The image shows the surprising observation of a visible rainbow of hues in a Near IR continuous wave Raman fiber laser. The laser is pumped only by NIR sources, and there is no visible light input. The visible rainbow is formed due to the 2nd and 3rd harmonic conversion of the cascaded IR Stokes wavelengths traveling in the core of the fiber. The image was captured using a standard DSLR camera, with a 30 second exposure time in the high power lasers lab in CeNSE, IISc.
—Santosh Aparanji, PhD Student at CeNSE, IISc
20 Nov 2018