In a recent paper [J. Opt. Soc. Am. A <b>14</b>, 596 (1997)], S. Kaushik describes a modal theory of diffraction in which a number of features from scalar optics are generalized. The paper describes an S-matrix propagation algorithm that is characterized as being new and an improvement over earlier work. In a response to this paper, L. Li [J. Opt. Soc. Am. A. <b>15</b>, 1006 (1998)] disputes this claim and claims that the algorithm is well known and presents no significant improvement over earlier work. These criticisms are addressed in this reply. Specifically, it is shown that unlike earlier work cited by Li, the method described by Kaushik is a genuine S-matrix method since energy balance is automatically guaranteed for dielectric gratings, irrespective of truncation order. Further, it is shown that the algorithm is easier to relate to scalar optics and is computationally more efficient than the specific algorithms cited by Li.
© 1998 Optical Society of America
Sumanth Kaushik, "Vector Fresnel equations and Airy formula for one-dimensional multilayer and surface-relief gratings: reply to comment," J. Opt. Soc. Am. A 15, 1009-1011 (1998)