Monolithic magneto-optical isolators for on-chip photonic integration

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

Non-technical: Optical isolators are optical analogs of electrical diodes: they allow light to be transmitted in one direction but block light propagation in the opposite direction. Isolators are essential components for photonic integrated circuits to prevent harmful cross-talk between different parts of circuits and stabilize circuit operation. However, current optical isolators are bulky devices not compatible with integration on photonic chips. This program aims to develop the device technologies based on novel magneto-optical oxide materials to create optical isolators amenable to direct integration with silicon photonic circuits. The isolator device developed through this program will have an immediate impact in the fields of optical communications and photonic signal processing. Besides data communication, it will also play a pivotal role in emerging applications such as spintronics, magneto-optical sensing, and magnetoplasmonics. The scientific research will be tightly integrated with Massive Open Online Course development, high school, undergraduate and graduate student training, as well as educational module design for K-12 classrooms. Technical: Optical isolators, devices that allow light transmission in only one direction, are critical components of photonic integrated circuits, and exemplify a larger class of nonreciprocal optical devices. Despite their critical importance, integration of optical isolators on-chip has been a challenging task due to the large lattice constant and coefficient of thermal expansion mismatch between magneto-optical oxides and common semiconductor substrates. This program aims at filling the gap by assuming a two-pronged approach involving both material engineering and device innovation. The program will develop a nonreciprocal isolator/circulator device using monolithically grown polycrystalline Cerium-doped Yttrium Iron Garnet as the magneto-optical medium, and incorporate novel device designs to enhance device performance. The research will lead to an isolator device simultaneously achieving monolithic integration, passive device operation, large isolation ratio, minimal insertion loss, and small footprint, as well as superior operation bandwidth, thus resolving the standing challenge of on-chip optical isolation.