Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Switching one light beam with another, Cornell provides a key component for photonic chips

28.10.2004


Cornell University researchers have demonstrated for the first time a device that allows one low-powered beam of light to switch another on and off on silicon, a key component for future "photonic" microchips in which light replaces electrons.



Photonics on silicon has been suggested since the 1970s, and previous light-beam switching devices on silicon have been demonstrated, but they were excessively large (by microchip standards) or have required that the beam of light that does the switching be very high-powered. The approach developed by Michal Lipson, Cornell assistant professor of electrical and computer engineering, confines the beam to be switched in a circular resonator, greatly reducing the space required and allowing a very small change in refractive index to shift the material from transparent to opaque.

The advancement of nanoscale fabrication techniques in just the past few years has made it possible to overcome some of the traditional limitations of silicon photonics, Lipson said. Photonic circuits will find their first application in routing devices for fiber-optic communications, she suggests. At present, information that travels at the speed of light through optical fiber must be converted at the end into electrical signals that are processed on conventional electronic chips, then in many cases converted back into optical signals for retransmission, an extremely slow process. The all-optical switch makes it possible to route these signals without conversion.


The all-optical switch is described in the Oct. 28 issue of the journal Nature by Lipson and members of the Cornell Nanophotonics Research Group, which she directs. The researchers used the facilities of the Cornell NanoScale Facility to manufacture the devices on silicon chips. "It is highly desirable to use silicon -- the dominant material in the microelectronic industry -- as the platform for these photonic chips," they said in their paper. The group already has developed other components for silicon photonic chips, including straight and curved waveguides. One of the key components needed, however, is a way for one optical signal to switch another on or off.

Lipson’s optical switch is based on a ring resonator, a device already familiar to photonics researchers. When a ring-shaped waveguide is placed tangent to a straight one, photons traveling along the straight waveguide are diverted into the ring and travel around it many times, but only if they match the resonant frequency of the ring, which is determined by its circumference. For the reported experiments, the researchers created a ring 10 micrometers in diameter with a resonance wavelength of 1,555.5 nanometers, in the near infrared.

To turn the switch off, they pumped a second beam of light in the same wavelength range through the system. This light is absorbed by the silicon through a process known as two-photon absorption, creating many free electrons and "holes" (positively charged regions) in the material. This changes the refractive index and shifts the resonant frequency of the ring far enough that it will no longer resonate with the 1,555.5-nanometer signal. The process can theoretically take place in a few tens of picoseconds, the researchers said. A similar effect can be used in a straight waveguide, but it requires a fairly long distance. Because light travels many times around the ring, the scattering effect is enhanced and the signal can be controlled in a very small space.

For routing applications, Lipson said, a ring resonator coupled to two waveguides could be used. The second waveguide would receive a signal only when the resonator is switched on. She noted that there is very little loss of light in the ring, meaning that light coming into a routing device could be "recycled" and sent on its way with no additional amplification needed. Ring resonators also could be used as tunable filters, the researchers suggest, for example to separate the many wavelengths of light in multiplexed optical fiber communications systems.

The Nature paper is titled "All-optical switch on silicon: Controlling light with light on chip." Co-authors are Vilson Almeida, a former Cornell graduate student now in the Institute for Advanced Studies in the Technical Center of the Brazilian Air Force ; Carlos Barrios, former Cornell postdoctoral researcher and now a scientist in the Nanophotonics Technology Centre , Universidad Politénica de Valencia, Spain; and Roberto Panepucci, former Cornell research associate now an assistant professor at Florida International University.

Previous work on nanoscale optical waveguides and photonic coupling is described in a paper, "Overcoming the limitations of microelectronics using Si nanophotonics: solving the coupling, modulation and switching challenges," published in the Institute of Physics journal Nanotechnology , Aug. 2, 2004.

Bill Steele | EurekAlert!
Further information:
http://www.cornell.edu

More articles from Physics and Astronomy:

nachricht When fluid flows almost as fast as light -- with quantum rotation
22.06.2018 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

nachricht Thermal Radiation from Tiny Particles
22.06.2018 | Universität Greifswald

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>