Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nano-optics: Getting the most out of tiny lasers

07.07.2014

An off-center waveguide enables light to be efficiently extracted from nanoscale lasers.

Semiconductor optical devices are becoming increasingly commonplace. For example, light-emitting diodes, as they become more power efficient, are rapidly replacing conventional light bulbs. Lasers too are now found in every barcode scanner and compact-disc reader.


Computer simulations show that efficient light extraction from a nanoring plasmonic laser can occur when a waveguide is connected flush with one edge of the device. Modified from Ref. 1 and licensed under CC BY-NC 3.0

Copyright : 2014 C. Lee et al.

When designing these devices, a crucial consideration is how best to get the light generated within the solid material out into the real world. Chee-Wei Lee at the A*STAR Data Storage Institute, Singapore, and international colleagues have now proposed a light-extraction scheme that is capable of transferring over half the light created by a submicrometer-scale laser into a waveguide(1).

Plasmonic lasers are the smallest lasers created to date — they can even be smaller than the wavelength of the light they emit. This counterintuitive property results from plasmons, which are hybrid electron–light particles created by coupling light with electrons in a metal.

Lee and his team considered the simplest plasmonic laser: a ring of a light-emitting semiconductor coated with a thin silver layer. Light can travel round and round inside the ring, which provides the optical cavity required in most laser devices.

What is more, this tiny laser can be bonded onto a silicon substrate to make it compatible with compact photonics-on-a-chip technology. Lee and his team used computer simulations to demonstrate that high extraction efficiency is obtained when a waveguide (a light-carrying submicrometer-wide semiconductor strip) is directly connected to the side of the laser.

The team used a numerical simulation technique called finite-difference time-domain to study the performance of waveguides of different widths connected at different points on the laser. Their models revealed that the optimal structure is an asymmetric one.

When the extraction waveguide is displaced from the center of the ring — so that the waveguide is flush with the edge of the cavity — it produces a peak out-coupling efficiency of 56 per cent (see image). “Our scheme, based on directly joining a waveguide, enhances light extraction by splitting the plasmon mode,” explains Lee.

Scientists have previously extracted light from plasmonic lasers by running a waveguide extremely close to, but not touching, the cavity ring. Light can leak across the gap between the laser and the waveguide through an effect called evanescent coupling.

But this approach requires precise control over the gap size and the optical properties of the material in the gap. The method developed by the team, however, can be implemented using much simpler device fabrication. “We are now in the process of actually realizing such a device,” says Lee.

Reference

1. Lee, C.-W., Singh, G. & Wang, Q. Light extraction — a practical consideration for a plasmonic nano-ring laser. Nanoscale 5, 10835–10838 (2013). 

Associated links

Lee Swee Heng | Research SEA News
Further information:
http://www.researchsea.com

More articles from Process Engineering:

nachricht New process for cell transfection in high-throughput screening
21.03.2016 | Laser Zentrum Hannover e.V.

nachricht Sustainable products: Fraunhofer LBF investigates recycling of halogen-free flame retardant
17.02.2016 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Streamlining accelerated computing for industry

PyFR code combines high accuracy with flexibility to resolve unsteady turbulence problems

Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...

Im Focus: X-ray optics on a chip

Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.

In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...

Im Focus: Piggyback battery for microchips: TU Graz researchers develop new battery concept

Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.

Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...

Im Focus: UCI physicists confirm possible discovery of fifth force of nature

Light particle could be key to understanding dark matter in universe

Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...

Im Focus: Wi-fi from lasers

White light from lasers demonstrates data speeds of up to 2 GB/s

A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The energy transition is not possible without Geotechnics

25.08.2016 | Event News

New Ideas for the Shipping Industry

24.08.2016 | Event News

A week of excellence: 22 of the world’s best computer scientists and mathematicians in Heidelberg

12.08.2016 | Event News

 
Latest News

Symmetry crucial for building key biomaterial collagen in the lab

26.08.2016 | Health and Medicine

Volcanic eruption masked acceleration in sea level rise

26.08.2016 | Earth Sciences

Moth takes advantage of defensive compounds in Physalis fruits

26.08.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>