+44 (0)24 7671 8970
More publications     •     Advertise with us     •     Contact us
 
Loading...
News Article

US team creates first terahertza polarisation optical switch

News

Nanotechnology experts at Sandia use photonics to switch thin film device from dark to transparent in trillionths of a second

A Sandia National Laboratories-led team has for the first time used photonics rather than electronics to switch a nanometer-thick thin film device from completely dark to completely transparent, or light, at a speed of trillionths of a second.

The team led by principal investigator Igal Brener published a Nature Photonics paper this spring with collaborators at North Carolina State University. The paper describes work on optical information processing, such as switching or light polarisation control using light as the control beam, at terahertz speeds, a rate much faster than what is achievable today by electronic means, and a smaller overall device size than other all-optical switching technologies.

Electrons spinning around inside devices like those used in telecommunications equipment have a speed limit due to a slow charging rate and poor heat dissipation, so if significantly faster operation is the goal, electrons might have to give way to photons.

To use photons effectively, the technique requires a device that goes from completely light to completely dark at terahertz speeds. In the past, researchers couldn't get the necessary contrast change from an optical switch at the speed needed in a small device. Previous attempts were more like dimming a light than turning it off, or required light to travel a long distance.

The breakthrough shows it's possible to do high contrast all-optical switching in a very thin device, in which light intensity or polarisation is switched optically, said Yuanmu Yang, a former Sandia Labs postdoctoral employee who worked at the Center for Integrated Nanotechnologies, a Department of Energy user facility jointly operated by Sandia and Los Alamos national laboratories. The work was done at CINT.

"Instead of switching a current on and off, the goal would be to switch light on and off at rates much faster than what is achievable today," Yang said.

Faster information processing

A very rapid and compact switching platform opens up a new way to investigate fundamental physics problems. "A lot of physical processes actually occur at a very fast speed, at a rate of a few terahertz," Yang said. "Having this tool lets us study the dynamics of physical processes like molecular rotation and magnetic spin. It's important for research and for moving knowledge further along."

It also could act as a rapid polarisation switch -- polarisation changes the characteristics of light -- that could be used in biological imaging or chemical spectroscopy, Brener said. "Sometimes you do measurements that require changing the polarisation of light at a very fast rate. Our device can work like that too. It's either an absolute switch that turns on and off or a polarisation switch that just switches the polarisation of light."

Ultrafast information processing "matters in computing, telecommunications, signal processing, image processing and in chemistry and biology experiments where you want very fast switching," Brener said. "There are some laser-based imaging techniques that will benefit from having fast switching too."

The team's discovery arose from research funded by the Energy Department's Basic Energy Sciences, Division of Materials Sciences and Engineering, that, among other things, lets Sandia study light-matter interaction and different concepts in nanophotonics.

"This is an example where it just grew organically from fundamental research into something that has an amazing performance," Brener said. "Also, we were lucky that we had a collaboration with North Carolina State University. They had the material and we realized that we could use it for this purpose. It wasn't driven by an applied project; it was the other way around."

The technique uses two laser beams, one carrying the information and the second switching the device on and off. The switching beam uses photons to heat up electrons inside semiconductors to temperatures of a few thousand degrees Fahrenheit, which doesn't cause the sample to get that hot but dramatically changes the material's optical properties. The material also relaxes at terahertz speeds, in a few hundred femtoseconds or in less than one trillionth of a second. "So we can switch this material on and off at a rate of a few trillion times per second," Yang said.

Sandia researchers turn the optical switch on and off by creating a plasmonic cavity, which confines light within a few tens of nanometers, and significantly boosts light-matter interaction. By using a special plasmonic material, doped cadmium oxide from North Carolina State, they built a high-quality plasmonic cavity. Heating up electrons in the doped cadmium oxide drastically modifies the opto-electrical properties of the plasmonics cavity, modulating the intensity of the reflected light.

Traditional plasmonic materials like gold or silver are barely sensitive to the optical control beam. Shining a beam onto them doesn't change their properties from light to dark or vice versa. The optical control beam, however, alters the doped cadmium oxide cavity very rapidly, controlling its optical properties like an on-off switch.

The next step is figuring out how to use electrical pulses rather than optical pulses to activate the switch, since an all-optical approach still requires large equipment, Brener said. He estimates the work could take three to five years. "For practical purposes, you need to miniaturize and do this electrically," he said.

EMCORE announces integration of PICs into its products
Scottish photonics consortium wins £4.7m in UKRI funding
Yuanjie Semiconductor to supply lasers to POET
Fraunhofer IPMS announces government funding for quantum photonic chip
POET Technologies partners with Yuanjie Semiconductor Technology
SiLC announces silicon photonics systems for machine vision
Scientists develop novel optical modulators for integrated photonics
Scientists report integrated photodiodes on TFLN
Coherent wins award for innovative photonics product
FBH to present quantum technology developments at EQTC 2023
Skorpios and FormericaOE demonstrate PICs in 800G optical transceivers
EFFECT Photonics verifies fully integrated InP PIC
NASA awards grant for silicon photonics project
OpenLight and Spark Photonics partner on PIC design services
DustPhotonics announces 800G chip for hyperscale data centres and AI
Lightwave Logic Receives Industry Innovation Award
Imec announces SiGe BiCMOS optical receiver
SiFotonics announces silicon photonics 800G LPO solutions
Rockley Photonics progresses noninvasive biomarker monitoring
MantiSpectra secures €4 million for miniaturised spectrometers
Sivers to demo next-gen laser arrays at ECOC 2023
ASMPT AMICRA and Teramount collaborate on silicon photonics packaging
Quantum Computing Inc. selects Arizona site for photonic chip foundry
German government to fund ams OSRAM optoelectronic semiconductor development
Luceda Photonics introduces new PIC design software
Vodafone explores silicon photonics for future mobile networks
Coherent introduces 1200 mW pump laser module
Photonics startups invited to apply to Luminate NY accelerator
New tool could improve lithography for smaller, faster chips
InP-based lasers surpass 2.2 mm
Indie Semiconductor buys Exalos AG
New technique controls direction and wavelength of emitted heat

×
Search the news archive

To close this popup you can press escape or click the close icon.
Logo
×
Logo
×
Register - Step 1

You may choose to subscribe to the PIC Magazine, the PIC Newsletter, or both. You may also request additional information if required, before submitting your application.


Please subscribe me to:

 

You chose the industry type of "Other"

Please enter the industry that you work in:
Please enter the industry that you work in: