Two-wavelength-range whispering-gallery-mode fiber laser pumped by evanescent wave

Abstract

A cylindrical micro-cavity was made by immersing a silica optical fiber into a low refractive index dye solution.Pumped by evanescent wave along the fiber axis, dye gain was confined in the evanescent field of whispering gallery mode （WGM） of the fiber, which led to a high pumping efficiency and a long gain distance along the fiber axis. When the fiber was immersed into Rhodamine 6G and Rhodamine B dye solution with the same concentration of 8×10-4mol/L but separated to two parts, WGM laser emissions in the wavelength ranges of 567—576nm and 592—600nm were observed; when immersed into Rhodamine B dye solution with two concentrations of 8×10-4 and 8×10-3mol/L, WGM laser emissions in the wavelength ranges of 588—595nm and 600—618nm were observed. WGM laser emission in two different wavelength ranges in a single optical fiber was realised, which formed a new kind of WGM laser, the two-wavelength-range WGM fiber Laser.