Single- and Dual-Wavelength Fiber Ring Laser Using Fiber Microdisk Resonator

We demonstrate a fiber ring laser using a fiber-based microdisk resonator as the wavelength filter and a 2-mm-long tapered fiber as the coupling component. The fabrication process of the microdisk and tapered fiber is described. Depending on the optical coupling between the microdisk and the tapered optical fiber, either the fundamental or higher order transverse optical modes in the axial direction of the microdisk can be excited. When only the fundamental transverse mode of the microdisk is excited, the fiber laser operates at single wavelength and is polarization-insensitive. When the higher order transverse modes are excited, the fiber laser exhibits polarization sensitivity, and can operate in either single or dual-wavelength operation. A small spectral separation of 0.62 nm is achieved for dual-wavelength operation.