Questions tagged [laser]

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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Are laser diffuse reflections really so dangerous?

Class IV lasers are lasers with an optical power higher than 500mW, and for these lasers "even diffuse reflections can cause permanent eye damage". Well, I would like to understand how this ...
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Phase shift measurement calculation problem [closed]

I hope this is the correct site for this post. I am interested in mobile robotics and now I'm learning about its sensors.I have come across a problem where I need to calculate the distance of the ...
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What lenses are generally used to focus a beam of light into a horizontal line?

I am trying to find out more about the inner workings of a laser scanner I'm using to map objects. In this case the technical details are quite hard to come by. The laser scanner generates a beam of ...
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Difference-frequency-generated (DFG) spectral width

If we have two laser beams with central wavelengths $\lambda_1$ and $\lambda_2$, (one with a spectral width of $\Delta\lambda_2$ and one with negligible spectral width), interacting in a non-linear ...
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Sources about $M^2$ parameter for lasers

I am trying to find some sources about the $M^2$ parameter for lasers, I have already looked for that in 3 of the following books: laser-electronics-prentice-hall-1995 OrazioSvelto PrinciplesOfLasers ...
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Fading law of the peak value of the E-field in a laser beam

I am not used with the theory of lasers, and feel uncomfortable with it. According to Wikipedia, the electric field of a gaussian beam can be given in phasor notation by $${\mathbf E(r,z)} = E_0 \, \...
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What happens when bending laser light in a liquid stream smaller than its wavelenght?

When you point a laser into a water stream it bends with the waterstream and exits at the end. It bounces constantly from the "virtual wall" till it reaches the end of the stream. Now if the ...
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Why do lightbulbs produce any light, when the light they produce is incoherent? [duplicate]

First let's talk about lasers. A simple three level laser produces coherent light from stimulated emission, and incoherent light from unstimulated emission. I have been told that the intensity of ...
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Could bremsstrahlung provide evidence that a Black Hole (BH) forms the underlying geometry of the electron?

There are several proposals that model electrons as BHs. For example, A. Burinskii proposes a spinning soliton on a Kerr-Newman BH geometry (enhanced to an MIT bag model in “New path to unification of ...
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Diode laser optics - How to shape the beam of a Diode bar?

I have a 40w, 808nm, CS mount diode bar. I would like to build a something similar to a Rofin Dilas laser diode. How to choose the optics, measure distance, focus the beam into a fiber coupler? I came ...
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Is it possible to create a laser pointer with adjustable beam width?

Is it possible to create a (line) laser pointer with adjustable beam width? I mean instead of having a dot laser pointer, create one where one may press a button to switch from 10m line beam to 5 m ...
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Vertical peaks in single slit diffraction pattern

I have the output from a single slit diffraction experiment using a HeNe laser (632.8nm), the diffraction grating is placed vertically so you expect to see only horizontal diffraction peaks in the “...
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Use standing wave to understand mode locked laser

Recently when I was trying to explain the principle of kerr-lens mode-locked laser, however I find that I don't even understand it myself. People around me always say the longtitude modes of the ...
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Estimate laser diode beam quality from datasheet

I want the estimate the minimum divergence angle that can be obtained when collimating the beam coming from a laser diode. For this I intent to use the following equation from https://www.rp-photonics....
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Terahertz generation in semiconductors after ultrafast laser excitation

Terahertz can be generated by means of the photo-Dember effect, where a short laser pulse generates electrons and holes. These charge carriers have a different mobility which gives rise to a dipole ...
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Astigmatism in bow tie cavity

I am a bit confused about how to account for the astigmatism in a bow tie cavity. I did the math for the resonant frequency of the tangential and sagittal direction of a Gaussian beam, and I got in my ...
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What does $\partial_{k_\mu}$ mean on the Simon Laboratory site at Stanford University? (condensed matter physics and quantum optics)

I realize this is a strange question, but I have come upon the Simon lab site a lot, and that symbol or motto of theirs is everywhere, and I am just wondering if it means anything..... http://simonlab....
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How can light have a color dependant on wavelength, but still travel the same constant speed in a vacuum?

