There’s an explanation of the video on this post by Dr Mike Towrie. The crystals used to generate the laser light have some amazing properties.
“This shows the generation of light in a beta barium borate (BBO) crystal. It takes the picosecond light from a titanium sapphire amplifier in the near infrared, then doubles it to 400 nm in a BBO crystal then it takes this 400 nm light and focuses it into another BBO crystal. The 400 nm (pump) light is converted to different wavelengths dependent on the angle of the crystal. The movie shows the changes in colour.
The coloured light from this BBO can be amplified up in further 400 nm pumped BBO, then the colours from this can be frequency doubled, tripled, or mixed with other colours to create light tuneable from UV to Infrared. This means that we can study almost any chemical or biochemical.”