Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The direct approach to microcavities

09.05.2014

A robust micrometer-scale structure for trapping light enhances optical interactions in advanced photonic devices

Trapping light into a small volume is a useful way of amplifying optical effects. Optical cavities, for example, can enhance the interaction between light and matter. Incorporating these tiny structures into actual devices is difficult however, because they are easily broken or can become optically misaligned.


A gold grating at the end of an optical fiber couples light into a spherical microcavity, shown here as a purple sphere. The red arrows show the light bent by the grating, which is then coupled to the whispering-gallery mode (red circle). Concentrating light in compact structures is important for advancing photonics.

Copyright : 2014 A*STAR Singapore Institute of Manufacturing Technology

Xia Yu at the A*STAR Singapore Institute of Manufacturing Technology and co-workers have now developed an optical-fiber-based structure that harnesses the potential of light trapped in a microcavity. The novel design also provides a robust route to advanced devices for filtering and sensing light1.

Yu and colleagues melted silica glass to form a sphere with a diameter of 182 micrometers. They then patterned the end of an optical fiber with a gold grating and held it close to the microsphere. The grating coupled light propagating along the fiber into the sphere (see image). Light with the right wavelength traveled around in circles within the sphere, trapped by the smooth silica–air interface. This confined light is known as a whispering-gallery resonant mode.

The A*STAR team investigated the properties of their structure by measuring the amount of light at each wavelength that managed to escape from the cavity back into the fiber. The typical wavelength-dependent response of a microsphere is a sharp, symmetric peak centered on the resonant wavelength of the cavity.

Instead, the researchers observed an asymmetric spectral peak, which they recognized as a clear signature of the so-called Fano effect, indicating strong interaction or interference between the whispering-gallery mode and the light in the fiber directly reflected back from the grating.

“This interfering effect makes Fano resonances especially sensitive to changes in either of the participating systems: a slight perturbation results in dramatic alteration in the optical characteristics,” says Yu. “An obvious application of Fano resonance is for use in ultra-sensitive detection.”

In previous investigations of the optical Fano effect, researchers inserted (and extracted) light into the cavity through the side of an optical fiber — an approach that proved unstable and inefficient. The method used by Yu and colleagues of directly inserting light into the cavity through the end of the fiber proved far more robust, making the technology a plausible platform for cheap and compact optical-resonator-based photonic devices.

Another possible application for the technology is as an optical switch. “A good switching device must be fast,” explains Yu. “Therefore, the next step in our research will be to attempt to control the speed of the whispering-gallery mode Fano resonance.”


The A*STAR-affiliated researchers contributing to this research are from the Singapore Institute of Manufacturing Technology

Associated links

Journal information

Zhou, Y., Zhu, D., Yu, X., Ding, W. & Luan, F. Fano resonances in metallic grating coupled whispering gallery mode resonator. Applied Physics Letters 103, 151108 (2013)

A*STAR Research | Research SEA News
Further information:
http://www.a-star.edu.sg
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>