Multimode Interference Reflectors: A New Class of Components for Photonic Integrated Circuits

Multimode interference devices are very versatile components that are often used as components for power splitting or combining in larger circuits. In this paper, we present a new class of multimode interference couplers that are designed to reflect all or part of the light. The components can act as on-chip mirrors with partial out-coupling, or they can act as compact mirrors with full reflection. We present an overview of such devices, the basic theory and practical design guidelines. Their simple layout makes these devices easy to fabricate and tolerant to fabrication errors. We fabricated devices of several types and present the experimental results.