Lasers Definition and 222 Threads

Free electrons can not absorb photons. Otherwise, the 4-momentum will not be conserved. That is what I understood from the very first lecture of QED. However, we do have the semi-classical picture for HHG - electrons are kicked out from the atom and get accelerated by the radiation field. I...

From what distance does the diffuse radiation of a „hair removal laser“ cease to be a threat? I apologize for the peculiar question, but I'm curious about the following matter: I walked past the window of a hair removal studio about 50 meters away earlier, and I noticed repeated bright red...

Here is my thought experiment: Let's say I attenuate a very short laser pulse to single photon intensity. Due to the uncertainty principle, I know the time of arrival of the photons, but not their energy. So let's reverse that by splitting the pulse in its spectral components with a diffraction...

I am looking for the thesis Frequency stabilized solid-state lasers for coherent optical Communications by Day, Timothy. I am working with laser stabilization so can anyone share this thesis? I am trying to understand the basic of this topic. This thesis is suggested by others but failed to get...

Objectives: - best path for optics needed to focus and "draw"/project a high resolution image onto a workspace around 500mm square (for a Laser Direct Imaging machine) - where to cost effectively purchase or make the optics necessary to build a prototype The problem: I need to project a high...

I read a paper about coherent surface plasmon amplification by free electron pumping in an article a few days ago. It seems to work as some kind of free electron laser-like light source, and I wonder how high the energy of photons can go in this way. Also I read in another paper about...

Hello ! I have a problem understanding how light works in multimode optical fiber. What do I mean in single-mode optical fiber there is single light which contains information. In multimode there can be multiple lights with multiple information. Like here 1st picture contains multiple...

I was wondering you if you could use a laser to put out a fuse or to stop combustion? Could you use some form of laser/laser cooling to put out an explosion mid-explosion?

I've often seen it said that hobbyist-grade UV lasers, sold for a few hundred dollars to those brave enough to buy one, cause a serious risk of blindness. In the literature I see reference to eye damage from as little as 5 mJ/cm^2, which seems absurdly easy to attain. And every time I think of...

I'm excitedly close to the end of proofing my latest novel, and as happens, tweaking of passages occurs. In this instance, a fleet of warships travel together in a collective warp space bubble that has inconsistent gravity, especially around the edges. To facilitate shuttle transfers between...

So (wildly simplistically) lasers work by photons being reflected between mirrors gaining energy on each trip through the medium until they break through the mirror on the output end. How many trips does that typically result in? 10s, millions? And thus the total distance is that count * the...

Is the following realizable : We suppose two non visible lasers whose direction and phase could be changed very quickly. The energy of just one laser would correspond to no possible transition in the atomic spectra of the molecules present in the atmosphere of the room. However if both...

Hello! Can someone point me towards some good books about laser from a practical/experimental perspective (maybe even a review paper). Most books I found spend a lot of time going through derivations and theoretical concepts. I would like to go deeper into that, too, at a point, but for now I...

print ('Calculate threshold, power, slope efficiency for different lengths of SC Laser') g = 510 # The gain of the laser, arbitrary value of 510 m^-1 was picked I = np.linspace(0, 0.03,5) #DRIVE CURRENT; 100 values of current, 'I', between 0A and 0.03AV = 1.8 #INPUT VOLTAGE; arbitrary value of...

This is really a nomenclature question. The radiation pattern of a typical laser diode has one axis with low divergence (the slow axis) compared to the other (the fast axis). I understand about antenna radiation patterns, spatial Fourier transforms (Fourier optics), etc. So I think I understand...

Hello everyone, I am a PhD candidate researching optical diagnostic techniques. I am looking to receive and give help with pulsed laser systems.

Summary:: What is the structure and how are minibands and minigaps in QC Lasers implemented Hello everybody, I have a question regarding the miniband and minigaps that are displayed widely in diagrams about the functioning of Quantum Cascade Lasers. How are this mini-gaps established...

I am sorry if these questions are basics, but I am not sure I totally understand the basics of how a laser works and the books I read are not totally clear for me, so any explanation would be greatly appreciated. So assuming we have a plane mirrors cavity and a gain medium in between, we create...

So I've read that varicose veins can be treated using fibre lasers. First, anesthetics are used locally to numb the limb and also act as an insulator for heat. Then, a small cut is made and a fiber is guided to the vein. Using laser light somehow the vein shrinks. This is what I don't...

So, I was working on autocorrelation for my pulse laser system and I started to wonder what is the difference between single wave with 400nm of wavelength and two 800nm waves overlapped. In the knowledge, I know of, is that wavelength is the length between two picks. And when it is pulse laser...

Many papers about random lasers mention the Q-factor of random lasers. Since a random laser has multiple peaks close to each other like shown in the figure. Does each of these peaks correspond to a unique random lasing mode, or is it just a single mode? Similarly what is the right way to...

Hi, I have been reading the Milonni and Eberly book "Laser": in one of the chapters they discuss the Oscillator Model. The treatment is quite straightforward, the Hamiltonian of the process is H=H0+HI where the first term is the "undisturbed" hamiltonian, and the second one is the interaction...

I don't understand how lasers can cut glass since it's permeable to light. Is it because all glass has some imperfections in it? I'm assuming it does *not* work that way but if someone could explain, that would be really helpful. I mean, glass is used to focus lasers so it's odd that lasers...

