Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Researchers bend light through waveguides in colloidal crystals

Researchers at the University of Illinois are the first to achieve optical waveguiding of near-infrared light through features embedded in self-assembled, three-dimensional photonic crystals. Applications for the optically active crystals include low-loss waveguides, low-threshold lasers and on-chip optical circuitry.

Key to the fabrication technique – which uses multi-photon polymerization and a laser scanning confocal microscope – is a self-assembled, colloidal material that exhibits a photonic band gap, said Paul Braun, a University Scholar and professor of materials science and engineering.

In previous work, reported in 2002, Braun’s research group was the first to show that through multi-photon polymerization they could embed a polymer feature inside a silicon dioxide, self-assembled colloidal crystal.

Now, in a paper accepted for publication in Nature Photonics, and posted on the journal’s Web site, Braun and his team demonstrate actual optical activity in waveguides and cavities created in their colloidal crystals.

“Taking our earlier work as a starting point, we built upon recent advances in theory and computation, improvements in materials growth techniques, and better colloidal crystallization capabilities to produce this new photonic material,” said Braun, who also is affiliated with the university’s Beckman Institute, Frederick Seitz Materials Research Laboratory, and Micro and Nanotechnology Laboratory.

To make their optically active devices, the researchers begin by assembling a colloidal crystal of uniform silica spheres that are 900 nanometers in diameter. After removing the solvent, the researchers fill the spaces between the spheres with a photoactive monomer. Then they shine laser light through a microscope and into the crystal, polymerizing the monomer at the desired locations.

Next, they remove the unpolymerized liquid, and then fill the structure with silicon. Finally, they etch away the silica spheres, leaving the desired optical features embedded in a three-dimensional photonic crystal.

“Using spheres 900 nanometers in diameter creates a band gap at 1.5 microns, which is the wavelength used by the telecommunications industry for transmissions through fiber-optical cables,” Braun said. “Creating these waveguides by coupling colloidal assembly and multi-photon polymerization is simpler and less expensive than conventional fabrication techniques, especially for large-area photonic crystals.”

With Braun, co-authors of the paper are Stephanie A. Rinne, a postdoctoral fellow at the Beckman Institute, and Florencio García-Santamaría, a postdoctoral research associate in the department of materials science and engineering.

The work was funded by the U.S. Army Research Office, National Science Foundation and the U.S. Department of Energy.

To reach Paul Braun, call 217-244-7293; e-mail:

James E. Kloeppel | University of Illinois
Further information:

More articles from Physics and Astronomy:

nachricht 'Frequency combs' ID chemicals within the mid-infrared spectral region
16.03.2018 | American Institute of Physics

nachricht Fraunhofer HHI have developed a novel single-polarization Kramers-Kronig receiver scheme
16.03.2018 | Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, HHI

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: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Development and Fast Analysis of 3D Printed HF Components

19.03.2018 | Trade Fair News

In monogamous species, a compatible partner is more important than an ornamented one

19.03.2018 | Life Sciences

Signaling Pathways to the Nucleus

19.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>