Questions tagged [laser-interaction]

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35 views

How hot is a laser beam going to be when strong enough to create a plasma channel?

The type of laser I'm referring to comes from here: https://en.wikipedia.org/wiki/Electrolaser Would an extended use of it be able to burn stuff?
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23 views

What are the losses in a laser cavity?

I studied that to get the lasing conditions gain must overcome the losses. But what are the losses? Thanks a lot
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3answers
65 views

Why do lasers need mirrors at the edge of the cavity?

If the avalanche stimulated emissions start from the first absorbtion that occurs in the cavity then why are mirrors needed? I imagine a photon that even without mirrors stimulates extra coherent ...
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14 views

What is the fastest way to photodissociate/bleach melanin - with lasers or LEDs - without heat?

Melanin is the chemical that makes our skin dark. Melanin absorbs in very well in the UV, but when one does so, the solution/molecule gets very hot. Is there a way to photodissociate melanin without ...
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29 views

Does the optical transmittance of pulsed laser through a transparent material differ quantitatively from a continuous wave laser?

The absorption & transmittance of light through a transparent medium is described by the Beer-Lambert law. But the equation does not factor in the time parameter so I assume it describes ...
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49 views

Saha-Boltzmann Equation

I am following Ahmed, Ahmed, Rafiqe & Baig A comparative study of Cu–Ni Alloy using LIBS, LA-TOF, EDX, and XRF paper on Laser Induced Breakdown spectroscopy. It mentions two versions of Saha-...
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33 views

Angular momentum and Zeeman effect

Supposing an Alkali atom positioned in magnetic field in $z$-axis. I understand linearly polarized laser propagating in $z$-axis can induce $\sigma$ transmission. But I could not figure out how laser ...
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47 views

Quantum Coherence in a Two-level System in the Density Matrix Formalism

Dealing with semiclassical light-matter interaction, in particular the interaction between an electromagnetic field and a two level system using the density matrix formalism, I learned that the system ...
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46 views

Direct energy weapon vs kinetic energy

Good day, I would love to ask this question. Lets say that I have a energy source capable of delivering 10^30 watts with capacitors to match it and I would like to use this energy as a weapon (sort ...
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1answer
32 views

What angle does light leave a 400micron fibre if it entered from a single mode fibre (0.14NA)?

We would like to connect a single mode coupled laser to a 400micron fibre. Ideally, we'd like the light to come out of the 400micron fibre at all angles or close to the maximum divergence angle, ...
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1answer
30 views

What laser frequency is needed for the Doppler cooling of iron?

What laser frequency is needed for Doppler cooling iron? How do you determine this frequency?
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88 views

Where does laser reflection (1) come from?

I have the above experiment setup where a triangulation-based laser scanner projects a laser (line) towards a transparent glass material. I then took a picture using my phone (indicated in the above ...
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28 views

Optical tweezers : dipole force or radiative pressure?

Two types of forces are usually considered to describe light-matter interaction. On the one hand, the radiative pressure, which corresponds to absorption - spontaneous emission cycles, is proportional ...
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27 views

For a laser that changes color discretely between each ultra fast pulse, what color would the laser appear to the naked eye?

Say you had a laser that pulsed faster than your eye could perceive it, so that it appeared to fire constantly. Imagine that in between each pulse the laser changed to every color of the rainbow for ...
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1answer
68 views

Plasma in solids

One way to create plasma is to focus a very powerful laser pulse to a small beam waist. In gaseous atoms, ionization will occur, yielding a soup of ions and electrons, which we call a plasma. But ...
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37 views

What are some mechanisms that can lead to unexpected/anomalous spectral lines

I am studying fluorescent spectroscopy (laser-induced fluorescence spectroscopy specifically). In a particular atomic spectrum, there are some unexpected lines not associated with any known ...
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1answer
47 views

Light and laser effects on surfaces. How and why do they cause a material to decay?

