We have previously reported a high finesse fiber ring resonator.1 In this paper we report a novel tunable all-fiber laser with a fiber ring resonator structure formed by linking a directional coupler to a Nd3+ doped single-mode fiber. Previously reported doped fiber lasers cavities were either Fabry-Perot types with dielectric film mirrors on both ends of the fiber2,3 or, for a tunable laser, with an external grating as the wavelength tuning element.4 In both cases, high excess cavity loss was caused by coupling between the fiber end surface and the reflection mirror or grating, which cannot be avoided with these configurations. In our specially designed fiber ring laser, the directional coupler was used not only for coupling the fiber to become a ring cavity but also as a wavelength tuning element. In addition, there are no reflective mirrors or gratings in our all-fiber ring laser so that excess loss was very low.
© 1989 Optical Society of AmericaPDF Article