Besley, JLove, JohnLadouceur, FrancoisMaxwell, G2015-12-130306-8919http://hdl.handle.net/1885/71754We investigate the higher-order supermodes of symmetric buried channel waveguide (BCW) couplers with cores of square, rectangular, and trapezoidal geometries. We show how the cutoff wavelengths of these supermodes can be used to interpret the spectral response of a practical single-mode BCW coupler. Our results highlight the design constraints imposed by second-order supermodes. We also compare the behaviour of these couplers with that of circular-core couplers to illustrate how the geometry of each core affects the coupler cutoff characteristics.Keywords: Optical fibers; Optical waveguides; Plasma enhanced chemical vapor deposition; Rectangular waveguides; Spectrum analysis; Buried channel waveguides (BCW); Waveguide couplers Planar waveguides; Planer couplers200210.1023/A:10150401190692015-12-11