It’s time for the third instalment of Photonics briefs. This week I’ll focus on a new report of a nano-photonic crystal, and feature a Canadian photonics researcher. Both articles are featured in the newest Advanced Online Publications of Nature Photonics.
First up, there’s a report of a new nanowire structure for generating two colours of light, and then distinguishing and guiding them (in different directions) through an integrated photonic crystal.
A photonic crystal is a physical array of a material with a periodic index of refraction. Typically the crystals are made in either 2 or 3 dimensions. The period of the material is typically comparable to the wavelength of the light meant to be controlled (so half a micron for visible). Photonic crystals are often used to control the direction and flow of light (as crystals can be designed to prevent the flow of certain wavelengths and gaps can be left to direct light through the crystal – like a channel).
The result of this group was to create a device which could be easily fabricated, and could efficiently couple light from the source to the crystal, from which it could be extracted to a fibre optic cable or put to other uses.
As can be seen in the image (from ref), the wire is situated in the middle of the device and is capable of generating two wavelenths of light. One frequency can make it through each crystal array on either side of the wire. This divides the light and provides the ability to extract one of two colours (or both) at the same time.
- Hong-Gyu Park, Carl J. Barrelet, Yonging Wu, Bozhi Tian, Fang Qian and Charled M. Lieber, “A wavelength-selective photonic-crystal waveguide coupled to a nanowire light source”, Nature Photonics ADVANCED ONLINE PUBLICATIONS, 7 September 2008.
The Maritimes of Canada (the provinces on the East coast) are not typically thought of in terms of groundbreaking research, yet at Dalhousie University Professor Kimberley Hall has been establishing an impressive optics lab over the past few years. And with a recent deal with Lockheed-Martin, Dr. Hall has her sights set high.
Dr. Hall’s research focuses on ultrafast spintronics, or using ultrafast lasers to probe the interactions of magnetic dipoles (the smallest unit of magnetism) with external forces. By understanding the processes involved with magnetic spin, and being able to control it, an entire new field of information processing could potentially be opened, based off of the spin states of electrons (spintronics), as opposed to the electric states (traditional electronics).
An advantage of spintronics is that spin states are inherently binary, or based on 1 and 0s (or in spin-terms, up and down). Whereas with electronics we typically relied on voltages, which could vary and make mistakes. Spintronics is an exciting field in the near future for physicists, and is something I’ll likely cover further in the future.
Dalhousie University is located in Halifax, Nova Scotia, and Dr. Hall is currently recruiting for new students and researchers.