消逝波激励及增益耦合光纤三色激光辐射

Abstract

A Whispering-Gallery-Mode tricolor fiber laser is demonstrated by pumping and gain coupling with evanescent waves. The pump light is longitudinally coupled into a bare optical fiber immersed in a dye solution of lower refractive index. The dye molecules around the bare fiber are excited by the evanescent waves of pump light when their propagating along the fiber in a total internal reflection. Because the excited molecules are located within the evanescent field of Whispering-Gallery-Mode, a good spatial overlap between the dye gain and the evanescent field leads to a high pumping efficiency and a longer gain distance along the fiber. Once the bare fiber is inserted into three glass tube filled with Rhodamine 640, Coumarin 500 and Stilbene 420 dye solutions, respectively, Whispering- Gallery-Mode lasing oscillations at the wavelengths of 622-632 nm, 504-518 nm and 427-434 nm occur simultaneously, and a tricolor lasing emission is achieved in a single optical fiber. The relationship between produced length of lasing emission and pumping energy has also been investigated.