PhD Candidate
Columbia University
Areas of Interest
- Integrated Circuits
- Micro/Nano Electro Mechanical Systems
- Nanophotonics and Solid State Physics
- Quantum Optics
Poster
Low-loss composite photonic platform based on 2d semiconductor monolayers
Abstract
Despite significant advances in integrated photonics over the past decade, an efficient integrated phase delay that forms the backbone of applications including LIDAR, quantum circuits, optical neural networks and optical communication links, remains to be demonstrated. The problem is fundamental – silicon phase modulators rely on either slow, yet highly power consuming thermo-optic effect to induce pure phase change or relatively faster plasma dispersion effect, which not only changes the phase of the propagating mode but also induces significant absorption. The need of the hour is a material or a photonic structure that can induce significant phase change with minimal absorption and has relatively low electrical power consumption (∼ 1 fJ/bit). 2D materials are promising for optical modulation, detection and light emission because their optical properties can be tailored on-demand by electrostatically doping the monolayers. The ease of integration, strong light-matter interaction and large-scale growth of 2D materials enable their widespread applicability in emerging large scale systems. Till date, researchers have pre-dominantly concentrated on the electro-absorptive properties of semi-metal graphene and TMDs near their excitonic resonances, where the optical insertion loss is prohibitively high for photonic applications. Here, we have shown that monolayer TMD exhibits strong electro-refractive modulation at near infrared (NIR) wavelengths, to the extent that the doping induced change in the real to the imaginary part of refractive index (|Δn/Δk|) ∼ 125 for semiconductor monolayers, which is an order of magnitude higher than the |Δn/Δk| reported for graphene (∼ 3.5) and traditional bulk materials such as silicon (∼ 10 - 20). To leverage the doping dependent strong electro-refractive response of TMDs for photonic applications, we have developed a fully integrated silicon nitride-TMD hybrid platform that gates the monolayer capacitively to achieve a modulation efficiency of 0.8 V cm with extremely low power consumption that can find applications in neuromorphic computing, optical neural networks, quantum circuits and LIDAR.
Bio
Ipshita Datta is a Ph.D. student in Professor Michal Lipson’s group at Columbia University in the Electrical Engineering (EE) Department. She has completed her Masters’ degree from Indian Institute of Technology Kharagpur (IIT), India. Her masters’ research focused on optical interconnect design for network-on-chip technology with BER and transmit power constraints. Her graduate research focuses on merging the fields of material science with state-of-the-art nanophotonics to develop the next generation photonic-2D material hybrid platform that enables enhanced light-matter interaction to probe the linear and non-linear optical response of novel materials. She is interested in leveraging the strong light-matter interaction in 2D materials with photonic structures to enable applications including quantum computation, networking and sensing.
