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Need cheap lasers with exact frequencies

geon

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Hi guys I'm new to this forum and I have no idea about prices of lasers, I need to conduct an experiment with two lasers and I need to control exactly the difference of their wavelengths. I know you can shift the wavelength with a refractive media but I was wondering if there is another way.. I know that led lasers are not very good for my application I doubt they make phosphors even close to the frequency spacing I need..I read that they sell tunable lasers but how expensive are these? If there is no other way I will make the lasers on my own.. but this will take a lot of time..hehe:undecided: actually they make lasers close to what I want now all I need is a 401,73 nm laser...if they're not exact spacing it will not work ... who wants to make a quick experiment with a wavelength meter and two lasers?
 
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You're looking at thousands to tens of thousands of dollars. If you're actually serious, maybe contact a company such as this to see what they can build for you.
 

jArdi

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Jan 21, 2013
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out of curiosity, what are you planning on doing? Some members here can help with some suggestions/alternatives if we knew exactly what was going on :) do you just want to get the exact spacing for measurements and thats it?
 

geon

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The lasers don't have to be totally monochromatic but power is dependent on particular photon emission , so it doesnt have to be exact .. you can try it yourself with a 400-405nm and a 650nm laser.
 
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I need to conduct an experiment

What experiment might that be?

I need to control exactly the difference of their wavelengths.

How exactly? Like 1nm precision?

I know you can shift the wavelength with a refractive media

Arguably, yes, but the photon's energy (the frequency) remains constant. A red photon in glass may technically have a wavelength of around 440nm, but it's still a red photon.

I know that led lasers are not very good for my application

There is... no such thing as an LED laser. If you're talking about LEDs, the spectrum is indeed quite broad.

they make lasers close to what I want

What DO you want?

all I need is a 401,73 nm laser...

That can be done by cooling a typical blu-ray diode. The line width is not narrow enough to make the decimal places matter though.
 

geon

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sorry I should have said solid-state lasers but aren't lasers made from doped semiconductors the same material that leds are made from the only difference is that lasers emit a specific wavelength?..

The experiment has to do with plasmons.. and it's a long shot.. it has to do with surface plasmonic re-emission , if it works it will glow white light (when a surface with proper material is illuminated) but I can't be sure about it.. the wavelength doesnt have to be exact if there are two photons with this exact wavelength spacing I'm hoping they will generate new particles durring plasmonic re-emission..so the result is unknown and the most probable is to emit only some white light..

wavelength is all that matters when interactions with atoms come into play I think.. I have other uses for it as well... but I can't afford expensive lasers..
 
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aren't lasers made from doped semiconductors the same material that leds are made from the only difference is that lasers emit a specific wavelength?

No, LEDs have no stimulated emission taking place. Laser diodes use stimulated emission like all lasers.

Is it a single wavelength? That depends on how many decimal places you go out. Even a HeNe doesn't have only one wavelength if you go out several significant digits. See spectral linewidth.
 
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geon

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it doesn't have to be 100% exact but the more exact the better.. :) maybe I should look into powerful LEDs instead .. although I need laser light.. I think it's better to put if off for now I'm a little behind with photonics atm.. and some thousands to tens of thousands of dollars short :eek:
 
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geon

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900$ for a 250nm led and 10k$ for 250nm laser... whoaaah.. why so much for a freaken led?
 
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If you have to ask, you're way out of your league dude.

Here's a hint: LEDs that can produce wavelengths that short are hard to manufacture.
 

cev1

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Depending on exactly how precisely you need to control the difference, you can build all the necessary apparatus for way less than Toptica costs. The problem is that you will spend years trying to get it right unless you work with someone who knows what they are doing.
 

LSRFAQ

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Search terms for Google:

Set one
"Review of Scientific Instruments Diode Laser Grating Littrow Feedback Tunable PDF Littman-Metcalf"

Set two:

"temperature tunable diode laser"

Set Three

"ECDL laser diode"

Take out RSI from list one if you want to see the freebie papers.

Link to home made tunable diode lasers, caution, the man is a genius and has NO budget, yet does lab grade work.

http://redlum.xohp.pagesperso-orange.fr/laser/ECDL.html

For the frequency references, use "optogalvanic spectroscopy" techniques with neon or argon lamps to check the tuning of the the laser.

For the short term, you can tune a single mode diode with reflections from a carefully positioned microscope cover slide.It acts as a etalon.

If you need really stable, get a cheap HENE laser, and build the stabilzation circuits mentioned in Sam's FAQ under "homemade stabilized hene"

Steve
 
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