Based on my understanding, frequency is dependent on the number of times that the wave passes through the resting point, and therefore the frequency is the speed of the wave. That makes sense to me. ...
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Why are pulsed lasers are the main tool used in nonlinear optics applications, instead of CW sources?

Why we often use pulsed lasers for nonlinear optics applications (such as SHG) instead of continuous wave lasers?
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Is their any convention for measuring cooling in a material?

Im dealing with laser heating and cooling, in this area you have a lengths that are accepted measures such as an absorption depth and Diffusion length. https://www.pveducation.org/pvcdrom/pn-...
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Is a $CO_2$ explosively pumped laser possible?

If an explosive that releases $N_2$ and $CO_2$ is detonated inside a laser cavity, will it generate laser light efficiently? I read a paper where they made a $60$W CW laser with propane and oxygen ...
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How can I collimate a laser beam of 100 wavelengths in vacuum?

Before collimating, the beam will have diverged a bit to a radius of 5cm, the range of the wavelengths is 1400-1600nm and I don't want to lose more than 30% of initial power. I'm asking in general how ...
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What wavelength should a laser beam have to not interact with the dust in the air for the laser emitter location not to be possibly detected?

What wavelength should a laser beam have to not interact with the dust in the air for the laser emitter location not to be possibly detected by any kind of wave detectors? What is the quantitative ...
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How does two-wavelength interferometry mitigate vibrations in density measurements?

I am currently using interferometry to measure the density of a plasma. The interferograms are suffering from vibrations, and I know that two-wavelength interferometry may mitigate this. I am however ...
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How to measure the wavelength of a laser? [duplicate]

I'm building an enclosure for a laser engraver that emits light at ~455nm. I want to be able to measure the wavelength of the light that is refracting off the item being engraved. I would want to be ...
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What causes a baseline to form in laser spectroscopy?

I am rather new to laser spectroscopy and recently came across some absorption spectra, produced by a MIR QCL. All of the spectra featured a prominent baseline, which can be roughly fitted by a 3rd or ...
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Extracting a mass attenuation coefficient for a dilute metallic gas for visible wavelengths

Currently, I am examining the attenuation of a visible wavelength laser with an initial intensity, $I_0$ by a metal vapor (in this case Aluminium) that has a density, $\rho_g$ of around 0.02g/cm$^3$. ...
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Narrow-bandwidth laser and its beam size on uncertainty principle

I read that a single frequency laser can have a bandwidth as low as a few kHz, but according to the uncertainty principle, $\Delta x \Delta p = \Delta x \Delta f h/c >=\hbar $, so $\Delta x \sim ...
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Temporal vs Spatial Contrast in Speckle Contrast Imaging

I have been reading about Speckle Contrast Imaging recently. Its quite an interesting topic given that it should be possible with relatively inexpensive equipment. The basic premise from what I ...
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Can the spot of a laser on a plane be extinguished by another laser?

Of course the second laser have to be stabilized with the first in frequency. The second one is fed to the spot through a variable delay line so the phase to be completely opposite. I suppose they ...
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How can any quantum superposition get produced, given conservation of energy?

Imagine I have a two-level quantum system $Q$ (motivating example: a trapped-ion qubit) where there is some energy difference between the states $\vert 0\rangle_Q$ and $\vert 1\rangle_Q$. Suppose I ...
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Is the accuracy of atomic clocks about engineering limits?

I read that a microwave with specific wavelength is shone on a bunch of atom to make them change energy state from ground to excited state, then they measure this difference in energy to determine its ...
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How to find peak power at 1550nm using an optical meter?

I have a setup of tunable laser source at 1550nm connected to a spectrometer(Can't publish the name of spectrometer). The spectrometer has a range of 1510-1595 nm. The graph shows wavelength vs ...
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How does an attenuator inside a polarization interferometer change polarization?

