Modulate a laser's wavelength? What are the inner workings of a laser, and is it possible to change the wavelength mechanically? Are there any lasers that can change wavelength?

  • $\begingroup$ How about pulsing the laser and modulating the pulse frequency? $\endgroup$
    – Eric S
    Commented Dec 9, 2017 at 14:49
  • $\begingroup$ Would this be easier to encode, or have any data-transfer benefits over standard digital transmission? $\endgroup$ Commented Dec 9, 2017 at 23:28
  • $\begingroup$ It's just a curious question. $\endgroup$
    – bobiscool
    Commented Dec 11, 2017 at 17:59
  • $\begingroup$ You might be able to start with a broad-spectrum light source, spread it out by wavelength, then pass the particular wavelength of interest with a optical gate. $\endgroup$ Commented Dec 13, 2017 at 12:54

1 Answer 1


No, it is not possible to modulate the wavelength of a laser. The particular wavelength of light is determined by the amount of energy released when an excited electron drops to a lower orbit, which in turn is defined by the specific glass/crystal/gas used in the laser.

Even if you could design some sort of mechanism to swap in/out different emission media to make step-changes in wavelength, you would not be able to reproduce a meaningful signal.

  • $\begingroup$ Are there any lasers who's wavelength is determined by the distance between the two mirrors? $\endgroup$
    – bobiscool
    Commented Dec 11, 2017 at 17:58
  • $\begingroup$ No, there are not - the wavelength is already set by the time any photons hit a mirror. Have a watch of this if you're still confused: youtube.com/watch?v=y3SBSbsdiYg ["How lasers work (in theory) - minutephysics] $\endgroup$ Commented Dec 11, 2017 at 22:48
  • $\begingroup$ What if you interferenced 2lasers ir am i just tired? $\endgroup$
    – joojaa
    Commented Dec 13, 2017 at 16:58
  • $\begingroup$ Taking two lasers at different frequencies, and 'interferencing' them could create a third frequency linked to the 'beat' between them, but this would still not allow for the continuous variation in frequency required for FM transmission, nor would the wavelength of any one laser have been modified. $\endgroup$ Commented Dec 14, 2017 at 10:45

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