Invisibility cloak and beyond

29 August 2015

2005 Croucher fellowship recipient, Dr Jensen Li Tsan Hang, a physicist and senior lecturer from the Metamaterials Group in the School of Physics and Astronomy at the University of Birmingham, has been working on invisibility cloaks made from metamaterials.

Since the first invisibility cloak reported in 2006, scientists have been engineering refractive indices in metamaterials to control light to make the cloak work for all angles and multiple viewers. As this initial invisibility cloak worked only in the microwave spectrum, Li proposed a new strategy in 2008, called the carpet invisibility cloak. “It hides an object on the ground. This cloak is like a carpet placed on top of the object. It cancels out all the original scattering from the object, making us to perceive a flat ground again,” explained Li. Li then teamed up with experimentalists at UC Berkeley to work out the detailed design and construction of this cloak, working at infrared frequencies, which was published in 2009. More work was done to improve the carpet cloak so that it works at optical frequencies, theirs being the first optical carpet cloak published in 2010.

Li’s current research focuses on how metamaterials can be used to control waves in unexpected ways by exploring different strange wave phenomena and their possible applications. “The implication of the usage of metamaterials to realise an invisibility cloak is far-reaching. These metamaterials now gradually become a generic platform for us to investigate different wave phenomena that cannot be easily realised previously,” said Li. Li and his experimental collaborators have recently demonstrated metamaterials undergoing Parity-time phase transition, metasurfaces manipulating structured light, and have proposed how to use metamaterials to realise synthetic gauge field for photon.

Li received his B.Eng in electrical and electronic engineering from The University of Hong Kong and completed his doctoral studies at the Hong Kong University of Science and Technology in 2004. From 2005 to 2007, he received the Croucher Foundation; Postdoctoral Fellowship to work with Sir John Pendry in Imperial College London. He moved to the University of California at Berkeley as a postdoctoral researcher at the end of 2007. From 2009 to 2013, he was an assistant professor at the City University of Hong Kong before his current position. Li has been appointed senior lecturer in the University of Birmingham since March 2013.

To view Dr Jensen Li’s personal Croucher profile, please click here.

For details of the Croucher Fellowships for Postdoctoral Research, please click here.