多波型波导耦合本地正规波型的广义理论

在本文中作者提出了耦合本地正规波型的广义理论;它建立在作者在另一篇论文中提出的数学方法——“缓变系数法”的基础上。为了说明这种方法的应用,依次解出了考虑两个及三个耦合波型的缓变曲率波导弯曲问题。在两个耦合波型的情形下,所得结果与Louisell及Unger已得结果相符合。三个耦合波型的问题在以前的文献中尚未讨论过。本文讨论了所提出的理论及数学方法在其它方面的应用。

GENERALIZED THEORY OF COUPLED LOCAL NORMAL MODES IN MULTI-WAVE GUIDES

In this paper a generalized theory of coupled local normal modes is developed, which is based on the mathematical method-"method of slowly varying coefficients", introduced by the author in a previous paper. By this method, the set of ordinary coupled wave equations is transformed into a new set of equations for the local normal modes with much reduced couplings. To illustrate the applicability of the method, the all-important problem of bend with slowly varying curvature is solved by considering two and three coupled modes succesively. For the two coupled-modes case, our results agree with those by Louisell and Unger. Solution for the three coupled-modes problem has not been appeared in literatures heretofore. A numerical evaluation of the spurious modes in an S-shaped bend is given. Further applications are discussed.