Output light field of a tapered fiber probe illuminating a vial filled with water containing trace amounts of the dye Rhodamine 6B. Coupled into the fiber are green (532 nm) and blue (488 nm) laser light under slightly different angles resulting in colorful patterns due to effects of diffraction, interference, scattering and fluorescence. The result is reminiscent of a human iris with the pupil staring intently at the bottom of the glass vial from close proximity.
—Nils Frederik Hasselmann and Mathias Hünecke, Nonlinear Photonics, Münster University, Germany
20 Feb 2018