Les Wright Is "Shaking Molecules Until Laser Light Comes Out" with a Homebrew Raman Laser
With an aluminum tube filled with DMSO and a high-power tattoo removal laser, Wright shows off a homebrew Raman laser device.
Self-described "amateur scientist" Les Wright, of Les' Lab, has published a video demonstrating how to make a "simple" Raman laser — by "shaking molecules until laser light comes out."
"What if I told you it was possible to get a wide range of molecules to emit laser light in the visible portion of the spectrum — if you shake them hard enough," Wright says by way of introduction to his latest video. "Let's take a look at a remarkably simple device: the Raman laser."
First created in 1962 by Gisela Eckhardt and E. J. Woodbury, the Raman laser works by absorbing "pump photons" and re-emitting them as laser-light photons, or "Stokes photons," at a lower frequency. The trick: Raman scattering, first predicted as an inelastic version of the elastic Rayleigh scattering by Adolf Smekal in 1923 before being formally discovered by physicist C. V. Raman in 1928 — showing that while most scattering of light in a material results in photons retaining their energy, a small percentage of photons end up with a change in energy.
By adjusting the medium through which the pump photons travel and the wavelength of the pump source itself, it's possible to tune a Raman laser to any wavelength — making it a very useful tool. in Wright's case, the medium is dimethylsulfoxide (DMSO) fitted into a custom-made aluminum resonator with quartz windows. The pump photons, meanwhile, come from a surprisingly simple source: a tattoo removal laser.
By stimulating Raman scattering within the DMSO, Wright is able to transform the 532nm green light coming out of the original laser into a new 628nm red laser beam — proven through measurements using a DIY spectrometer Wright developed two years ago, which combines a commercial diffraction-grating spectroscope with a Raspberry Pi High-Quality Camera Module and a Raspberry Pi 4 single-board computer.
Wright's full video on the Raman laser project is embedded above, and also available on his YouTube channel — with links to learn more about the topic in the video's description.