-the-dark sticker?

a while ago I tried to charge a glow-in-the-dark sticker using a simple red laser pointer. It was a large sticker, of the type used to mark emergency exits and fire extinguishers here in Germany. I ...
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5answers
2k views

Do free-electron lasers actually lase?

Free-electron lasers are devices which use the motion of highly energetic electron beams to produce bright, coherent radiation in the x-ray regime. More specifically, they start with a high-energy ...
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0answers
23 views

Clarification regarding atmospheric opacity

I have taken a look at the related questions Can someone explain to me the concept of atmosphere opacity? and Why can spacecraft observe terrestrial gamma rays, but terrestrial observers not ...
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1answer
36 views

Laser as an optical oscillator

How can Laser can be compared to a positive feedback amplifier? Does the two conditions for oscillator holds good for lasers too.
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1answer
45 views

How are iris diaphragms used in laser alignment?

I've read in many places that one of the canonical uses of iris diaphragms is to align a laser beam, but I'm having trouble understanding how this works, since I can always setup a set of arbitrarily ...
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3answers
56 views

Is the light emitted by a laser a 'beam' or a 'ray'? [closed]

In English, the light generated by a laser is almost always referred to in technical texts as a 'laser beam'. However, in French, Spanish, Portuguese and Italian, forms that correspond to laser beam ...
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2answers
38 views

Need for pulsed laser [closed]

Pulsed laser emit light in non continuous mode.How this makes it superior to cw laser? Why there is need in reducing the time-lag between the pluses of pulsed laser.
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1answer
25 views

Pound-Drever-Hall frequency stabilisation technique

I am having some difficulty understanding the Pound-Drever-Hall frequency stabilisation technique, when locking a laser to a stable cavity. As far as I understand: We emit the laser frequency, f0....
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0answers
35 views

What properties would a laser need to have in order to be visible in plain air?

We all know what happens if you use a laser pointer in foggy/dusty conditions: you can clearly see the line from the source to the destination. However, in plain air it is not. My question is, what ...
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2answers
7k 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 ...
5
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2answers
147 views

what happened finally to the photons emitted by the atoms cooled in laser cooling process?

I mean, do these emitted photons go out of the system without any other happening. Because they are in higher frequency and so more energy, can they be used as a source of energy?
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1answer
136 views

Quarter-wave stacks and rejection filters to protect flight crews' vision from visible laser pointers [closed]

I would like to know how the physics(and possibly mathematics) for how quarter-wave stacks could be utilized to make an ideal rejection filter that rejects all visible coherent green or blue or red ...
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4answers
4k views

Three polarizers, 45° apart

If light is passed through two polarizing filters before arriving at a target, and both of the filters are oriented at 90° to each other, then no light will be received at the target. If a third ...
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3answers
4k views

Would a laser with four possible energy levels be better than three?

I'm wondering about achieving population inversion for a laser. I learned that without an active medium, it's not possible to create a laser with only two energy levels, but it would be possible with ...
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2answers
108 views

Laser slow motion

Something really strange happen and I was hoping someone could shine some light on this. I always play around levelers with red lasers. I decided one day to shine a laser through a magnifying glass (...
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1answer
47 views

Birefringent filter, optical path length difference?

In 'The Light Fantastic' by Kenyon, I.R. (p424), it is said that for a birefringent material inclined at Brewster's angle and who's optical axis lies in the plane of the plate, we have an optical path ...
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0answers
21 views

How is a frequency comb used to stabilize other lasers?

So I am currently in the process of writing my bachelors thesis which partly concerns frequency combs. I have read that some of the applications is: Optical measuring tool. (by detecting beat-note) ...
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0answers
23 views

Laser light in a digital display

At my job, I am working with an augmented reality headset and various pairs of laser goggles. The display on the AR headset sits outside of the laser goggles. I've noticed that you can (more or less, ...
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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-\...
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0answers
26 views

How do laser triangulation sensor reflection obeys law of reflection?

I find it hard to understand how laser triangulation sensor work considering this image The laser beam form the angle of $90^o$ with the surface so how can the reflection beam form the different ...
5
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2answers
83 views

7 W medical laser without any precautions?

Today I got some medical laser treatment to treat some tendon irritation. The doctor used a red or IR laser with 7 W of power. He casually applied the laser onto the knee and was panning over the area....
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2answers
194 views

How does one calculate the minimum spectral linewidth in cm$^{-1}$ of a pulsed laser with pulse duration of 10 fs?

I calculated the minimum spectral linewidth given here using the uncertainty principle that $\Delta E\,\Delta t =h/2\pi$. Will this be correct?
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5answers
6k views

How do laser “tape measures” work?

There is a device available for about $\$40$, which fits in the palm of the hand, runs on two AA batteries, and can measure distances up to $50\,{\rm ft}$ to an accuracy of $\sim \frac{1}{8}''$ ($\sim ...
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1answer
30 views

Near perfect reflectors and LASERs

What would happen in a hypothetical scenario in which a LASER strikes a near perfect reflector (like the ones made by Jason Valentine at Vanderbilt, which reflect 99.7% of visible infrared light). I ...
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2answers
55 views

Creating nanosecond pulses from a CW laser source

Experimental setup question. If anyone aware of a technique to create pulses of several nanoseconds at a around 10Hz repetition rate from a CW laser source?
5
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1answer
55 views

Laser resonator analytic formula for sum of modes

For a sum of N modes in a resonator with identical phases, find an analytic formula for the pulse shape in the limit of many modes. Use the analytic expression for the sum of a geometric series. ...
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0answers
22 views

How is the conversion from an operator equation to a c-number stocastic differential equation justified?

In many papers on laser dynamics theory, quantum Langevin equation of operators is converted to c-number stocastic differential equations, which is analyzed to obtain results. However, why this ...
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1answer
43 views

Laser resonator modes

For a resonator, plot the intensity as a function of time for (i) when the modes have identical phases, and (ii) when the modes have random phases. Attempt Here is the equation for intensity (p. ...