Using the coupling between a standard single-mode fiber and single higher-order modes in a high-index overlay waveguide, we demonstrate a wavelength-filtering device with a channel-dropping response. Two types of filter are described. One uses a thin overlay waveguide, giving a single tunable dropped band response in the 1.2–1.6-μm wavelength region with rejection greater than 20 dB and an insertion loss of about 0.5 dB. The other uses a thick overlay waveguide and gives a comb-filter response with a dropped channel spacing of 13 nm with 20-dB rejection and an insertion loss of between 1 and 4 dB.
© 1987 Optical Society of America
Original Manuscript: October 14, 1986
Manuscript Accepted: January 6, 1987
Published: April 1, 1987
C. A. Millar, M. C. Brierley, and S. R. Mallinson, "Exposed-core single-mode-fiber channel-dropping filter using a high-index overlay waveguide," Opt. Lett. 12, 284-286 (1987)