Suppose you have source of coherent light, a laser beam, with +45 polarization. A polarizing beam splitter (PBS) splits the beam into its horizontal and vertical components. The second polarizing beam ...
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How to implement a very precise polarizer inside a fiber-based setup?

A tricky question: I need to use polarizers with a ~5 arcmin precision inside a PM fiber-based system. What are some (hopefully cost-effective) ways of achieving this? The setup works with linear ...
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What is the beam divergence of a defocused point source collimator?

It is widely known that placing a converging lens in front of a collimated light source focuses all light into a point @ $d=F$, and that the inverse occurs: a point source at the focal length of a ...
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Why doesn't a laser emit black body radiation?

While deriving A and B coefficients we use Planck's law of blackbody radiation, but the spectrum obtained from the laser is not that of a blackbody because we get a very small band of light as output. ...
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Non-dimensionalizing laser system of diffeqs, Strogatz Nonlinear Dynamics and chaos 3.3.1 D

The system of equations in question is $$ \dot{n} = GnN - kn$$ $$\dot{N} = GnN - fN + p$$ Where ${N(t)}$ is the number of excited atoms, ${n(t)}$ is the number of photons, ${G}$ is the gain ...
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Amplifying light with fluorophores

The fluorescein fluorescence spectrum shown below shows distinct excitation and emission peaks (with some overlap). If I were to "pre-charge" a fluorescein solution with a laser at ...
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Can laser diode characteristics comparison be based on laser of one length?

As we know, e.g. from this website, to know the laser Transparency Threshold Current and Internal Quantum Efficiency, we need the LI curves from lasers of various widths. However sometimes it is ...
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Is there a way to calculate the intensity of light absorbed that passed through a solid?

So I have lab I need to do for school and I need a formula that calculates the intensity of light transmitted through a solid (in my case sheets of paper). I had a probe that measured the intensity of ...
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Are the electron and hole densities always equal in an intrinsic semiconductor?

In my laser physics book (Laser physics by Hooker and Webb) it is stated that the density of electrons injected into the intrinsic active region of a diode laser is equal to the density of holes. I am ...
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How does one get this steady-state solution?

I am studying the concept of a "gain medium" inside a laser cavity. The active atoms are taken to have the two levels $a$ and $b$, separated by energy $\hbar \omega$ and represented by a ...
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Describing intensity of electric field in laser cavity as a dimensionless quantity

I am studying the concept of a "gain medium" inside a laser cavity. The active atoms are taken to have the two levels $a$ and $b$, separated by energy $\hbar \omega$ and represented by a ...
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What is electrical efficiency of ionized air

I have tried finding the correct answer to this question with no avail. I want to know what the loss would be when a path in the air is ionized and electricity is transferred from a source(lets say ...
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Reduce subjective speckle contrast while increasing objective contrast

I have been trying to learn more about laser speckle phenomena, and I’m wondering if it’s possible to increase the contrast of objective laser speckles while decreasing subjective speckles without ...
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Can crooked surfaces alter speed messurement using a laser?

this might be an unconventional question yet I think the physics community would be the one to help here. Please hear me out. So my problem/question: I drove into a laser speed trap with my motorcycle ...
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"Loss" around the transmitting window of a laser cavity due to diffraction?

Take a laser cavity consisting of a gain medium, a totally reflecting mirror, and a partially transmitting window: (https://www.researchgate.net/figure/Laser-cavity-composed-of-a-gain-medium-in-...
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How long does it take to accelerate to 10$ms^{-1}$ using a 10W laser?

Given a laser of $P=10W$ and a space vessel of $100kg$, how long would it take to accelerate to a velocity of $10 m/s$ using the laser as propulsion? My train of thought is that by using $E=Pt$ and $...
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Fitting time resolved data with a convolution

I want to fit experimental data of a time dependent Signal. The Signal is the result of a concentration convolved with a pulse. But the question is more in general, so I hope the picture below will ...
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