Hello, I wanted to ask about thermal lensing. Thermal lensing is when a temperature gradient from the center of the medium to the outermost part of the medium is created. This causes a varying refractive index throughout the medium. What I want to ask is: Why is the core of the rod(or any other...

My question is about the relative eye safety of infrared (##\lambda \gtrsim 1400 \ nm##) and ultraviolet (##\lambda \lesssim 300\ nm##) lasers. Both of these wavelengths are highly absorbed by the pre-retinal water content in the cornea, so they don't really penetrate into the retina. So one...

Can a setup be made such that the efficiency of spontaneous parametric downconversion approaches 100%? From what I have been told, this would be possible using classical input fields matching both the pump and output frequencies, but I am unsure if one could simply use laser of both frequencies...

From a practical standpoint, can we combine two (or more) lasers tuned to almost-but-not-quite identical frequencies to create distance-specific illumination? For instance, say we have a 1 micron laser and a 0.9999 micron laser which we combine through some beam-combiner optics. In theory I...

Hello, new here with lots of questions and minimal knowledge of physics. If I understand this correctly, when spontaneous emissions take place within a LASERs resonance chamber, they are not of the desired frequency nor are they paired with other coherent photons. So are they still desirable in...

Can Stimulated Emission in lasers be explained semi classically? If so, how?

Homework Statement An AFM uses a quadrant photo-diode to measure the deflection of the laser beam. Sketch the voltage in quadrants A, B, C and D as the tip travels on top of a single carbon nano-tube resting on a flat surface when the AFM is operating on tapping mode. Homework Equations Not...

Homework Statement Choose a technology such as MP3 players, lasers, medical imaging, or another that interests you. Research the internet and find out how it is related to the physics of light and waves. In approximately 100 to 150 words, write a paragraph explaining the link between our...

I was wondering whether intense UV light, tuned to the correct wavelength, could be used to split carbon dioxide and water molecules as a first step towards synthesizing liquid fuels.

Hello I am struggling to understand the concept of Quantum cascade lasers. I am doing research on a 20 period In0.33Ga0.67As (3.1 nm)/Al0.90In0.10As (7.2 nm) superlattice and would like to fully understand how a quantum cascade laser works. I also have not taken quantum mechanics yet so I...

With LHC currently at 13TEV design energy, and a planned higher luminosity upgrade, is the current plan to double the magnet strength for the current existing LHC to arrive at a 28-33TEV collider, or is it building a completely new future 100 TEV collider near Geneva where LHC is housed but in...

Say you have a red laser and pointed it at a ~175 nm antenna, then amplified the signal into a speaker. Would you then theoretically get a very high frequency audio signal (in the terahertz range, i realize this isn't practical)? My question is really on the nature of the light emitted from...

I was reading a news article about powerful lasers being used in missile defense systems, and I was wondering if multiple weak laser can work together to do the same job as one strong laser. For example can a thousand 1 Kw lasers in different locations be made to point at a single point on a...

Hello, If two lasers cross over, do tehy ionisate each other. If i have sensor in laser measuring ionisation going out etc can it see that laser 2 is crossing over it?

The combination of a half-wave plate followed by a polarizer is commonly used as a variable attenuator for polarized lasers. The idea is that the beam enters the half-wave plate, and you rotate the half-wave plate leading to a rotation of the polarization direction of the beam. As the beam is...

Hey all, I am looking for a reference that derives the optical Bloch equations for a two-level system driven by two near-detuned monochromatic radiation sources. Specifically, I am looking to substantiate a result I derived by following the same procedure as for a two-level atom driven by a...

I have a b.s. in physics and computer science from Western Washington University. Love the opportunity to be part of the conversation. Love modern optics!

We now have the capability to do laser launch. The problem is the initial cost outlay for the lasers is still prohibitive to launch a sizable payload. The estimate of the payload you can launch to Earth orbit dependent on laser power is about 1 kg per megawatt. So to launch thousand kilo...

I just had this thought while watching a video about the EM drive...basically using 2 lasers to bounce them off prisms inside an object to push the craft through space at a small but constant acceleration...could someone explain why this would not work?...please see attached image :)

Hello all. I am new here. I have an idea about defending the Earth from meteors using laser beams. I thought about using chemical lasers to burn the meteors. The first phase is that we use gas lasers if possible to create plasma by heating the gas and to use that plasma beam to strike at the...

What is a single-mode laser? what is a multimode laser?

Homework Statement Choose a technology such as MP3 players, laser, medical imaging, or another that interests you (Other than the cell phone). Research the internet and find out how it is related to the physics of light and waves. In approximately 100-150 words, write a paragraph explaining...

What could cause a laser source with fiber coupled laser diodes to have extreme loss of power? The laser diodes have a wavelength of 658nm and have an output rated at 60mW but it seems as though the optical channels actually output ranges between 58 to 70mW. During some troubleshooting I...

how was it done?

Hi! We have a projekt at the university and I have been thinking of creating a tiny tiny black hole after I've read some articles. I know one can create an artificial black hole with polarized laser pulses at a block of glass. And then one can measure a lot of things, usually hawkingradiation...

I've done my background research on this but i want to double check with others since the last time i did this i blew $30 because i shorted my diode. I got a new one but I'm really nervous about starting it up. These are the two parts...

I have multiple sources that have a max power output of 60mW, I am using a power meter that can read up to 200mW but when I connect directly to the source channel I get approximately 15mW or less. I have tried a different meter and I have tried different sources only to end up with the same...