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Wavelength selective coupling is demonstrated between the core of a D-shaped optical fiber and a multimode planar waveguide. The fabrication process consists of wet chemical etching of the D-fiber and spin coating or molding to produce the planar waveguide. This fabrication process is shown to produce weak coupling and long interaction length, which exhibits transmission dips with narrow wavelength linewidths. A comb filter is demonstrated with peak separations of 12nm, transmission dips of -20dB, and linewidths of 0.25nm. High sensitivity is demonstrated by showing shift in the transmission dips of -3.16 nm/degree C.

Elliptical core D-fiber is difficult to fusion splice to other types of fiber due to its small core and D-shaped cladding. The presented method of splicing D-fiber to PANDA fiber involves using E-fiber in a bridge splice. The E-fiber core is expanded to match the mode of the PANDA fiber. The D-fiber is then connected to the E-fiber with a low temperature splice. Total system loss for fibers spliced using this method is 0.72 dB with a polarization crosstalk of less than 25 dB.

This paper presents the analysis of a 2 cm long in-fiber polymer waveguide formed on the platform of a D-shaped optical fiber. Numerical simulations provide an understanding of the major loss mechanisms for feasible in-fiber polymer waveguide geometries. The primary loss mechanism is determined to be excitation of slab modes on the flat surface of the fiber with transition geometry being the next major contribution to loss.