Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



TECH SPACE
Exciting breakthrough in 2-D lasers
by Staff Writers
Berkeley CA (SPX) Oct 22, 2015


In this 2-D excitonic laser, the sandwiching of a monolayer of tungsten disulfide between the two dielectric layers of a microdisk resonator creates the potential for ultralow-threshold lasing. Image courtesy Xiang Zhang, Berkeley Lab. For a larger version of this image please go here.

An important step towards next-generation ultra-compact photonic and optoelectronic devices has been taken with the realization of a two-dimensional excitonic laser. Scientists with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) embedded a monolayer of tungsten disulfide into a special microdisk resonator to achieve bright excitonic lasing at visible light wavelengths.

"Our observation of high-quality excitonic lasing from a single molecular layer of tungsten disulfide marks a major step towards two-dimensional on-chip optoelectronics for high-performance optical communication and computing applications," says Xiang Zhang, director of Berkeley Lab's Materials Sciences Division and the leader of this study.

Zhang, who also holds the Ernest S. Kuh Endowed Chair at the University of California (UC) Berkeley and is a member of the Kavli Energy NanoSciences Institute at Berkeley (Kavli ENSI), is the corresponding author of a paper describing this research in the journal Nature Photonics. The paper is titled "Monolayer excitonic laser." The lead authors are Yu Ye and Zi Jing Wong, members of Zhang's research group, plus Xiufang Lu, Xingjie Ni, Hanyu Zhu, Xianhui Chen and Yuan Wang.

Among the most talked about class of materials in the world of nanotechnology today are two-dimensional (2D) transition metal dichalcogenides (TMDCs). These 2D semiconductors offer superior energy efficiency and conduct electrons much faster than silicon. Furthermore, unlike graphene, the other highly touted 2D semiconductor, TMDCs have natural bandgaps that allow their electrical conductance to be switched "on and off," making them more device-ready than graphene.

Tungsten disulfide in a single molecular layer is widely regarded as one of the most promising TMDCs for photonic and optoelectronic applications. However, until now, coherent light emission, or lasing, considered essential for "on-chip" applications, had not been realized in this material.

"TMDCs have shown exceptionally strong light-matter interactions that result in extraordinary excitonic properties," Zhang says.

"These properties arise from the quantum confinement and crystal symmetry effect on the electronic band structure as the material is thinned down to a monolayer. However, for 2D lasing, the design and fabrication of microcavities that provide a high optical mode confinement factor and high quality, or Q, factor is required."

In a previous study, Zhang and his research group had developed a "whispering gallery microcavity" for plasmons, electromagnetic waves that roll across the surfaces of metals. Based on the principle behind whispering galleries - where words spoken softly beneath a domed ceiling can be clearly heard on the opposite side of the chamber - this micro-sized metallic cavity for plasmons strengthened and greatly enhanced the Q factor of light emissions.

In this new study, Zhang and his group were able to adapt this microcavity technology from plasmons to excitons - photoexcited electrons/hole pairs within a single layer of molecules.

"For our excitonic laser, we dropped the metal coating and designed a microdisk resonator that supports a dielectric whispering gallery mode rather than a plasmonic mode, and gives us a high Q factor with low power consumption," says co-lead author Ye. "When a monolayer of tungsten disulfide - serving as the gain medium - is sandwiched between the two dielectric layers of the resonator, we create the potential for ultralow-threshold lasing."

In addition to its photonic and optoelectronic applications, this 2D excitonic laser technology also has potential for valleytronic applications, in which digital information is encoded in the spin and momentum of an electron moving through a crystal lattice as a wave with energy peaks and valleys. Valleytronics is seen as an alternative to spintronics for quantum computing.

"TMDCs such as tungsten disulfide provide unique access to spin and valley degrees of freedom," says co-lead author Wong.

"Selective excitation of the carrier population in one set of two distinct valleys can further lead to lasing in the confined valley, paving the way for easily-tunable circularly polarized lasers. The demand for circularly polarized coherent light sources is high, ranging from three-dimensional displays to effective spin sources in spintronics, and information carriers in quantum computation."


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Lawrence Berkeley National Laboratory
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TECH SPACE
Mode control for square microresonator lasers suitable for integration
Beijing, China (SPX) Oct 15, 2015
Totally internal confined whispering-gallery modes can have high Q factors in wavelength scale optical microresonators, such as microspheres and two-dimensional microdisk resonators. Square optical resonators can also support high Q whispering-gallery modes, suitable to realize unidirectional microlasers. Microsquare lasers have a larger overlap between the mode field pattern and injected ... read more


TECH SPACE
Europe-Russia Lunar mission will make them friends again

Mound near lunar south pole formed by unique volcanic process

Lunar Pox

Space startup confirms plans for robotic moon landings

TECH SPACE
Landing site recommended for ExoMars 2018

You too can learn to farm on Mars

The Martian Astrobiologist

Opportunity parked for solar panels to charge up for winter

TECH SPACE
Hold on to your hoverboard: 'Back to the Future' is now

Journaling: Astronauts chronicle missions

Brands eye big bucks with 'Back to the Future' nostalgia

Russian Cosmonauts Taste 160 Meals Ahead of Space Station Expedition

TECH SPACE
China aims to go deeper into space

Latest Mars film bespeaks potential of China-U.S. space cooperation

Exhibition on "father of Chinese rocketry" opens in U.S.

The First Meeting of the U.S.-China Space Dialogue

TECH SPACE
RSC Energia patented inflatable space module for ISS

Clearing the Space Fog on ISS

International Space Agencies Meet to Advance Space Exploration

Meet the International Docking Adapter

TECH SPACE
ORBCOMM Announces Launch Window For Second OG2 Mission

10th Anniversary of the Final Titan

China puts new communication satellite into orbit for HK company

ISRO to Launch 6 Singapore Satellites in December

TECH SPACE
Cosmic 'Death Star' is destroying a planet

Most earth-like worlds have yet to be born, according to theoretical study

Airbus DS ready to start testing exoplanet tracker CHEOPS

Hubble Telescope Spots Mysterious Space Objects

TECH SPACE
U.S. Air Force long-range radar systems reach full operational capability

A 'hot' new development for ultracold magnetic sensors

Mother-of-pearl's genesis identified in mineral's transformation

Exciting breakthrough in 2-D lasers




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement