Abstract

Grating reflectors are interesting as narrowband filters for optical fiber wavelength-division multiplexing. In particular, gratings directly in the evanescent field of a guided mode offer possibilities for all-fiber in-line components. Previously, evanescent grating reflectors have been demonstrated with single-mode fibers.¹ Although efficient reflection appears possible, single-mode reflectors have the disadvantage of needing an element such as a directional coupler to extract the reflected signal returning on the same fiber. The problem is that the forward signal is also split by the coupler. Such an arrangement incurs a minimum of 6-dB loss to the extracted reflected signal.

© 1986 Optical Society of America