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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36 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
12 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 ...
2
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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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1answer
37 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
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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13 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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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 ...
2
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2answers
231 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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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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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 ...
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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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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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1answer
44 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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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
24 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
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
135 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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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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2answers
107 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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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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20 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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25 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 ...
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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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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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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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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
47 views

Interference or something beyond?

I have an experiment with He-Ne laser in my practical syllabus. In curiosity I took a photo of the incoming radiation directly from the laser with my mobile camera. Some strange pattern is observed. ...
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24 views

Zero group refractive index within laser cavity

I am considering a uniform plane wave propagating within a laser cavity with $$ \frac{2\omega n L}{c} = 2m\pi $$ where $\omega$ is the angular frequency, $n$ is the effective refractive index of the ...
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1answer
45 views

Sech laser pulse time-bandwidth product calculation

Find the time bandwidth product for a $\operatorname{sech}$ shaped pulse. Attempt: I know that the time bandwidth product $\Delta t \Delta \omega$ for a $\operatorname{sech}$ shaped pulse must be $...
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0answers
21 views

How to estimate the heat generation and the power per square cm provided the resistance and the current of a laser diode?

Laser Diodes are very tiny. So, it is making me confused in its calculation. In laboratory, the resistance of a laser diode is 10-15 ohm and the current is 80-100 mA. How could I estimate the heat ...
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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1answer
42 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. ...
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0answers
23 views

Interesting question regarding stimulated emission

why is outgoing photon emitted during stimulated emission in phase with the incoming photon? I can't see why this is so because the two photons may be out of phase yet conserving momentum and energy.
3
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1answer
24 views

Orbital Velocity & LLR

As I understand it, light that is emitted from a source is not imparted with the motion of the source and so always follows a "straight line". If this is correct, I am having a difficult time ...
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1answer
50 views

What is the divergence of a beam from the output of a laser?

Diffraction through an aperture gives a half-angle divergence of $1.22\lambda/a$ where a is the aperture diameter. The half-angle divergence of a Gaussian beam is $\lambda/\pi w_0$ where $w_0$ is the $...
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0answers
48 views

Spinning black hole laser?

Is a laser that uses a rotating black hole's ergosphere as the gain medium possible? The idea is that the coherent light feeds off of the black hole's rotation. Assume that the black hole is ...
1
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1answer
21 views

How is it guaranteed that electrical connections could be made without destroying a diode laser?

A diode laser is a tiny diode and requires a microscope to see it. Since a laser generates a good amount of heat, the diode should be destroyed with the produced heat. But it does not happen. but why ...
4
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4answers
121 views

Intensity fluctuations at the output of a single mode fiber coupled to a He Ne laser

I have coupled a Thorlabs HNL050L-EC - HeNe, 632.8 nm, 5 mW, Polarized Laser to a 2 meter long single mode fiber patch chord using a Thorlabs F230-FC-B aspheric lens. While I am certainly able to ...
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1answer
47 views

stimulated emission in lasers [closed]

In LASERS, when the initial stimulated photon gets emitted, it stimulates other photons to get emitted. Now my question is: Does the wave of this photon interfere with other waves and makes a bigger ...
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1answer
40 views

What kind of other light sources can disturb the detection of LASER [closed]

My project objective is to detect different lasers , for example Laser Range Finder: pulse width 10ns and repetition rate is ...
4
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2answers
412 views

Is gravity the current limitation to laser cooling?

This is something I've been wondering for a while. I've read about the experiment with NASA to reach unprecedented cold temperatures in space because of the microgravity environment not being such a ...
4
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3answers
146 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 ...
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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 ...