Laser driven leap forward: the next generation of magnetic devices for controlling light is born

Recently, a new laser heating technology developed by a Japanese research group has paved the way for advanced optical communication equipment by integrating transparent magnetic materials into optical circuits.

This breakthrough was recently published in the journal Optical Materials. It is crucial for integrating magneto-optical materials and optical circuits, which has been a significant long-term challenge in this field in the past. It is expected to make progress in compact magneto-optical isolators, miniaturized lasers, high-resolution displays, and small optical devices.

Laser heating of transparent magnetic materials

Specifically, researchers from Tohoku University and Toyohashi University of Technology in Japan have developed a new method for manufacturing transparent magnetic materials using laser heating.

"The key to this achievement lies in the creation of 'cerium substituted yttrium iron garnet' (Ce: YIG), a transparent magnetic material that uses specialized laser heating technology," said Taichi Goto, associate professor and co-author of the Institute of Electronic Communications (RIEC) at Tohoku University in Japan. "This method breaks through the key bottleneck of integrating magneto-optical materials with optical circuits without damaging them - a problem that hinders the progress of miniaturization in optical communication equipment."

Magnetic optical isolators in optical communication

Magnetic optical isolators are crucial for ensuring stable optical communication. They are like traffic lights directing, allowing them to move in one direction but not in another direction. Integrating these isolators into silicon-based photonic circuits is challenging as they typically involve high-temperature processes.

Due to this challenge, Taichi Goto and his colleagues focused their attention on laser annealing - a technique that selectively heats specific areas of materials using lasers. This enables precise control, affecting only the target area without affecting the surrounding area.

Previous studies have used it to selectively heat bismuth substituted yttrium iron garnet (Bi: YIG) thin films deposited on dielectric electron microscopy. This allows Bi: YIG to crystallize without affecting the dielectric electron microscopy.

However, when using Ce: YIG (which is an ideal material for optical devices due to its magnetic and optical properties), problems arise as exposure to air can lead to unnecessary chemical reactions.

To avoid this situation, researchers have designed a new device that heats materials in a vacuum, which means there is no air and laser is used. This allows for precise heating of small areas (approximately 60 microns) without altering the surrounding materials.

The impact on optical technology

Goto added, "The transparent magnetic materials created through this method are expected to significantly promote the development of compact magneto-optical isolators, which is crucial for stable optical communication. In addition, it opens the way for the manufacture of powerful miniaturized lasers, high-resolution displays, and small optical devices."