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 Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>