Abstract

Rare-earth-doped optical fibers have become an important class of laser active gain media with many diverse applications. One area that is attracting considerable research effort is the development of single-frequency fiber lasers for use in coherent communications networks and high-resolution spectroscopy. Many different approaches have been used to control the oscillating frequency of the fiber laser.¹⁻⁴ Recently, we have developed a novel continuous-fiber filter based on the coupling of light from the fiber core to a planar waveguide.^5,6 Unlike conventional fiber-based filters, e.g., fiber Fabry-Perot filters,¹ this is a continuous fiber device and operates in a transmission mode as opposed to a reflection mode, which is the case for fiber Bragg reflectors.

© 1995 Optical Society of America