Browsing by Author "Yadunath, T.R."
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Item Dependence of the 0.5 × (2e2/h) conductance plateau on the aspect ratio of InAs quantum point contacts with in-plane side gates(American Institute of Physics Inc. subs@aip.org, 2017) Das, P.P.; Jones, A.; Cahay, M.; Kalita, S.; Mal, S.S.; Sterin, N.S.; Yadunath, T.R.; Advaitha, M.; Herbert, S.T.The observation of a 0.5 × (2e2/h) conductance plateau in asymmetrically biased quantum point contacts (QPCs) with in-plane side gates (SGs) has been attributed to the onset of spin-polarized current through these structures. For InAs QPCs with the same width but a longer channel length, there is roughly a fourfold increase in the range of common sweep voltage applied to the SGs over which the 0.5 × (2e2/h) plateau is observed when the QPC aspect ratio (ratio of length over the width of the narrow portion of the structure) is increased by a factor 3. Non-equilibrium Green's function simulations indicate that the increase in the size of the 0.5 × (2e2/h) plateau is due to an increased importance, over a larger range of common sweep voltage, of the effects of electron-electron interactions in QPC devices with a larger aspect ratio. The use of asymmetrically biased QPCs with in-plane SGs and large aspect ratio could therefore pave the way to build robust spin injectors and detectors for the successful implementation of spin field effect transistors. © 2017 Author(s).Item Design, fabrication and characterization of 5 ?m ring resonator(2014) Kollia, V.R.; Yadunath, T.R.; Resmi, R.K.; Hegde, G.; Badrinarayana, T.; Das, P.P.; Srinivas, T.We present the design, simulation, fabrication and characterization of microring resonator on SOI platform. Proposed feature size device resonates at a wavelength of 1565.92 nm. The fabricated device has potential applications in communication and sensing. � OSA 2016.Item Design, fabrication and characterization of 5 μm ring resonator(Optica Publishing Group (formerly OSA), 2016) Kollia, V.R.; Yadunath, T.R.; Resmi, R.K.; Hegde, G.; Badrinarayana, T.; Das, P.P.; Srinivas, T.We present the design, simulation, fabrication and characterization of microring resonator on SOI platform. Proposed feature size device resonates at a wavelength of 1565.92 nm. The fabricated device has potential applications in communication and sensing. © OSA 2016.Item Integrated optics-based quantum communication devices(2017) Ramakrishnan, R.K.; Samad, S.A.; Archana, K.; Yadunath, T.R.; Das, P.P.; Talabattula, S.Quantum communication or more specifically quantum information processing is considered as the future of information science and technology. In this paper we propose a scheme to implement quantum communication at the device level using integrated optics. We implement the quantum communication protocol BB84, in a waveguide based circuit using integrated optics. We also propose a high dimensional quantum key distribution method implementation using integrated optics. In the earlier one polarized photons are used as the carriers of quantum information, while in second one electromagnetic modes in the waveguide are used to carry quantum information. The high dimensional quantum communication method is used to increase the information content of protocol thus increasing on the data rates. This is done by encoding into a larger state space. We have used electromagnetic modes for encoding since the polarization method is not efficient to carry information in a larger state space. � 2017 SPIE.Item Integrated optics-based quantum communication devices(SPIE spie@spie.org, 2017) Ramakrishnan, R.K.; Samad, S.A.; Archana, K.; Yadunath, T.R.; Das, P.P.; Srinivas, T.Quantum communication or more specifically quantum information processing is considered as the future of information science and technology. In this paper we propose a scheme to implement quantum communication at the device level using integrated optics. We implement the quantum communication protocol BB84, in a waveguide based circuit using integrated optics. We also propose a high dimensional quantum key distribution method implementation using integrated optics. In the earlier one polarized photons are used as the carriers of quantum information, while in second one electromagnetic modes in the waveguide are used to carry quantum information. The high dimensional quantum communication method is used to increase the information content of protocol thus increasing on the data rates. This is done by encoding into a larger state space. We have used electromagnetic modes for encoding since the polarization method is not efficient to carry information in a larger state space. © 2017 SPIE.Item Multiple Order and Broadband Optical Orbital Angular Momentum Source using a Single Photonic Crystal Device(Institute of Electrical and Electronics Engineers Inc., 2020) Yadunath, T.R.; Ravindran, R.; Hegde, G.; Das, P.P.; Srinivas, S.A promising optical integrated circuit device design for the generation of broadband, low order OAM modes with topological charges of +1 and +2 is successfully conceptualized using a combination of ring and point defect in thin photonic crystal slab structure with circular array of holes. © 2020 IEEE.Item Photonic crystal ring resonator: A promising device for a multitude applications(2017) Yadunath, T.R.; Kumar, R.R.; Sreenivasulu, T.; Kandoth, A.; John, K.; Ramakrishnan, R.K.; Das, P.P.; Badrinarayana, T.; Mohan, S.; Hegde, G.; Srinivas, T.In this paper a 2D Photonic Crystal array in SOI platform having hexagonal periodicity with a ring defect incorporated along with two bus waveguides is conceptualized and realized for various applications of optical communication, sensing etc. The ring structure filters out a resonant wavelength from the spectrum carried to it through the line defect where the resonated peak is determined by the effective ring radius. The hexagonal architecture enables more coupling length than an ideal ring structure which helps in better intensity accumulation. The resonant peak exhibited at 1554nm in simulation, which is observed in the optical characterization at 1543nm. This is attributed to the fabrication tolerance. � 2017 SPIE.Item Photonic crystal ring resonator: A promising device for a multitude applications(SPIE spie@spie.org, 2017) Yadunath, T.R.; Kumar, R.R.; Tupakula, T.; Kandoth, A.; John, K.; Ramakrishnan, R.K.; Das, P.P.; Badrinarayana, T.; Mohan, S.; Hegde, G.M.; Srinivas, T.In this paper a 2D Photonic Crystal array in SOI platform having hexagonal periodicity with a ring defect incorporated along with two bus waveguides is conceptualized and realized for various applications of optical communication, sensing etc. The ring structure filters out a resonant wavelength from the spectrum carried to it through the line defect where the resonated peak is determined by the effective ring radius. The hexagonal architecture enables more coupling length than an ideal ring structure which helps in better intensity accumulation. The resonant peak exhibited at 1554nm in simulation, which is observed in the optical characterization at 1543nm. This is attributed to the fabrication tolerance. © 2017 SPIE.