Light is the science of the future — how Africans are using it to solve local challenges

Daily Maverick

2 days ago

Photonics is regarded as the science of the future and students and academics on the continent are making great strides in finding applications to address Africa's needs.
Light is all around us, essential for one of our primary senses (sight) as well as life on Earth itself. It underpins many technologies that affect our daily lives, including energy harvesting with solar cells, light-emitting diode (LED) displays and telecommunications through fibre optic networks.
The smartphone is a great example of the power of light. Inside the box, its electronic functionality works because of quantum mechanics. The front screen is an entirely photonic device: liquid crystals controlling light. The back of the phone too: white light-emitting diodes for a flash, and lenses to capture images.
We use the word photonics, and sometimes optics, to capture the harnessing of light for new applications and technologies. Their importance in modern life is celebrated every year on 16 May with the International Day of Light.
Despite the resource constraints under which they work, scientists on the African continent have made notable contributions to photonics research.
Some of their research has been captured in a recent special issue of the journal Applied Optics. Along with colleagues in this field from Morocco and Senegal, we introduced this collection of papers, which aims to celebrate excellence and show the impact of studies that address continental issues.
A spotlight on photonics in Africa
Africa's history in formal optics goes back thousands of years, and references to lens design were already recorded in ancient Egyptian writings.
In more recent times Africa has contributed to two Nobel prizes based on optics. Egyptian-born Ahmed Zewail watched the ultrafast processes in chemistry with lasers (1999, Nobel Prize for Chemistry) and Moroccan-born Serge Harouche studied the behaviour of individual particles of light, or photons (2012, Nobel Prize for Physics).
Unfortunately, the African optics story is one of pockets of excellence. The highlights are as good as anywhere else, but there are too few of them to put the continent on the global optics map. According to a 2020 calculation done for us by the Optical Society of America, based on its journals, Africa contributes less than 1% to worldwide journal publications with optics or photonics as a theme. Yet there are great opportunities for meeting continental challenges using optics. Examples of areas where Africans can innovate are:
Bridging the digital divide with modern communications infrastructure;
Optical imaging and spectroscopy for improvements in agriculture and monitoring climate changes;
Harnessing the sun with optical materials to produce clean energy;
Bio-photonics to solve health issues; and
Quantum technologies for novel forms of communicating, sensing, imaging and computing.
The papers in the special journal issue touch on a diversity of continent-relevant topics.
One is on using optics to communicate across free-space (air) even in bad weather conditions. This light-based solution was tested using weather data from two African cities, Alexandria in Egypt and Setif in Algeria.
Another paper is about tiny quantum sources of quantum entanglement for sensing. The authors used diamonds, gems found in South Africa and more commonly associated with jewellery. Diamonds have many flaws, one of which can produce single photons as an output when excited.
The single photon output was split into two paths, as if the particle went both left and right at the same time. This is the quirky notion of entanglement, in this case, created with diamonds. If an object is placed in any one path, the entanglement can detect it. Strangely, sometimes the photons take the left path but the object is in fact in the right path, yet still it can be detected.
One contributor proposes a cost-effective method to detect and classify harmful bacteria in water. New approaches in spectroscopy (studying colour) for detecting cell health; biosensors to monitor salt and glucose levels in blood; and optical tools for food security all play their part in optical applications on the African continent.
Another area of African optics research that has important applications is the use of optical fibres for sensing the quality of soil and its structural integrity. Optical fibres are usually associated with communication, but a modern trend is to use the optical fibre already laid to sense for small changes in the environment, for instance, as early warning systems for earthquakes. The research shows that conventional fibre can also be used to tell if soil is degrading, either from lack of moisture or some physical shift in structure (weakness or movement). It is an immediately useful tool for agriculture, building on many decades of research.
The diverse range of topics in the collection shows how creative researchers on the continent are in using limited resources for maximum impact. The high orientation towards applications is probably also a sign that African governments want their scientists to work on solutions to real problems rather than purely academic questions. A case in point is South Africa, which has a funded national strategy (SA QuTI) to turn quantum science into quantum technology and train the workforce for a new economy.
Towards a brighter future
For young science students wishing to enter the field, the opportunities are endless. Although photonics has no discipline boundaries, most students enter through the fields of physics, engineering, chemistry or the life sciences. Its power lies in the combination of skills, blending theoretical, computational and experimental, that are brought to bear on problems. At a typical photonics conference there are likely to be many more industry participants than academics. That's a testament to its universal impact in new technologies and the employment opportunities for students.
The previous century was based on electronics and controlling electrons. This century will be dominated by photonics, controlling photons. DM
First published by The Conversation.
Andrew Forbes is a professor at the University of the Witwatersrand. DM
Patience Mthunzi-Kufa is a distinguished professor at the University of South Africa.
Professor Zouheir Sekkat of Mohammed V University in Rabat, who is the director of the Pole of Optics and Photonics in the Moroccan Institute for Advanced Science, Innovation and Research at Mohamed VI Polytechnic University in Benguerir, Morocco, contributed to this article.
This story first appeared in our weekly Daily Maverick 168 newspaper, which is available countrywide for R35.