On-chip optical isolators for fully integrated photonic devices

Optical isolators, devices that only allow unidirectional light propagation, constitute an essential building block for photonic integrated circuits (PICs). As the counterpart of electrical diodes in photonics, isolators play a critical role in PICs by preventing harmful feedback between different parts of the circuit. For example, an isolator is often used to protect a laser from destabilizing feedback or damage from back-reflected light. The need for on-chip isolation becomes imperative as the level of photonic integration continues to scale, since unwanted reflections between the many integrated devices are common and can be highly disruptive in a complex optical network. Development of on-chip isolators has been hampered by the incompatibility of traditional magneto-optical materials with monolithic integration on semiconductor substrate platforms. RMD aims to solve this problem using atomic layer deposition (ALD) to produce magneto-optical garnet films. In addition, RMD will explore a novel isolator architecture to enable scalable integration of optical isolators with standard photonic foundry manufacturing processes.