Columbia-SUNY Team Slices Magnetic Crystal; Applications Seen For Miniaturized Optical Devices

November 12, 1997

In laboratories at Columbia University, scientists are bonding light and electricity.

They have taken the first important step toward creating a microchip that combines electronics and its optical equivalent, photonics. The technology could simplify fiber optic communications and lead to the development of such miniaturized optical devices as tiny lasers and implantable medical sensors.

The Columbia scientists, working with colleagues from the State University of New York at Albany, have bonded an ultra-thin sheet of magnetic garnet, a photonic material that transmits light in only one direction, to a semiconductor, a component of microelectric circuitry.

"Ultimately, manufacturers will be able to combine optical and electronic capacity on the same silicon crystals, which are superior electronics platforms," said Richard M. Osgood, Higgins Professor of Electrical Engineering and professor of applied physics and co-author of the research.

A crucial step was slicing an ultra-thin sheet -- 9 microns, or millionths of a meter, thick -- from the magnetic garnet crystal, the subject of a scientific paper published in the Nov. 3 issue of Applied Physics Letters. Columbia has applied for a patent on the new technology.

Professor Osgood and the co-inventor of the new technology, Miguel Levy, senior research scientist at Columbia, have already begun to receive requests for single-crystal magnetic garnet films from other laboratories around the world, for such diverse research applications as microwave electronics and optical isolators. Columbia is the only institution that can produce the thin films.

The work took place at Columbia's Microelectronics Sciences Laboratory and at the Columbia Radiation Laboratory, both in the Fu Foundation School of Engineering and Applied Science. The research group included two materials scientists at the State University of New York at Albany, Hassaram Bahkru and Atul Kumar, who assisted in processing the garnet used in the experiments at SUNY Albany's ion accelerator.

"I'm excited that this technology can be used to build a whole new range of miniaturized systems, from medical sensors to ultra-small, powerful laser systems," Professor Osgood said.

Miniaturized optical processors for fiber optic telecommunications are also possible. Currently, optic messages travel by laser light to an isolator that prevents destabilization of the laser by outside interference, then to a modulator that imprints a signal, then to a multiplexer that combines signals of different wavelengths, each of which can carry a different message. A similar system is required at the receiving end to decode the light message into sound or picture.

"Right now, these are all very bulky devices," Dr. Levy said. "If you could put all these optic circuits on a chip, it would be cheaper, more efficient and sturdier, and there has been a lot of research geared towards integrating these components. Our work is an important step in this direction."

Such integration between photonics and electronics had not been possible because garnet and other magnetic crystals cannot be grown on a semiconductor substrate. Magnetic isolators cannot be made efficiently on any material other than magnetic garnets. Thus the need to place garnet crystals on semiconductors, providing a bridge to an already mature technology, the researchers said.

The Columbia research team fired high-energy beams of helium ions at a planar region that is just below the surface of the crystalline material, yttrium iron garnet (YIG), to loosen it from its substrate, gadolinium gallium garnet. They then applied chemicals to the region to cut the bonds entirely, slicing off an ultra-thin sheet of magnetic material from a single crystal. The sample was then lifted off and bonded to a high-quality semiconductor.

The goal of this effort is to make devices that allow light to go in only one direction on a fiber optic microchip, Professor Osgood said. Light guides etched into the magnetic crystal, when exposed to a magnetic field, allow the light to travel in one direction only, making the light guide an effective routing device in an optic fiber network.

The work is the result of a collaboration between Columbia and the University of Minnesota to create integrated photonic devices for use in fiber optic communications systems. The collaboration is funded by the federal Advanced Research Projects Agency.

This document is available at Working press may receive science and technology press releases via e-mail by sending a message to



Columbia University

Related Electronics Articles from Brightsurf:

Artificial materials for more efficient electronics
The discovery by a team of the University of Geneva of an unprecedented physical effect in a new artificial material marks a significant milestone in the lengthy process of developing ''made-to-order'' materials and more energy-efficient electronics.

The new tattoo: Drawing electronics on skin
One day, people could monitor their own health conditions by simply picking up a pencil and drawing a bioelectronic device on their skin.

Lighting the way to porous electronics and sensors
Researchers from Osaka University have created porous titanium dioxide ceramic thin films, at high temperatures and room temperature.

The ink of the future in printed electronics
A research group led by Simone Fabiano at the Laboratory of Organic Electronics, Linköping University, has created an organic material with superb conductivity that doesn't need to be doped.

Integrating electronics onto physical prototypes
MIT researchers have invented a way to integrate 'breadboards' -- flat platforms widely used for electronics prototyping -- directly onto physical products.

Something from nothing: Using waste heat to power electronics
Researchers from the University of Tsukuba developed an improved thermocell design to convert heat into electricity.

Electronics at the speed of light
A European team of researchers including physicists from the University of Konstanz has found a way of transporting electrons at times below the femtosecond range by manipulating them with light.

Electronics integrated to the muscle via 'Kirigami'
A research team in the Department of Electrical and Electronic Information Engineering and the Electronics-Inspired Interdisciplinary Research Institute (EIIRIS) at Toyohashi University of Technology has developed a donut-shaped kirigami device for electromyography (EMG) recordings.

Creating 2D heterostructures for future electronics
New research integrates nanomaterials into heterostructures, an important step toward creating nanoelectronics.

Researchers report a new way to produce curvy electronics
Contact lenses that can monitor your health as well as correct your eyesight aren't science fiction, but an efficient manufacturing method has remained elusive.

Read More: Electronics News and Electronics Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to