[Seminar] Active THz metamaterial photonics: From all-dielectrics to superconductors by Professor Ranjan Singh

Abstract:

Remarkable emergence of all-dielectric meta-optics governed by the physics of high-index dielectric resonators offer a low-loss platform for an efficient manipulation and subwavelength control of electromagnetic waves from microwaves to visible frequencies. Dielectric metasurfaces can focus electromagnetic waves, generate structured beams and vortices, enhance local fields for advanced sensing and provide novel functionalities for quantum technologies. Recent advances in meta-optics are associated with the exploration of exotic optical modes called the bound states in the continuum (BICs), which offer a simple interference mechanism to achieve large quality factors (Q) through excitation of supercavity modes in dielectric nanostructures and resonant metasurfaces. Here, I will discuss a BIC approach for active all-dielectric based meta-optics and photonics at terahertz frequencies and experimentally demonstrate active control of subwavelength supercavities with high-Q resonances that could be reconfigured at ultrafast timescales [1]. Such supercavities enable low power, all-optical switching and modulation of sharp resonances which could have promising dynamic applications. In this talk, I will also discuss electrically controlled microelectromechanical system (MEMS) based terahertz Fano resonances that show hysteresis type of response for logical gate applications and tera-nanophotonics [2]. Towards the end I will show some of our recent results on ultrafast, ultrathin superconducting metamaterials for extremely low-energy switching applications [3].

References:

1. S. Han, L. Cong, Y. K. Srivastava, B Qiang, M. Rybin, W. X. Lim, Q. Wang, Y. S. Kivshar, R. Singh, " All-dielectric active photonics driven by bound states in the continuum cavity", arXiv:1803.01992 (2018).

2. M. Manjappa, P. Pitchappa, N. Singh, N. Wang, N. Zheludev, C. Lee,, R. Singh," Reconfigurable MEMS Fano metasurfaces with multiple-input-output states for logic operations at terahertz frequencies" Nature Communications 9, 4056 (2018)

3. Yogesh Kumar Srivastava, Manukumara Manjappa, Longqing Cong, Harish N. S Krishnamoorthy, Vassili Savinov, Prakash Pitchappa, Ranjan Singh, “Superconducting dual-channel photonic switch” Advanced Materials 30, 1801257 (2018)

Biography:

Dr. Ranjan Singh is an Assistant Professor at the School of Physical and Mathematical Sciences, Division of Physics and Applied Physics, Nanyang Technological University (NTU) Singapore. He received his Ph. D. in Photonics from Oklahoma State University in 2009. Before joining NTU, he was a postdoctoral research associate at the Los Alamos National Laboratory from 2009 to 2013. His current research interest includes singular nanophotonics, biosensing, metamaterials, superconductor photonics, ultrafast optics, terahertz time resolved spectroscopy, and high Q metamaterial cavities for sensing and lasing applications. He has published more than 130 peer reviewed journal papers including Nature Communications, Advanced Materials, and Applied Physics Letters. Dr. Singh's metamaterial works has been highlighted by several scientific magazines and general public media such as Optics and Photonics news, MRS news, Materials 360 online news, Science news, Nanotechnology now, Photonics Online, Physics.org, and R&D magazine.