COUPLED-MODE EQUATIONS FOR PERIODIC SUPERSTRUCTURE BRAGG GRATINGS

Periodic superstructure Bragg gratings are gratings in which the param eters vary periodically. Although one can determine their properties b y using the standard coupled-mode equations for the electric field env elopes, it is shown that; the analysis is simplified if one considers the super envelopes, i.e., the envelopes of the usual envelope functio ns. These super envelopes satisfy a set of (super) coupled-mode equati ons, which are formally identical to the standard coupled-mode equatio ns for a uniform grating. This shows that, within certain frequency ra nges, any superstructure Bragg grating acts approximately as a uniform grating. (C) 1995 Optical Society of America