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Ultrafast THz Photonics Lab
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Dr. Ranjan Singh

Assistant Professor

Division of Physics and Applied Physics

Nanyang Technological University, Singapore

Education

I earned B. Eng. degree in Telecommunications from Bangalore University in 2001, and M. Tech in Optoelectronics and Laser Technology from Cochin University of Science and Technology in 2004 and a PhD degree in Photonics from Oklahoma State University in the year 2009. After four years of post-doctoral research experience at Los Alamos National Laboratory, I joined the School of Physical and Mathematical Sciences, Division of Physics and Applied Physics in 2013 as an Assistant Professor where I direct my own research group focused on ultrafast terahertz photonics and material physics. I am also a part of Centre for Disruptive Photonic Technologies, The Photonics Institute, NTU.

Research

My research interests are in the area of sensors, slow light, superconductors, low dimensional materials, optoelectronics, metamaterials, active photonic devices, and classical analogues of quantum phenomena.

We are an experimental terahertz spectroscopy group focused on ultrafast response of materials upon illumination with extremely short pulsed light ranging from picosecond to femtosecond time scale. Broadly, our research interests are in the areas of novel material physics, micro-nanophotonics, high temperature superconductivity, plasmonics, metamaterials and terahertz spectroscopy. The problems that we are trying to address would lead to large scale applications in sensors, solar cells, non-destructive testing, imaging, and quantum communication technologies by unraveling the opto-electronic ultrafast dynamics of materials. We work extensively with on ultrafast photonics, material physics and engineering of innovative disruptive technologies that will impact our society in the near and distant future. We also design, fabricate, and characterize of novel photonic devices and explore their applications in information, sensing and energy.

We channel our efforts to change this world through our fascinating discoveries and understanding of the physics of new materials that could be applied to light based applications such as LEDs, Solar cells, Sensors, and Quantum technologies. We are excited about how our understanding of novel materials and its response to light could lead to innovative future technologies.

 

Current Projects

# 1 Active and Passive Materials

Metamaterials are artificially engineered materials that provides unprecedented manipulation of light at micro-nanoscales that has the potential to impact the future photonics technologies in the areas of sensors, low energy switching, quantum gates, communication devices, efficient filters, enhancement of evanescent fields, and imaging with resolution higher than the diffraction limit of light.

In this group, we explore metadevices for sensing, polarization conversion, active modulation, high quality factor metacavities, slow light effects, and near field manipulation.

# 2 Mid-IR to UV pump and Terahertz probe transient spectroscopy of Novel Materials

Terahertz time-domain spectroscopy is the only contact free, all optical, non-invasive technique to probe the conductivity and transport properties in bulk and low-dimensional materials. The low energy feature (1 THz = 4.13 meV) of the terahertz pulse is ideally suited for probing the phonon resonances and the intraband transitions in ultrathin film/ low-dimensional materials. The variable wavelength pump (2600 - 260 nm) and terahertz probe spectroscopy allows us to excite the carriers from valence band to the conduction band and monitor the non-equilibrium time evolution of carriers with sub-ps time resolution.

Our interest is to characterize new materials that could have applications in solar cells, superconductivity, lasers, LEDs and optoelectronic components and devices.

# 3 High-Tc superconductivity

High-Tc superconductivity is one of the ground breaking discoveries of physics. Superconductors are the only macroscopic quantum mechanical system that holds the key for the design and development of quantum computers. Therefore, we have tremendous interest in superconducting technologies. Since the energy of the terahertz waves lie below the superconducting gap, it is an ideal tool to probe the Cooper pairs and measure their ac complex conductivity.

We explore novel material systems that could have superconducting properties and also look at the interaction between superconducting carriers and the meta-atom arrays through designing active superconducting metamaterial and plasmonic systems.

 

Group Members

We are a vibrant and dynamic group where people with different skills work towards a common objective.

Post Doctoral fellow

Dr. Govind Dayal

"Govind Dayal received his Ph.D. from Indian Institute of Technology Kanpur, India, in 2014. His doctoral research was focused on the theoretical and experimental study of tuneable metamaterials for infrared multi-spectral absorbers. He joined the School of Physical and Mathematical Sciences, Division of Physics and Applied Physics in 2014 as a post doctoral fellow. His current research focuses on the hybridization of plasmon modes to generate new plasmon modes with controllable line-width and line shape, and to study the light matter interaction for surface enhanced optical phenomena such as SEIRA, photo-luminescence of the newly emerging materials."

