Answers are grounded in this paper and cite their sources.
An exact scalar wave analysis of a directional coupler obtained by coupling two identical graded-index wave-guides having exponential profiles is given. This analysis has been used to study the validity of the widely used coupled-mode theory for studying such problems. The study shows that coupled-mode theory indeed leads to very good results for weak coupling but may lead to quite inaccurate results for sufficiently strong coupling.
No takes yet. Share an insight, caveat, or question.
Thyagarajan et al. (1981) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: