Ed: This was published in the Okanagan Phoenix on Oct 7th, 2009
Last week, I interviewed a UBC-O Engineering professor, Dr. Kenneth Chau, about his recent research. Dr. Chau joined the school of Engineering in January, from the National Institute of Standards and Technology (NIST) in the USA. His particular specialty is nanotechnology. Nanotechnology is a field dealing with technology and objects that are at the nanometer(nm)-scale size. To put it in perspective, a nanometer, which is 1 billionth(1000 million) of a meter, is 1/1000th the width of a human hair and the wavelength of visible light goes from 400-700 nm.

Dr. Chau recently made a significant advancement in the field of nanotechnology, where he demonstrated that light could actually pull a nano-scale object, rather than just push. The implications are very important, both for the field, and eventually for the production of military, scientific, and consumer products.

The kind of materials that Dr. Chau and others in his field work with, named ‘metamaterials’, offer many benefits to military, scientific, and consumer fields. For the military, such materials and devices can create new metal alloys, with potential unique properties, like extreme heat resistance or superior strength. On top of that, metamaterials offer the possibilities of perfect lenses, or perfectly reflective mirrors. In the more futuristic list of possibilities, it is believed that this field of nanotechnology will eventually allow us to build an invisibility cloak, or even optical computers, but both such inventions are far from being created.

All objects can be characterized by a refractive index, or an index of refraction as it is also called. This is the degree to which light is slowed down within the medium. As well, when light crosses the boundary between two mediums with different refractive indexes, light bends. Microscopes and lenses work by bending light in useful ways. All natural mediums have a positive refractive index, meaning that light is slowed down within the medium. However, some metamaterials have a property known as a negative refractive index, where light is bent in the opposite direction than in materials with a positive refractive index.

This is where the radiation pressure of light comes into play. Light has momentum, like any object that is in motion. However, light has a very small momentum, and can only affect small particles. The radiation pressure effect of light is why comets’ tails are always pointed away from the sun; the charged particles are pushed away by the radiation pressure of light. Picture a fire hose being pointed at you. The pressure of the hose pushes you away.

When the radiation pressure of light is combined with a negative index of refraction, Dr. Chau, proved, via experiment, that light can actually exert a pull force, in addition to pushing around particles. It is like some method of making the fire hose pull you, instead of pushing you away. If researchers can construct objects with arbitrary optical properties, then they can manipulate light in arbitrary ways, leading to all of the innovations listed previously, and many more not imagined yet. We have things, previously thought to be only in the realm of science fiction, happening in labs every day, around the world, and even on our campus.

Currently, the Chau Research group Dr. Chau is working on several exciting projects, and require talented and capable students with diverse backgrounds. One project Dr. Chau is involved in is the construction of a computer cluster, also known as a supercomputer, for simulating complex physical phenomenon. Another is a project to build a sensor, capable of detecting contaminants in water, by using spectroscopic analysis of light that comes out of properly formed droplets of water. One possible use for this optical sensor is to detect vanishingly small amounts of impurities in water.