Electronically Controlled Quantum Confinement for Tunable Plasmonic Metasurfaces Vishal Kaushik 1 *, Swati Rajput 2 , Prem Babu 1 , Suresh Kumar Pandey 1 , Rahul Dev Mishra 1 , Mukesh Kumar 1,3 1 Department of Electrical Engineering, Optoelectronic Nanodevice Research Laboratory, Indian Institute of Technology (IIT) Indore, Indore, India 2 Electrical & Computer Engineering, University of Toronto, Canada 3 Centre for Advanced Electronics (CAE), Indian Institute of Technology (IIT) Indore, Indore, India, E-mail: mukesh.kr@iiti.ac.in Unprecedented optical functionalities and the ability to downscale the optical circuits beyond diffraction limit promise a key role for Plasmonic Metamaterials (PMs) in future photonic integrated circuits. However, dealing with fundamental challenges related to the absence of a high-speed switching mechanism, and high optical losses of metals is vital to leverage their exquisite properties. Here we demonstrate, for the first time (to the best of our knowledge), a novel approach for high-speed (7.5 GHz) voltage-controlled Localized Surface Plasmon Resonance (LSPR) in semiconductor-nanostructures at the telecommunication window. The proposed approach is based on tuning the confinement of charge carriers from 1-D to 0-D in semiconductor nanowire on a cost-effective fabrication process based on Anodized Aluminum Oxide (AAO) template. Moreover, the concept in- principle will be compatible with most semiconductors allowing exciting applications in tunable metasurfaces, spasers, modulators, and many more. The ongoing race for the development of ever faster and smaller optical circuits has hit a fundamental roadblock due to diffraction size of the photons, thus down-scaling opto-electronic circuits to sub-wavelength regime has become a major challenge. The excitation of the Localized Surface Plasmons Resonance (LSPR) in metal nanostructures, has been widely touted as a promising approach for enabling sub-wavelength light confinement 1,2 . By merging nanoscale integration offered by nanoelectronics with broad bandwidth of photonics; plasmonics is primed to replace photonics. Recently a new class of materials called Plasmonic Metasurfaces (PMs), which are a 2D ensemble of such plasmonic resonators, have recently become a subject of intense research interest, owing to their ability to control and shape light at nanoscale 3-5 . These structures exhibit unprecedented optical functionalities which are beyond the standard response of the materials they are made from. The shape and size of such structures can be engineered for application specific properties. Traditionally, metals have been the material-of-choice for realizing the basic building blocks of plasmonic metasurfaces however, high optical losses due to extremely high negative-permittivity 6,7 and surface scattering along with lack of advance switching mechanism (post-fabrication) has significantly hampered their feasibility for various applications towards tunable photonics and adaptive optics.