World-record micrometer-sized converter of electrical into optical signals

Feb 18, 2014
World-record micrometer-sized converter of electrical into optical signals
Due to the voltage applied, a beam of light (top left) is modulated by the digital bits (bottom right) of the converter (yellow). An electrical signal is converted into an optical signal. Credit: A. Melikyan/KIT

Thanks to optical signals, mails and data can be transmitted rapidly around the globe. But also exchange of digital information between electronic chips may be accelerated and energy efficiency might be increased by using optical signals. However, this would require simple methods to switch from electrical to optical signals. In the Nature Photonics magazine, researchers now present a device of 29 µm in length, which converts signals at a rate of about 40 gigabits per second. It is the most compact high-speed phase modulator in the world.

"Conversion of electrical into happens closer to the processor," Juerg Leuthold says. He coordinated the research project at the Karlsruhe Institute of Technology and has meanwhile moved to the ETH Zurich. "As a result, speed gains are achieved and conduction losses can be prevented. This might reduce energy consumption of the growing ."

The electro-optical converter consists of two parallel gold electrodes of about 29 µm in length, which is one third of the diameter of a human hair. The electrodes are separated by a gap of about one tenth of a micrometer in width. The voltage applied to the electrodes is synchronized with the digital data. The gap is filled with an electro-optical polymer, whose refraction index changes as a function of the applied voltage. "A continuous beam of light from the silicon waveguide excites electromagnetic surface waves, so-called surface plasmons (SP), in the gap," Argishti Melikyan, KIT, first author of the publication, explains. "As a result of the voltage applied to the polymer, the phase of the SP is modulated. At the end of the device, the modulated SP enter the exit silicon waveguide in the form of a modulated beam of light. In this way, the data bits are encoded in the phase of the light."

Their recent results revealed that the electro-optic modulator reliably converts data flows of about 40 gigabits per second. It uses the infrared light of 1480 – 1600 nanometers in wavelength usually encountered in the broadband glass fiber network. Even temperatures of up to 85°C do not cause any operation failures. The presented device is the most compact high-speed phase modulator in the world. It can be produced by well-established CMOS fabrication processes. Integration into current chip architectures is hence possible. "The device combines many advantages of other systems, such as a high modulation speed, compact design, and . In the future, plasmonic devices might be used for signal processing in the terahertz range," says Christian Koos, spokesperson of KIT's Helmholtz International Research School of Teratronics (HIRST), which focuses on merging photonic and electronic techniques for high-speed signal processing. "Hundreds of plasmonic modulators might fit on a chip and data rates in the range of terabits per second might be reached."

Presently, information and communication systems consume about 10 percent of the electricity in Germany. This includes computers and smartphones of individual users as well as servers at large computing centers. As data traffic grows exponentially, new approaches are required to increasing the capacity of such systems and reducing their at the same time. Plasmonic components might be of decisive importance in this respect.

Explore further: Controlling light with light

More information: "High-speed plasmonic phase modulators," A. Melikyan, L. Alloatti, A. Muslija, D. Hillerkuss, P. C. Schindler, J. Li, R. Palmer, D. Korn, S. Muehlbrandt, D. Van Thourhout, B. Chen, R. Dinu, M. Sommer, C. Koos, M. Kohl, W. Freude, and J. Leuthold, Nature Photonics AOP, DOI: 10.1038/NPHOTON.2014.9

add to favorites email to friend print save as pdf

Related Stories

Controlling light with light

Jan 10, 2014

A new approach to control light with light without the need for optical nonlinearity: Nanoparticle auto-oscillations in a subwavelength plasmonic V-groove waveguide induced by a control light can be used for the periodic ...

World record: Wireless data transmission at 100 Gbit/s

Oct 14, 2013

Extension of cable-based telecommunication networks requires high investments in both conurbations and rural areas. Broadband data transmission via radio relay links might help to cross rivers, motorways ...

Graphene photodetector integrated into computer chip

Sep 16, 2013

The novel material graphene and its technological applications are studied at the Vienna University of Technology. Now scientists succeeded in combining graphene light detectors with semiconductor chips.

Recommended for you

Researchers develop powerful, silicon-based laser

Sep 29, 2014

A silicon-based laser that lases up to a record 111°C, with a threshold current density of 200 A/cm2 and an output power exceeding 100 mW at room temperature, has been demonstrated by collaborating researcher ...

Predicting landslides with light

Sep 29, 2014

Optical fiber sensors are used around the world to monitor the condition of difficult-to-access segments of infrastructure—such as the underbellies of bridges, the exterior walls of tunnels, the feet of dams, long pipelines ...

Studies in laser physics help understand rogue waves

Sep 29, 2014

(Phys.org) —University of Auckland physicist Dr Miro Erkintalo is part of an international team investigating how lasers and optical fibres can be used to understand freakishly large waves on the ocean.

User comments : 0