Graphene based terahertz absorbers

Graphene based terahertz absorbers
Printable graphene inks enable ultrafast lasers in the terahertz range. Credit: Graphene Flagship

Graphene Flagship researches from CNR-Istituto Nanoscienze, Italy and the University of Cambridge, UK have shown that it is possible to create a terahertz saturable absorber using graphene produced by liquid phase exfoliation and deposited by transfer coating and ink jet printing. The paper, published in Nature Communications, reports a terahertz saturable absorber with an order of magnitude higher absorption modulation than other devices produced to date.

A saturable absorber decreases its absorption of light in the terahertz range (far infrared) with increasing light intensity and has great potential for the development of terahertz lasers, with applications in spectroscopy and imaging. These high-modulation, mode-locked lasers open up many prospects in applications where short time scale excitation of specific transitions are important, such as time-resolved spectroscopy of gasses and molecules, quantum information or ultra-high speed communication.

"We started working on saturable terahertz absorbers to solve the problem of producing a miniaturized mode-locked terahertz with thin and flexible integrated components that also had good modulation," said Graphene Flagship researcher Miriam Vitiello from CNR-Istituto Nanoscienze in Italy.

Graphene is a promising saturable absorber as it has intrinsic broadband operations and ultrafast recovery time along with an ease of fabrication and integration, as first demonstrated in ultra-fast infra-red lasers by Flagship partner University of Cambridge. In the terahertz range, the present paper exploits graphene produced by liquid phase exfoliation, a method ideally suited to mass production, to prepare inks, easily deposited by transfer coating or

"It was important to us to use a type of graphene that could be integrated into the laser system with flexibility and control" said Vitiello "Ink jet printing along with transfer coating achieved that."

Using mode-locked lasers to produce ultra fast pulses in the terahertz range can have interesting and exciting uses. "These devices could have applications in medical diagnostics when time of flight topography is of importance – you could see a tumour inside a tissue," said Vitiello.

Frank Koppens, of the Institute of Photonic Sciences in Spain, is the leader of the Graphene Flagship's Photonics and Optoelectronics Work Package, which focuses on developing graphene-based technologies for imaging and sensing, data transfer and other photonics applications. "This is a new discovery with immediate impact on applications. Clearly, this is a case where graphene beats existing materials in terms of efficiency, scalability, compactness and speed," he said.

Andrea C. Ferrari, Science and Technology Officer of the Graphene Flagship, and Chair of its Management Panel added "It is an important milestone to have demonstrated that easily produced and printable graphene inks can also serve to enable ultrafast lasers in the . Since the Flagship's inception, a variety of lasers have been made covering the visible to IR spectral range, but now the important THz range, with in security and medical diagnostic, is finally made accessible by , starting yet another possible application field."


Explore further

Graphene and terahertz waves could lead the way to future communication

More information: Vezio Bianchi et al. Terahertz saturable absorbers from liquid phase exfoliation of graphite, Nature Communications (2017). DOI: 10.1038/ncomms15763
Journal information: Nature Communications

Provided by Graphene Flagship
Citation: Graphene based terahertz absorbers (2017, September 12) retrieved 18 September 2019 from https://phys.org/news/2017-09-graphene-based-terahertz-absorbers.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
5 shares

Feedback to editors

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more