Anyone that's been in a museum knows that's it's forbidden to photograph mainly old or very deteriorated crafts using a flash, but what is the reason for this? I don't see how a burst of relatively ...
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1answer
136 views

Calculating the Rabi frequency of a pulse

If I apply a $\frac{π}{2}$ pulse of linewidth 5MHz centred at 99MHz to a nuclear spin also centred at 99MHz, is there a way to calculate a Rabi frequency of this interaction? I realise the Rabi ...
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1answer
105 views

Why does a near UV laser show as a green path in tap water?

i am using a 405nm laser and shining through a glass with regular tap water, also i noticed that it shows as an almost white path in the thick glass bottom, what causes this?
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1answer
47 views

How does yag Laser is LASIK work? And what is its lowest precision (till now)?

I am in a undergrad Vison Science class where the professor recently talked about LASIK surgery. In the surgery, a special type of laser that could heat up a specific point (a sphere actually) and ...
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2answers
134 views

Bending of laser beam wavefront

It is intuitive to me (correct me if I am wrong), that the direction of the wave vector in (real, not modeled) laser beam is not aligned with the direction of propagation everywhere in space. It means,...
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1answer
126 views

Would an incoherrent point source of light have any effect on a coherent

If you had a coherent laser beam that was split between reference and sample beams and the sample beam passes through the emission from a point source, there should be some disturbance right? I know ...
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72 views

Electromagnetically induced transparency(EIT) and Stimulated Raman adiabatic passage(STIRAP)

What is the connection between Electromagnetically induced transparency(EIT) and Stimulated Raman adiabatic passage(STIRAP) in case of lambda system? can we achieve STIRAP with different shapes of ...
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193 views

How can one recover the classical frequency-modulation Bessel sidebands from a quantum emitter in a harmonic well?

Consider an atom that emits at frequency $\omega_0$ that's located at a position $x$ that moves under the influence of a harmonic oscillator at frequency $\nu$. In both classical and quantum physics, ...
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24 views

Testing neutrino magnetic moment in ultra-intense laser fields

In some extended versions of the SM, Dirac neutrinos have a magnetic moment proportional to their mass. Could this be verified by studying neutrinos in ultra-intense laser field?
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1answer
42 views

Logic behind Coulomb explosion fusion?

Many experiments seem to have been done where the experimental setup consists of an extremely short, but intense laser pulse, impinging on e.g. deuterated plastic of some sort or some "jet" of nano ...
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89 views

Ionizing with 980nm laser

I have been looking at a 980 nm, 5-250 mw, 1 Hz to 1000 kHz pulsed IR laser. I understand that it takes 13.6 eV to ionize oxygen, and 15.6 eV to ionize nitrogen. Our pulses are only every 1,000,000 ...
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418 views

What is laser pumping?

I am having trouble understandingt exactly what this term mean. Can you explain it in layman terms? What i am guessing it means is having a laser do work on molecules by exchanging energy
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280 views

Can metals be ionized by radiation?

In gaseous state a laser can ionize metal atoms and create a plasma. But what about the solid state? Is a high intensity laser able to ionize a solid metal?
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48 views

How does shining, n, lasers of same or differing wavelengths at a small area increase the power at that area?

Is the effect of added lasers simply additive? Is there experimental evidence to confirm, or could someone refer me to this? If definitely seems obvious but I can't assume
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83 views

How does self-amplified spontaneous emission (SASE) work?

Due to the new laser in Hamburg, the XFEL, the following question arised: How does self-amplified spontaneous emission (SASE) work? There is an official article here http://www.xfel.eu/overview/...
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78 views

How can I block or not block a laser beam on a nanosecond scale?

I am doing an experiment in which I would like to block a laser beam, or allow it to be transmitted through on a nanosecond scale, based on the presence or absence of an electrical signal. When ...
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1answer
37 views

High-harmonic generation and few-cycle lasers

These two topics seem to go hand in hand: High-harmonic generation Few-cycle lasers I've been searching the web for some time trying to understand the relationship between the two, but I can't find ...
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Does a MASER beam stay un-dispersed like that of a laser?

