Questions tagged [laser-interaction]

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Doppler cooling Ethanol

Is it possible to use laser cooling to cool Ethanol in it's gas phase? I've seen research on IR diode cooling when you reverse the electrodes but laser cooling was/has always been limited to atoms and ...
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1answer
30 views

Why is the frequency of emitted photon of laser different from the frequency of incident photon? [closed]

Why is the frequency of photons emitted from a laser different than the frequency of the incident photon?
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1answer
18 views

Why the transition of electron from an excited state to metastable state in a lasing medium is radiation less?

When an electron transitions from an excited state to the metastable state, no radiation is emitted i.e. a radiationless transition. My question is: Where does the energy difference between excited ...
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1answer
20 views

Number of Ionization event estimation

First of all, I am new in this field and therefore if I ask a silly question please forgive me. I have a gas-cell (say 3$\times$3$\times$3 mm$^3$ volume) filled with a N$_2$ gas. The number density is ...
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1answer
43 views

How is three-dimensional laser cooling possible?

I am a bit confused about laser cooling an atom in all three dimensions. I think I have understood the one-dimensional case: The atom absorbs doppler-shifted laser light and the momentum in this ...
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1answer
24 views

How to put laser field into the Hamiltonian of the Schrodinger equation of a 3-level quantum system?

I read a paper about using femtosecond laser to control a 3-level quantum system. The author wrote the Schrodinger equation for the system and wrote the expression of the laser field. But I still don'...
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1answer
39 views

Units of energy and frequency

I read a paper about using femtosecond laser to process an atom. The units used in the paper bothered me. I have four questions. (1) Why the unit of energy is cm$^{-1}$? (2) It seems that the author ...
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0answers
12 views

Features of plasmon and surface plasmon polariton

What is the difference between surface plasmon polariton and plasmon in the Hamiltonian? So let's say that I can diagonalize the Hamiltonian of the system I am studying no matter how complicated that ...
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0answers
11 views

What is box shape in ion beam drivers for ICF?

What is the meaning of box shape in the ion beam pulses? i mean in plasma we say the ion beam irradiating the capsule is box shaped. what does it mean?
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1answer
61 views

What is the difference between ion beam and laser?

What is the difference between laser beams and ion beams, especially in inertial confinement fusion? In inertial fusion, we use lasers as well as ion beams for driving the reaction. What is the ...
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1answer
115 views

How to kill an insect without touching it? [closed]

Apart from the interception by a sufficiently powerful laser, what would be the means to neutralize (kill/repel) an insect in full flight and indoors (so no water, pepper, etc), and without touching ...
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1answer
16 views

How to calclate Drude dielectric function vs probe energy from time resolve spectroscopy?

How can I calculate drude dielectric function vs probe energy (in eV) form differential transmittance vs delay time plots.
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22 views

Random walks and the Doppler limit in laser cooling

I have a question about some conflicting definitions I have encountered regarding the diffusion coefficient in random walks of laser cooled atoms. I was wondering if someone here may be able to clear ...
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1answer
53 views

How to calculate the Rabi frequency of a pulsed laser?

I read that the Rabi frequency $\Omega$ for a constant intensity laser with intensity $I$ is given by $$\Omega=9.95 \times10^7 \sqrt I$$ from Equation 3 in this paper. For a pulsed laser, how does ...
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13 views

Photoelectrons could be detected in position space rather than momentum space?

In experiments, to study the interaction between atoms and light, experimenters use lasers ( i.e. coherent light) that interact with a gas of atoms. This treatment is pure statistics. To be more ...
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40 views

Simluation of time-resolved fluorescent spectrum

I'm trying to model time-resolved fluorescent spectrum of diatomic molecules. My questions concern some formulas in "Atoms, Molecules and Photons An Introduction to Atomic-, Molecular- and Quantum ...
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5 views

Stark shift is for bound states and ponderomotive energy for free electron, is it true?

A free electron has low chance to collide with a photon but it can gain an energy Up related the pondermotive force of laser field. But when the field turns off the electron lose this energy and ...
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1answer
30 views

Classical treatment of light-matter interaction, why light state changing is ignored?

In a semiclassical treatment of light-matter interaction commonly we treat atomic target (atom, surface, molecule, etc) quantum mechanically and the light is considered as a classical wave function ...
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18 views

Is it possible to cause condensation in air using low energy pulsed lasers?

I read here that femtosecond pulsed lasers can cause condensation in the air. They primarily work by ionizing air, thereby creating charged hot spots around which water particles condense. But the ...
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0answers
12 views

Oppossing Laser Beams Cause One Beam to Disappear [duplicate]

I posted a video early where I asked the question about opposing laser beams appearing to turn one laser off. Further experiments, however, have demonstrated that it is interference at play not that ...
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2answers
125 views

Opposing Laser Beams Turns One Laser Off

When I send two separate laser beams directly into each other one of the beams goes completely out. These are inexpensive 5mv red diode lasers. What’s happening inside the laser to make it “turn off”? ...
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1answer
56 views

New concept - fiber optic gyro

Dear people of laser science, my understanding of fiber optic gyro is: a single laser beam runs into a cube splitter, then the 2 beams are driven into the opposing ends of a fiber (coil). Then in the ...
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0answers
39 views

Rigorous adiabatic elimination for $N$-state quantum system under harmonic perturbation

I am interested in a rigorous derivation of the coherent evolution of a quantum system with $N$ states under the application of a harmonic perturbation. I have read several articles about the use of ...
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1answer
13 views

Behavior of collimated beam inside tubular first-surface-mirror

Picture a cylindrical tube, the interior surface of which is a 1st-surface mirror coating. Visualize the diameter of this tube as circumscribing an equilateral triangle with sides A,B,C. The plane ...
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0answers
26 views

Is it possible to produce shock waves in air using low intensity pulsed lasers?

Air has about 0.04% carbon dioxide. Carbon dioxide has a very strong absorption band around 4.2µm. Let's say I used a nanosecond pulsed 4.2µm MIR source and targeted it into air, part of this would be ...
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0answers
97 views

Calculating Laser Beam Intensity Absorbtion

This question pertains to the ability to calculate the laser beam intensity , at a particular point in time when using lasers for the purposes of Cutting and Engraving Materials. The parameters at ...
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1answer
66 views

What is the exact usage of internal heat generation term used in a general heat conduction equation?

∂/∂x (λ ∂T/∂x)+ ∂/∂y (λ ∂T/∂y)+ ∂/∂z (λ ∂T/∂z)+ q_v= ρC_p ∂T/∂t------1 T - Temperature (Temperature of the material) ρ - Density of the material C_p - Specific heat capacity of the material t - ...
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1answer
415 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
76 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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0answers
32 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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1answer
33 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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0answers
79 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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1answer
77 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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0answers
104 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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74 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
47 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
33 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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2answers
210 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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0answers
51 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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1answer
35 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
100 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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50 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
51 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
201 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
122 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
48 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
199 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
181 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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100 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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1answer
241 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, ...