I-Corps: Processing of high-performance optical isolator materials using magneto-optical garnets on Si wafers

The broader impact/commercial potential of this I-Corps project is the development of materials to improve communications. Current designs of certain components are limited to discrete bulk components that a have large footprint, need expensive raw materials and require a labor-intensive assembly processes. The proposed technology will greatly simplify optical isolator manufacturing and performance.

Applications for this technology include 5G wireless networks, data centers, and Internet of Things, and potentially photonic integrated circuits (PICs), which offer significant power, space and cost savings along with increased functionality for future communications systems.

This I-Corps project is based on the development of garnet-on-silicon optical isolator. Optical fiber technology has revolutionized communications, but expense and assembly difficulties have prevented step-function improvements. A hidden component in this expense is the optical isolator that sits in front of each laser to block reflections that otherwise interfere with the laser’s performance and lifetime.

Composed of a thick iron garnet film, grown on a single-crystal garnet substrate, the isolator is also the likely roadblock in the expansion of fiber success. The proposed technology enables the processing of high-performance magneto-optical garnets on Si wafers with oxide multilayers for optical resonance that enables isolation with 1000x thinner garnet films.

In addition, revolutionary garnet compositions and designs may provide magnet-free isolators. Together, these features may reduce cost and ease device assembly. The use of Si as a substrate also enables integrated device manufacturing, rather than “pick and place” assembly methods of commercial products today.

With low-magnetization garnet compositions that maintain high Faraday rotations, this technology will have negligible dipole fields, and devices already have been designed that do not require external magnetic bias. These large-scale, inexpensive, magnet-free garnets open many applications in communications.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.