Email: DAYAL@NTU.EDU.SG

Google Scholar Page: https://scholar.google.com/citations?user=pJyEtJwAAAAJ&hl=en

Personal website: https://sites.google.com/site/gdayal2015/

PhD Student

Cong Longqing

"Longqing obtained B. Eng. Degree in optoelectronics from Tianjin University in 2011 and M. Eng. Degree in optical engineering from Tianjin University in 2014 and joined the group in Jan. 2014 pursing the PhD degree. Longqing’s research interests include polarization optics, active photonic devices, ultrasensitive sensors, novel optical components, superconductors, low-dimensional materials and interesting physical phenomena like Fano resonance and Toroidal moment in metamaterials. His works related to these topics have contributed 26 journal publications till now with more than 370 citations and an h-index of 10."

Email: CONG0006@NTU.EDU.SG

Personal website: https://sites.google.com/site/longqingcong/

PhD Student

Manukumara Manjappa

"Manu is an Integrated MSc in Physics Graduate from University of Mysore, India. Received Masters by Research degree in experimental quantum optics from National University of Singapore, Singapore. Currently pursuing PhD in Division of Physics and Applied Physics, Nanyang Technological University, Singapore. His current research topic is “Probing the near field light matter interactions in metamaterials in the terahertz spectrum of electromagnetic radiation”. Earlier his research was focused on the quantum optics experiments using the vapor as well as ultracold alkali atoms. He has worked on laser cooling and trapping of rubidium atoms and probed the electromagnetically induced transparency phenomenon in various atomic systems."

Email: S140001@NTU.EDU.SG

Google Scholar Page: https://scholar.google.com.sg/citations?user=U9RGq8YAAAAJ&hl=en

PhD Student

Yogesh Kumar Srivastava

"Yogesh Srivastava completed his B.Sc and M.Sc degree in Physics from University of Lucknow in 2006 and 2008, respectively. He earned his M. Tech in Materials Science from Indian Institute of Technology Kanpur (IIT Kanpur) in 2011. He has three years of industrial experience as Materials Failure Analysis Specialist at Finisar Malaysia Sdn. Bhd. Malaysia. In 2014 he has joined the School of Physical and Mathematical Sciences, Division of Physics and Applied Physics from Nanyang Technological University as an Ph.D. scholar in Prof. R.Singh's research group. His research interests are in the field of metamaterials, terahertz spectroscopy, superconductors, flexible electronics and low dimensional materials."

Email: YOGESHKU001@NTU.EDU.SG

Google Scholar Page: https://scholar.google.com/citations?user=xe8IutUAAAAJ&hl=en

PhD Student

Manoj Gupta

"Manoj Gupta received his bachelor of technology degree in Electrical Engineering from Indian Institute of Technology Roorkee, India in year 2007. Currently he is pursuing PhD in Division of Physics and Applied Physics, Nanyang Technological University, Singapore. He has his working experience in oil sector, as well as in education sector. His current research interests are focused in the field of metamaterials, such as terahertz spectroscopy, active and tunable toroidal metasurfaces."

Email: MANOJ010@NTU.EDU.SG

Google Scholar Page: https://scholar.google.com.sg/citations?user=58xx018AAAAJ&hl=en

PhD Student

Song Han

"Song Han received his B.S. in Physics from Central China Normal University (CCNU), P. R. China. He has some experience with metamaterials. His current research involves polarized light and control, Fano resonance (electromagnetically induced transparency, EIT) in planar/3-D metamaterials and application, metamaterial-based toroidal moment and application. In 2015, he has joined the School of Physical and Mathematical Sciences, Division of Physics and Applied Physics as Ph.D. scholar in Nanyang Technological University, Singapore."

Email: HANS0028@NTU.EDU.SG

Google Scholar Page: https://scholar.google.com.sg/citations?user=loAJGhoAAAAJ&hl=en

Contact

Communicate with us to discuss and collaborate on topics of mutual research interest. Come by for an informal chat to discuss what the projects are about or discuss variations.

Office

SPMS-PAP-03-13
Division of Physics & Applied Physics
School of Physical & Mathematical Sciences
Nanyang Technological University, Singapore
Call: (+65) 63162965
Email: RANJANS@NTU.EDU.SG

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