TLM NUMERICAL-SOLUTION OF BLOCHS EQUATIONS FOR MAGNETIZED GYROTROPIC MEDIA

The transmission-line matrix (TLM) method introduced by P. B. Johns mo re than two decades ago, is today commonly used for the numerical simu lation of wave propagation and transport phenomena. With increasing ev idence the method involves a rich potentiality of yet unknown applicat ions. In this pager a TLM solution of the linearized Bloch-Maxwell equ ations is presented using a nonorthogonal hexahedral mesh cell. Our ap proach is in fact very general and yields solutions of finite-differen ce equations perturbed by a linear or nonlinear causal function of the fields. Recursive relations between the scattering operations of the perturbed and unperturbed TLM processes are derived that are largely i ndependent of the kind of FD equations or causal function. A natural d escription of the perturbed TLM process is given in terms of recursive ly shifted (deflected) scattered quantities. Specifically the TLM solu tion of the coupled Bloch-Maxwell relations for gyrotropic matter in a ''strong'' static field is presented A gyromagnetic node is derived a nd the conditions for algorithm stability are inferred for finite spin -spin relaxation time. Numerical results are compared to experimental data at the example of a waveguide Y-circulator. (C) 1997 by Elsevier Science Inc.