The bright future of light technology and photonics

What do surgical instruments, high-speed computer communications, low-energy Christmas tree lights, pollution measurements and improved education in the developing world all have in common? They all either rely upon or could be improved by advanced forms of light.

Our lives have been transformed by the use of light in the same way that they were transformed during the age of electronics.

"Today you could replace electronics with the word 'photonics in terms of its impact on industry and our lives in a modern world," says NUI Galway's Prof Martin Leahy. We have reached the limit of what we can do with electronics. You have to bring improvements using light."

The UN has designated 2015 as the Unesco International Year of Light. President Michael D Higgins is serving as Ireland's patron for the year, and Prof Leahy, professor of applied physics at Galway, has been selected to lead the celebrations.

Events are planned around the country, with public engagement and student involvement to the fore. For instance, the annual Trinity Week last week chose to make light the central theme of its celebrations.

Light has always been central to human civilisation, illuminating the dark and serving as a spiritual touchstone. The Newgrange passage grave was built 5,000 years ago, with light its central element. It was built 300 years before Stonehenge and 900 years before the great pyramids, and it still works as a timepiece that uses light to mark the winter solstice.

Today light is being called upon to deliver far more, including overcoming the limits inherent in conventional electronics.Water treatment, the internet, cinema, scientific discovery and medical diagnosis and therapy all use photonics, says Leahy.

“Photonics is a key enabling technology, and, like electronics, is found in pretty much everything,” says Prof Paul Townsend, the director of the Irish Photonic Integration Centre in Cork.

Tyndall National Institute hosts the centre and includes Cork Institute of Technology, Dublin City University, University College Cork and 18 companies in a partnership to develop the next generation of photonics devices.

“We are focusing on optical fibre technology, communications and important medical instruments such as integrated sensing or imaging systems integrated into surgical instruments,” he says.

The goal is to bring new light-based systems to market. Examples include the use of laser technology to measure carbon dioxide levels in the atmosphere, and adding sensors to existing medical devices used to insert stents to open up a blocked artery.

Photonics will not replace electronics, at least not in the short term. Rather it will add new functionality and new services to enhance what can be achieved. For example, the high-quality screen displays on smartphones rely on blue light-emitting diodes, which also help to light up your Christmas tree.

Night study

There are other uses for light technology. "There are an estimated one billion people still using oil maps to read at night," says Leahy. "Being able to read and study at night can be critical in education, and so a billion people are effectively dispossessed. Allowing hundreds of millions of kids to read at night is a key strategic goal for the IEEE [Institute of Electrical and Electronics Engineers]."

The UN sees the International Year of Light as a way to level the playing field, to make newly affordable light-based technologies available to people around the world. It seeks to raise awareness of how optical technologies can promote sustainable development and deliver solutions to worldwide challenges in energy, education, agriculture, communications and health.

Astronomers, for their part, will also be hoping the year brings a reduction in light pollution, which can spoil our view of the night skies. Scattered urban illumination is washing out spectacular night-time sights such as the Milky Way. Even in rural areas, localised lighting can diminish the night-time display.

[ light2015.ie ]

DARK CLOUD: SIX-FIGURE COST OF LIGHT POLLUTION

Ireland is spending hundreds of thousands of euro a year shining light up into empty space. Nothing gets illuminated and the electricity used is wasted, but we do it year in, year out just the same.

Trinity College Dublin physicist and astronomer Prof Brian Espey is not happy about this and has carried out research into this costly approach to providing urban lighting. His findings make interesting reading in this, the International Year of Light, when we are encouraged to understand how light in its many forms is involved in and enhances our daily lives.

Light pollution, however, is not among the list of positives. There are a range of impacts, including the cost of the energy, environmental damage and possible human health concerns, says Espey.

Inefficient lamps and light standards are the main causes of the light pollution produced by urban lighting systems, which provide lighting at ground level but also project it where it can’t be used: into the night sky.

This is not a trivial consideration. The 420,000 street lights in Ireland burn up 205 gigawatt hours of electricity each year, at a cost of about €29 million, says Espey. Producing this power causes the release of 110,000 tonnes of carbon dioxide.

A large fraction of this energy, 20-30 per cent, is wasted through poorly designed or inefficient lighting, he says.