Subscribe free to our newsletters via your
. 24/7 Space News .


Subscribe free to our newsletters via your




















STELLAR CHEMISTRY
Researchers found an unconventional phase transition in photonic structures
by Staff Writers
St Petersburg, Russia (SPX) Jan 01, 2016


Lattice of plastic pipes filled with heated water was used to test the calculations. Image courtesy ITMO University. For a larger version of this image please go here.

A team of physicists from ITMO University, Ioffe Physical-Technical Institute and Australian National University have researched the phenomenon of phase transition between photonic crystals and metamaterials - two types of periodic structures capable of manipulating light in intricate ways.

The study helps to gain an insight into the fundamental properties of periodic structures and opens new possibilities for the design and creation of new electromagnetic materials. The results of the study were published in Nature Communications.

Both photonic crystals and metamaterials are artificial materials compiled of little components with different electromagnetic properties. They resemble actual crystals, although the basic component in these materials is much bigger that just an atom or molecule.

In physics, such materials are interesting due to their ability to effectively control the propagation of light. Photons in these materials can move in very unusual trajectories that are defined by the properties of the constituents that make up the periodic structure of the material.

Scientists from Russia and Australia decided to test how the optical properties of such materials would change if their parameters were gradually modified. As a model, the scientists used ? lattice of plastic cylinders filled with heated water.

When interacting with light, such a structure can generate two types of resonances: local Mie resonance, associated with each cylinder individually, and extended Bragg resonance that appears due to the interference of light scattered from all cylinders. If the refraction index of cylinders is high, then the structure is said to belong to metamaterials, while if it is low - to photonic crystals.

The refraction index and the distance between neighboring cylinders are the two main factors that determine the photonic properties of the material.

The researchers made calculations for 100 different values of the refraction index and 50 values of lattice constant - ranging from cases where cylinders touched each other to cases where the distance between the cylinders reached 100 radii of one cylinder.

As a result, 5 000 different photonic structures were investigated. Each was assigned its place in the classification. The interpretation of the data allowed researchers to build the phase diagram of transition from a photonic crystal to a metamaterial.

"Usually, when we talk about phase transition - an abrupt change in material properties - we imagine the conversion of something hard into something liquid or, for instance, the appearance of electric properties caused by changes in temperature or pressure. This is due to the fact that temperature and pressure define the structure of the material at the atomic level.

"We influence it indirectly, so to speak, just by changing the parameters of the environment," says Mikhail Rybin, first author of the study and senior researcher at the Department of Nanophotonics and Metamaterials of ITMO University and Ioffe Physical-Technical Institute.

"In case of photonic structures, we ourselves define the required properties of the material, choosing the mutual arrangement and refraction index of the structural elements - meta-atoms. This enables us to introduce the concept of phase diagram in sets of axes: geometrical size - refraction index. In our case, the periodic structure generates local negative magnetic response, which acts as a sign of a metamaterial. In other words, the structure converts from a photonic crystal to a metamaterial," adds Rybin.

To test the theoretical calculation, the researchers arranged a meta-crystal out of plastic pipes filled with heated water. The measurements were conducted in the microwave range. In experiments, the phase transition was achieved in two different ways.

The first was induced by altering the water temperature in the meta-crystal from 90 to 20 degrees Celsius, which influenced the refraction index of water. The second method consisted in changing the spacing between the pipes, that is, making the meta-crystal smaller. This method resembles the increasing of pressure in conventional phase transitions.

The measurements perfectly matched the theoretical predications, required to build a phase diagram. The work therefore has become the first attempt to imagine photonic crystals and metamaterials within the single system with a set of parameters.

This is important, because now researchers do not need special calculations to anticipate which materials should be used to produce structural elements, and how densely they should be packed to produce a metamaterial.

.


Related Links
ITMO University
Stellar Chemistry, The Universe And All Within It






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
STELLAR CHEMISTRY
Ringing in a new way to measure and modulate trapped light
Washington DC (SPX) Dec 25, 2015
Researchers working at the National Institute of Standards and Technology (NIST) have developed a novel way to noninvasively measure and map how and where trapped light vibrates within microscale optical resonators. The new technique not only makes for more accurate measurements but also allows scientists to fine-tune the trapped light's frequency by subtly altering the shape of the resona ... read more


STELLAR CHEMISTRY
Rare full moon on Christmas Day

LADEE Mission Shows Force of Meteoroid Strikes on Lunar Exosphere

XPRIZE verifies moon express launch contract, kicking off new space race

Gaia's sensors scan a lunar transit

STELLAR CHEMISTRY
NASA suspends March launch of InSight mission to Mars

University researchers test prototype spacesuits at Kennedy

Marshall: Advancing the technology for NASA's Journey to Mars

Opportunity positioned on steeper slopes for another Martian winter

STELLAR CHEMISTRY
Astronauts Tour Future White Room, Crew Access Tower

Celebrity chefs create gourmet delights for astronauts

15 in '15: NASA's Commercial Crew Program Moves Closer to Flight

Researchers Recall Work on First Rendezvous in Space

STELLAR CHEMISTRY
Agreement with Chinese Space Tech Lab Will Advance Exploration Goals

China launches new communication satellite

China's indigenous SatNav performing well after tests

China launches Yaogan-29 remote sensing satellite

STELLAR CHEMISTRY
Space Station Receives New Space Tool to Help Locate Ammonia Leaks

Two whacks is all it takes for spacewalk repair

Unscheduled spacewalk likely on Monday

NASA spacewalk to fix ISS rail car

STELLAR CHEMISTRY
45th Space Wing launches ORBCOMM; historically lands first stage booster

SpaceX rocket landing opens 'new door' to space travel

NASA orders second Boeing Crew Mission to ISS

ESA and Arianespace ink James Webb Space Telescope launch contract

STELLAR CHEMISTRY
Nearby star hosts closest alien planet in the 'habitable zone'

ALMA reveals planetary construction sites

Monster planet is 'dancing with the stars'

Exoplanets Water Mystery Solved

STELLAR CHEMISTRY
Nature's masonry: The first steps in how thin protein sheets form polyhedral shells

Move aside carbon: Boron nitride-reinforced materials are even stronger

Super strong, lightweight metal could build tomorrow's spacecraft

BAE Systems to provide radar support for U.S. Air Force




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 1995-2016 - 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. 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 All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.