IBM (NYSE: IBM) has been active in the graphene field from the earliest days of its emergence as a material like no other. The first integrated circuit, showcased by the company at the end of 2011, has now been eclipsed by their development of the science of the material’s photonic properties.
According to IBM, researchers may be able to create terahertz photonics modulators for optical connections, an advance that paves the way for mid- and far-infrared photonic devices, including detectors, modulators, and three-dimensional metamaterials.
The breakthrough with graphene is all the more important because there are currently few options available to scientists wishing to harness the power of light in terahertz waves. The “exceptional optical properties” of graphene, whose zero gap band width absorbs light from far-infrared to ultraviolet, has allowed IBM’s scientists to explore these new possibilities.
“In addition to its good electrical properties, graphene also has exceptional optical properties. In particular, it absorbs light from the far-infrared to the ultra-violet,” said IBM Fellow Phaedon Avouris. “The terahertz range was of particular interest to IBM, because these frequencies can penetrate paper, wood and other solid objects for security applications. Unfortunately, today there are very few ways of manipulating terahertz waves such as polarizing and filtering it, but because graphene operates well at terahertz frequencies we have concentrating on creating these types of devices.”
The IBM researchers have improved on results obtained with single layer graphene by creating a super-lattice of multilayered graphene that allows a resonant frequency suitable for photonics. Tuning the graphene for the terahertz band became the focus for the IBM team because this wavelength of light is capable of penetrating paper, wood and other solid objects for security applications.
Implemented by laying down wafer scale alternating layers of graphene and a polymer insulator, then patterning them into microdisks, IBM demonstrated that these graphene/insulator superlattices shielded 97.5% of electromagnetic radiation at frequencies below 1.2 terahertz.
According to IBM, the researchers are working on tuning the graphene superlattices for the infrared frequencies used in current optical communications equipment.