Speaker: Dr. Ramachandra Rao Yalla, Asst. Professor, School of Physics, University of Hyderabad
Date/Time: Wednesday, 12th February 2025, 3:00 PM – 4:00 PM
Venue: SV Narsaiah Auditorium, IAP
Abstract: An optical fiber with a sub-wavelength diameter has opened promising new avenues in nanophotonics and quantum optics [1]. The key point is that the optical field can be tightly confined in the transverse direction, enabling the possibility of efficiently manipulating quantum emitters/photons. Recently, optical nanofibers (ONFs), optical nanofiber tips (ONFT), and optical nanocapillary fibers (NCFs) have proven to be promising candidates for efficiently manipulating photons/emitters. In this presentation, I shall show the fabrication of the ONFT/ONF using chemical etching/gas-flame technique. Regarding ONFT, the observed optical transmissions are more than 30%, and tip diameters are less than 500 nm [2]. The channeling of fluorescence photons from quantum dots into guided ONFT modes is demonstrated, with good agreement with simulation results [3]. Regarding ONF, we design the pulling parameters in a four-step process to achieve the desired diameter. The measured diameters range from 480 to 530 nm, showing good correspondence with the designed diameters [4]. Additionally, we demonstrate the in-situ fiber characterization using scattering loss analysis [5]. Further, I shall discuss the efficient channeling of single photons from a single quantum emitter into guided modes of NCFs. The NCF is formed of a liquid core optical nanofiber with inner and outer diameters. We optimize the inner and outer diameters of the NCF filled with water medium by placing a single dipole source (SDS) inside. The maximum channeling efficiency of 52% is found when the radially polarized SDS is placed at the center of the NCF filled with the water medium [6]. Further, we numerically report highly efficient coupling of single photons using a pair of nanostructures [7]. The present platforms may open new possibilities in quantum networks
References:
[1] K. P. Nayak, M. Sadgrove, R. R. Yalla, F. L. Kien, and K. Hakuta, J. Opt. 20, 073001 (2018).
[2] Resmi M, E. Bashaiah, and R. R. Yalla, Journal of Nanophotonics 18, 026007 (2024).
[3] Resmi M, E. Bashaiah, and R. R. Yalla, J. Opt. 26, 065401 (2024).
[4] E. Bashaiah, S. Suman, Resmi M, B. Das, and R. R. Yalla, Journal of Nanophotonics 18, 036007 (2024).
[5] S. Suman, E. Bashaiah, Resmi M, and R. R. Yalla, J. Appl. Phys. 135, 123101 (2024).
[6] E. Bashaiah, Resmi M, and R. R. Yalla, Opt Quant Electron 56, 893 (2024).
[7] Resmi M, E. Bashaiah, S. Suman, and R. R. Yalla, Opt Quant Electron 56, 1341 (2024).
Speaker Bio: Dr. Ramachandra Rao Yalla received his MSc from the University of Hyderabad and his PhD from the University of Electro-communication, Japan. He is an active researcher and an excellent, committed teacher, currently working as an Assistant Professor in the School of Physics at the University of Hyderabad. His research interest is the research area of quantum photonics with sub-wavelength diameter silica Fibers termed optical nanofibers. He has received support from national funding agencies for establishing an advanced quantum photonics laboratory at the University of Hyderabad. His group at the University of Hyderabad focuses on quantum photonics and plasmonics and readily suits commercial applications in quantum technologies.