Misalignment effects on the spectral characteristics of edge filters based on singlemode–multimode–singlemode (SMS) fibre structures are investigated numerically and experimentally. A modal propagation analysis is used with a set of guided modes calculated using the finite-difference method to determine the transmission loss of the SMS-based edge filters. A limit for the tolerable misalignment of the SMS fiber-based edge filter is proposed, beyond which the spectral performance of the SMS structure degrades unacceptably. The numerical results are verified experimentally with good agreement.
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