Discovery by CUNY-led Research Team Offers Potential for More Efficient Solar Cells, Super Bright LEDs and Ultra-High Sensitive Sensors

April 16, 2012 | The University

A team of physicists headed by Dr. Vinod M. Menon, who is a member of The City University of New York Photonics Initiative and teaches at Queens College, has discovered a new method to manipulate light that could eventually result in more efficient solar cells, super bright LEDs, ultra-high sensitive sensors and single photon sources necessary for quantum communication protocols and quantum computers.

The Photonics Initiative was established in 2000 to bring CUNY into the highest ranks of university photonics research through cluster hiring of new faculty, development of new facilities, and expansion of educational opportunities in photonics. Dr. Menon is also a member of the New York State Center for Advanced Technology in Photonics Applications at CUNY and is Associate Professor of Physics at Queens College and at the CUNY Graduate Center.

He is the co-author of an article about the discovery, entitled “Topological Transitions in Metamaterials,” published in Science on April 13, 2012. The research team includes physicists from Queens College, The City College/CUNY, the University of Alberta, Canada, and Purdue University. Their research has been underway for two years.

Borrowing an idea from the field of mathematical topology, the scientists have created an artificial material — called “metamaterial” — that can transform from regular dielectric (a substance like glass or plastic, which does not conduct electricity) to a medium that behaves like metal (reflects) in one direction and like dielectric (transmits) in the other. The optical properties of this metamaterial can be mapped onto a topological transformation of an ellipsoidal surface into a hyperboloid.

Topology is the mathematical field dealing with the properties of objects undergoing deformations, such as stretching and twisting. The ellipsoid and hyperboloid belong to different classes of surfaces, the former being closed (bound) and the latter being open (unbound). The topological transition from such a bound (elliptic) to an unbound (hyperbolic) surface manifests itself in the real world as a dramatic increase of light intensity inside the material.

The breakthrough optical topological transition was exploited by the research team to manipulate the propagation of light within the metamaterial. This aspect was then used by the physicists to demonstrate modification in the light emission of a nanoparticle placed in the vicinity of the metamaterial.

An animation illustrating the optical topological transition occurring in metamaterials.

“While this is a fundamental work, the effect reported here in metamaterials offers the promise of multiple applications in a number of important fields,” stated Dr. Menon. “For example, it can help in enhanced light harvesting, which could result in more efficient solar cells. It may also be used to develop single photon
sources necessary for quantum communication protocols and quantum computers. Through engineering of transmission properties of these systems, and by combining them with light emitters, one may also realize super bright LEDs that would be useful for display applications.”

The experimental part of the research was led by Queens College in collaboration with City College, and the theoretical work was carried out at Purdue and Alberta. The work was funded by the Army Research Office, the National Science Foundation/Division of Materials Research, The City University of New York, and the Natural Sciences and Engineering Research Council of Canada. Part of the experimental work was carried out at the Center for Functional Nanomaterials at Brookhaven National Laboratory.

Dr. Menon heads the Laboratory for Nano and Micro Photonics at Queens College, where his group has been exploring light-matter interaction at the nano and micron scale. The main research areas are development of light confining structures such as microcavities and waveguides, and artificially engineered optical materials such as metamaterials and hybrid (organic/inorganic) nanocomposites. He is also a member of the Center for Photonic and Multiscale Nanomaterials (C-PHOM). Dr. Menon has been active mentoring high school science students, four of whom won first place awards at the 2011 New York City Science and Engineering Fair. Their projects were among eight selected to be visited by President Barack Obama when he attended the Fair.

Dr. Menon joined Queens College’s department of physics in 2004. Prior to that he was a research staff member (2003 – 04) and postdoctoral fellow (2001 – 2003) at Princeton University. He received his M.S. in physics from the University of Hyderabad, India in 1995, and his Ph.D. from the University of Massachusetts in 2001.

The other members of the research team and authors of the Science paper include: Harish Krishnamoorthy: Graduate Student – Department of Physics, Queens College and The Graduate Center/CUNY; Zubin Jacob: Assistant Professor – Department of Electrical Engineering, University of Alberta, Canada; Evgenii Narimanov: Associate Professor – Department of Electrical Engineering, Purdue University; and IIona Kretzschmar: Associate Professor – Department of Chemical Engineering, The City College/CUNY.

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