Questions tagged [laser-interaction]
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110
questions
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How does a light source / laser transfer energy to a material?
I am trying to understand the physics of how a laser is able to heat a solid. My understanding so far is that when photons are incident upon a body (e.g. a metal) the momentum of the photons is ...
0
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2answers
59 views
Why the dipole interaction term in the Hamiltonian has all diagonal elements to be zero in the energy eigenbasis?
I have been studying the semi-classical light matter interaction from the book, "Light matter interaction" by Weiner and Ho. They have defined the total Hamiltonian of a two level atom ...
2
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1answer
87 views
Why was the AC Stark effect only discovered after the laser was invented?
I was reading a paper about the theory of the AC Stark effect, and I was struck by the following assertion:
For instance, the first observation of the AC Stark effect initiated by the laser radiation ...
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0answers
14 views
Help finding a laser that will pulse with my signal generator
When I connect my 5mW red laser to my signal generator the laser fails to deliver clear square wave pulses once I go below the 2000ns mark.
The signal generator is capable of producing pulses as low ...
2
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1answer
57 views
Photon - Neutrino interaction
Suppose we have a laser source, that means a coherent laser beam formed by 'in phase' photons. Is it possible to calculate how many photons can change their wavelength in neutrino - photon interaction ...
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15 views
Time Response of Nonlinear Optical Materials
When reading about optical nonlinearities (and the nonlinear materials), a response time is often reported. I have been reading to try and understand the response time what these times mean. I ...
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17 views
Relationship between Intensity of a beam, energy, FWHM in time domain and FWHM of the transverse intensity distribution
Suppose I have a laser pulse whose intensity, energy and FWHM in the time domain I know is there a way to use this information to calculate its FWHM beam waist using this information. Thanks.
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0answers
26 views
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
40 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
22 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 ...
1
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1answer
25 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 ...
1
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1answer
47 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
45 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
45 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
16 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
12 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
83 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
127 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
17 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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51 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 ...
0
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1answer
104 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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0answers
14 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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0answers
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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8 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
37 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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0answers
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
134 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
57 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 ...
2
votes
0answers
42 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 ...
0
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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 ...
2
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0answers
27 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 ...
2
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0answers
186 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
82 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
572 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
104 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
38 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
35 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
84 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
96 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
127 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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0answers
85 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 ...
0
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1answer
54 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, ...
1
vote
1answer
35 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?
2
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2answers
264 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
59 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 ...
0
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1answer
38 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
112 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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0answers
53 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
55 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 ...