We know that a laser beam has a very low dispersion rate. Does the same apply for a MASER (Microwave Amplification by Stimulated Emission of Radiation) beam?
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42 views

How far can diffuse photons from a laterally focused laser beam penetrate in the axial direction?

I have a question regarding practical laser focusing in the axial direction. More specifically, I was looking to get an idea of how large a distance in the axial direction a laser focused at 200nm ...
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1answer
33 views

What determines an emission wavelength after being pumped?

In this diagram, multiple emission lasing wavelengths are shown. What dictates which wavelength is lased? Is it random? Because this ion can be a four level or 3 level manifold due to the emissions.
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125 views

Why does a Gaussian beam shrink in diameter when approaching a focal point?

I'm basing my question on the above graphic. I've been trying to research this, but I'm having trouble getting it into my head. The caption says it follows the $\frac{1}{e^2}$ point on beam intensity, ...
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1answer
317 views

What if the optical length of a cavity is not a half integer scalar of the standing wave wavelength?

Pardon the confusing title, but I'll try and rephrase what I'm asking. Longitudinal modes in a wavelength of light require the optical length of the cavity to be such that the wavelengths need to form ...
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91 views

What exactly is Q-switching?

Some questions of mine spawned upon reading my lecture notes about Q-switching: "In a Q-switched laser we stop the laser from oscillating by altering some property of the laser cavity (otherwise ...
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444 views

Derivation for wavelength bandwidth

I've been told that for wavelength bandwidth $\Delta\lambda$, it can be shown that: $$\Delta\lambda = \frac{(\lambda^2 \Delta\nu)}{c}$$ Where $\Delta\nu$ is the frequency bandwidth and $c$ is the ...
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51 views

How does Gain-switching produce intensity spikes?

Gain switching is described in my lecture notes as "we simply control how long we supply energy to the laser for, and thus how long the laser remains above threshold for. As the laser only emits ...
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61 views

Are some wavelengths 'longer' than others spatially, and as such explain things such as longitudinal modes?

I'm currently learning lasers. In my research of mode-locking, I've stumbled across something called a longitudinal mode. The allowed modes of the cavity are those where the mirror separation ...
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460 views

Light-to-heat-conversion (LTHC)

Can somebody explain what is light-to-heat-conversion? how it happens, and what it requires to happen?
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100 views

Alpha/Beta radiation and photoionisation of air

Which type of radiation is more likely to lower breakdown threshold when using focal lense focused pulse laser,for example 1064nm Nd:YAG. I reed three studies that said free electrons are most ...
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3answers
377 views

In a laser, why are modes near the resonance frequency favored?

Before asking my question, I will illustrate how our lecturer treated a Fabry Perot interferometer, because my question is linked to this topic. Of all the different models to describe laser ...
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126 views

Laser beam extinction - what happened to the photons

I have seen some contributors (e.g. annaV) state that em-wawes are built up by coherent photons. Now imagine 2 identical thin laser beams (same intensity, same source using a beam splitter and prisms)...
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178 views

SHG conversion efficiency

I worked with a (rather complicated) laser system which eventually was able to produce about $1\,W$ of pulsed laser power and selecting the output wavelength via optical cavity ($1,0\mu m -1,5\mu m$). ...
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207 views

Photons inducing Directionality in Stimulated emissions of lasers

While studying stimulated emissions, I was wondering how could a photon introduce directionality into another photon emitted by an excited electron just by mere stimulation. How exactly does this '...
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396 views

What causes a simultaneous transition of an electron from a higher orbit to a lower one when exposed to a photon of suitable wavelength?

I know this is the basis of LASER action but why does an electron fall to a lower vacant orbit when exposed to a photon of energy equal to the difference between the initial and final orbit? The ...
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614 views

The difference between parametric and non-parametric linear and nonlinear optical processes?

There are plenty of linear and nonlinear optical processes, that can be divided into two groups: parametric and non-parametric (link). However, why are they called parametric (non-parametric)? What is ...