Radiation modes in arbitrary dielectric waveguides with homogeneous cladding can be split into a free-space field having its sources at infinity and a scattered field excited by the polarization of the core region. In a recent paper, Sammut [J. Opt. Soc. Am. <b>72</b>, 1335 (1982)] stated that radiation modes have the same orthogonality properties astheir free-space parts in lossless waveguides. An alternative derivation is established, and connection with earlier work is also reviewed.
© 1983 Optical Society of AmericaPDF Article