# Tagged Questions

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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### Experiment using a laser beam

I need to come up with an experiment to conduct for my physics class. So far, I'm stuck at the use of lasers. What plausible experiments can be done using lasers that haven't been done before, and ...
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### Clear explanation of the difference between a laser's frequency stability and its coherence length

A red laser with a wavelength of 600nm would have a frequency of 5E14 Hz. If it had a frequency spread (noise or finite cavity Q) of 6 MHz, we'd say it has a coherence length of 50 meters. You could ...
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### Photons inside laser cavity

In a laser, the pumping mechanism excites an electron to a metastable state. This electron remains in the metastable state for a longer time and is de-excited to the ground state by emitting photons (...
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### Free Optics Simulation Programs

I'm having an extremely difficult time finding an optics program that is easy to use and offers accurate physics simulations. I'm not asking for much, I just want to be able to simulate a laser going ...
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### How does optical phase modulation produce photons with different frequencies?

The classical description of electro-optic modulators is an index of refraction that depends on the applied voltage. For example, for a sine modulation $\sin(\Omega t)$, a monochromatic laser of ...
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### Calculation of temperature distribution in bulk glass due to laser heating

I'm trying to figure out how to simplify the problem where laser pulses are focused to a small spot in bulk glass. The waist of the beam is about 20 microns. At the wavelength used there is only two-...
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### Jones formalism for calculating quarter waveplate angle for circular polarized light

I am planning to change the polarization of a vertically linear polarized laser to circular polarized light with the help of a quarter waveplate. I know the final result: I have to rotate the fast ...
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### Supercontinoum lasers

In my work I've encountered the phrase "supercontinuoum (CW) laser" quite a bit. After reading the wikipedia page, I'm interested in a more theoretical introductory. I'm mostly interested in ...
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### does anodizing aluminum change its reflectivity at 532nm

Does anodizing aluminum change its reflectivity at 532nm? I have tested percent reflection of highly polished aluminum at 532nm. I am concerned that the aluminum will oxidize and change reflection ...
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### Curvature of a laser beam with M2 parameter greater than 1

Usually a laser beam is characterized with parameter $M^2$ which shows how much does the beam size diverge in comparison to the Gaussian beam. $w=w_0\sqrt{1+M^2(\frac{z-z_0}{z_R})^2}$ But what in ...
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### Free Electron Lasers (FEL) and limits on laser wavelength

Free Electron Lasers are based on Synchroton coherent radiation when a collimated electron beam suffers trajectory curvature due to a strong bouncing magnetic field inside an undulator. Free Electron ...
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### How do laser triangulation sensor reflection obeys law of reflection?

I find it hard to understand how laser triangulation sensor work considering this image The laser beam form the angle of $90^o$ with the surface so how can the reflection beam form the different ...
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### 7 W medical laser without any precautions?

Today I got some medical laser treatment to treat some tendon irritation. The doctor used a red or IR laser with 7 W of power. He casually applied the laser onto the knee and was panning over the area....
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### How does one calculate the minimum spectral linewidth in cm$^{-1}$ of a pulsed laser with pulse duration of 10 fs?

I calculated the minimum spectral linewidth given here using the uncertainty principle that $\Delta E\,\Delta t =h/2\pi$. Will this be correct?
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### How do laser “tape measures” work?

There is a device available for about $\$40$, which fits in the palm of the hand, runs on two AA batteries, and can measure distances up to$50\,{\rm ft}$to an accuracy of$\sim \frac{1}{8}''$($\sim ...
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### Near perfect reflectors and LASERs

What would happen in a hypothetical scenario in which a LASER strikes a near perfect reflector (like the ones made by Jason Valentine at Vanderbilt, which reflect 99.7% of visible infrared light). I ...
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### Creating nanosecond pulses from a CW laser source

Experimental setup question. If anyone aware of a technique to create pulses of several nanoseconds at a around 10Hz repetition rate from a CW laser source?
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### Laser resonator analytic formula for sum of modes

For a sum of N modes in a resonator with identical phases, find an analytic formula for the pulse shape in the limit of many modes. Use the analytic expression for the sum of a geometric series. ...