Light-manipulating materials produce an exciting field
Special “metamaterials” have provided researchers with new and exciting ways to control the behavior of light, said Palestinian materials scientist Hala J. El-Khozondar during a TWAS Medal Lecture. Reflecting on her own work in the field, the Palestinian researcher said the applications are broad and are already having a powerful impact in medical, security and solar technology.
El-Khozondar is a 2011 TWAS Fellow and she has won worldwide scientific respect for her research, which has had implications for wireless communication, optical communication, optical fibre sensors, renewable energy and other areas. She currently is a professor in the electrical engineering department at the Islamic University of Gaza.
Based on her accomplishments, she was awarded a TWAS Medal and invited to deliver the TWAS Medal Lecture on 29 November at the Academy's 28th General Meeting. The TWAS Medal Lectures were established in 1996; a General Meeting typically features two or three leading scholars who been awarded the honour and invited to present their work.
El-Khozondar’s focus has been on metamaterials, structures in which atoms are arranged in a pattern where each is less than one nanometer from the other. This distance is much less than the wavelength of visible light, and by adjusting the distance between the atoms within metamaterials, scientists can make light bend and bounce in ways that open up new options for innovation to researchers throughout countless fields.
Making her work even more remarkable is that El-Khozondar’s research was developed in the Palestinian Territories, at the Islamic University of Gaza, where she and her colleagues had scarce resources and no access to advanced equipment such as high-powered microscopes.
“We work much harder than normal,” she said. “We spend a lot of time doing paperwork and computer simulations.”
El-Khozondar will speak on the scientific experience of a woman physicist in Gaza, Palestine, at The International Centre for Theoretical Physics (ICTP) in Trieste, Italy, on Thursday, 24 January at 4 p.m. Learn more about the special seminar here.
The idea for metamaterials has been around since 1968, conceived of by the Russian physicist Victor Veselago. But wasn’t produced in a lab until 2000, in an experiment proposed by British physicist John Pendry and carried out by American physicist David R. Smith. Since then, they have been used in numerous fields.
“These metamaterials have attracted attention the last decade,” El-Khozondar said. “And they attracted a lot of attention because they have applications.”
The way metamaterials refract light is not found in nature. One way to conceive of it is to imagine a glass of water with a straw in it. Light can move directly through air without changing direction, but it will bend at an angle when it hits water in a glass, making a straw in the water look slightly off, as if it at a different angle below the water line. But the light will still generally still travel in a similar direction, so the straw does not look drastically disjointed. A straw in “negative” water functions as metamaterials do: once that light hits the water, it will bounce back the way it came as if it ricocheted off an invisible wall placed down the middle of the water. Since the behavior of light determines what the human eye will see, the portion of the straw inside the water would appear wildly out of place, entering the water at a completely different location.
This effect provides researchers with precise control over the behavior of light.
The material is useful in communication, because it provides for more radio antennae designs by presenting more options for manipulating light. It’s also useful for security technology as well as camouflage and stealth technology, making people and objects – and even their shadows – invisible to the naked eye. An object surrounded by a “cloaking device” made of the metamaterial will be practically invisible to the naked eye.
El-Khozondar’s own work has also largely focused on improving crystals used to absorb light in solar panels and converting it to usable electricity. It can also help filter or amplify signals in transmission lines, improve sensors that detect bacterial changes in food, and improve the quality of lenses.
“They have a lot of application because we can control them,” she said. “We can control the gap size of the atoms, and these all affect the applications.”