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There are red, green, and blue lasers out there but i can't find a white laser? how hard is to make one? Is it possible?

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closed as off-topic by Carl Witthoft, Fred, Wasabi, Solar Mike, Mahendra Gunawardena Jul 8 '18 at 2:32

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  • "This question does not appear to be about engineering, within the scope defined in the help center." – Carl Witthoft, Fred, Wasabi, Solar Mike, Mahendra Gunawardena
If this question can be reworded to fit the rules in the help center, please edit the question.

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Its not hard- it bends the idea of what a laser is. Lasers have a single (or very narrow) wavelength of light emitted. There is no "white" wavelength- its just what your eye perceives from a (relatively) full spectrum of wavelengths.

This is generally considered by the scientific community to be an advantage, not a disadvantage. You can do many cool things with a single wavelength that you can't do with a broad spectrum.

You could potentially make a white-ish laser by syncing up many different lasers to make a combination beam that your eye perceives as white. This would be a very difficult engineering problem though, if you actually wanted a spatially coherent laser. Thanks to OpticalResonator for pointing out some folks who managed to do it in a single crystal, which is pretty wild.

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    $\begingroup$ It has actually been done in 2015, see this paper nature.com/articles/nnano.2015.149 $\endgroup$ – OpticalResonator Jul 6 '18 at 16:51
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    $\begingroup$ Whoa, cool! I considered that possibility but omitted it because I wasn't sure it would even count as a laser since it doesn't make any sense for it to be temporally coherent. Do they address that point in the full text (I'm stuck on the paywall)? $\endgroup$ – ericksonla Jul 6 '18 at 16:56
  • $\begingroup$ I‘m sadly also stuck there :P it does come from one single laser active medium, with 3 layers that emit on 3 wavelengths, so I would assume that it is coherent $\endgroup$ – OpticalResonator Jul 6 '18 at 17:00
  • $\begingroup$ Some lasers have a narrow frequency spectrum in their emissions; other lasers (typically used for pulsed emission) emit over extremely broad spectra that can span close to an octave. Narrow-band emission can seem like the entirety of laser science for people who work with CW lasers, but it is not the only useful mode of operation. $\endgroup$ – E.P. Jul 6 '18 at 23:25

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