Frequency–tunable terahertz metamaterials

DOI: 10.1038/nphoton.2008.52

The ability to use light to tune the frequency at which a material has a resonant response to terahertz waves — waves that can pass through non–conducting objects opaque to visible light — is reported online this week in Nature Photonics. The result overcomes the limitations of designs demonstrated so far and could lead to a new breed of active, frequency–agile terahertz devices that are controlled by light.

Terahertz waves, rays of electromagnetic radiation that lie in the frequency range of from 300 GHz to 3 THz, bridge the worlds of electronics and photonics and are useful for performing unique tasks in the fields of imaging, spectroscopy and telecommunications. Despite the recent progress in terahertz generation and detection, the techniques for controlling and manipulating terahertz waves are still lagging behind.

Terahertz metamaterials — composed of a two-dimensional array of resonators that interact with electromagnetic radiation in different ways to natural materials — can help. Unfortunately, they usually have a response that is fixed by their geometry. The response cannot be adjusted or tuned, and a new sample has to be redesigned and fabricated if effects at other frequencies are desired

Hou–Tong Chen and co–workers report that by incorporating two strips of silicon into each metallic split-ring resonator, they can tune the frequency resonance of a metamaterial from 1.06 THz to 850 GHz — a tuning range of 20% — when the array is illuminated with pulses of near–infrared laser light. The achievement is anticipated to aid the development of a new host of frequency–agile devices for use in this exciting region of the electromagnetic spectrum.

Author contact:

Hou–Tong Chen (Los Alamos National Laboratory, Los Alamos, NM, USA)

Media contact

Tel: +1 505 665 7365; E-mail: chenht@lanl.gov

Other papers from Nature Photonics to be published online at the same time and with the same embargo:

Superconducting nanowire photon-number-resolving detector at telecommunication wavelengths

DOI: 10.1038/nphoton.2008.51