http://hdl.handle.net/2289/7589 2026-04-08T15:43:53Z 2026-04-08T15:43:53Z Wu, Pengfei Philip, Reji Rao, Devulapalli V G L N http://hdl.handle.net/2289/8473 2025-08-28T04:24:27Z 2007-03-27T00:00:00Z

Title: Systems and Methods for Limiting Power using Photo-induced Anisotropy Authors: Wu, Pengfei; Philip, Reji; Rao, Devulapalli V G L N Abstract: Preferred embodiments of the present invention are directed at limiting power and controlling an output intensity of an optical system using photo-induced anisotropic materials. In a preferred embodiment, an azobenzene polymer film is used. The embodiments in accordance with the present invention include a cross-polarization system to provide clamping of the output intensity. A system for limiting power in accordance with a preferred embodiment of the present invention, includes a light source that provides an input light beam along a first optical path, a first polarizing element having a first polarization state positioned in the first optical path, a second polarizing element positioned in the first optical path having a second polarization state Substantially orthogonal to the first polar ization State, a sample having a photo-induced anisotropic material positioned in the first optical path, and a polarizer positioned in a second optical path at an angle of approximately 45 degrees to that of the input beam wherein an excitation beam provided in the second optical path spatially overlaps the input beam on the sample, and an output beam that is generated has a limited transmission value at high intensity.

2007-03-27T00:00:00Z Sinha, Urbasi Chatterjee, Sourav http://hdl.handle.net/2289/8362 2024-12-05T08:28:09Z 2024-11-21T00:00:00Z

Title: METHOD AND APPARATUS FOR OPTIMIZING PERFORMANCE OF A QUANTUM KEY DISTRIBUTION (QKD) PROTOCOL Authors: Sinha, Urbasi; Chatterjee, Sourav Abstract: The present disclosure relates to field of quantum cryptography that discloses method of optimizing performance of Quantum Key Distribution (QKD) protocol. Computing system (101) extracts one or more coincidence distribution sets generated from one or more timestamps detected during communication by one or more detector pairs associated with sender and receiver of communication. Further, computing system identifies one or more reference lines indicating signal value and noise value in each of one or more coincidence distribution sets. Thereafter, computing system determines time window in one or more coincidence distribution sets by iteratively adjusting one or more reference lines in incremental steps until at least one of, performance parameters, signal value and noise value within time window complies with predefined requirements. Finally, computing system optimizes performance of QKD protocol based on determined time window. present disclosure provides an advantage of optimizing individual Signal-to-Noise Ratio (SNR) while restricting QBER to predefined limit. Description: Open Access

2024-11-21T00:00:00Z Ramachandran, Hema Alouini, Mehdi Fade, Julien Bretenaker, Fabien http://hdl.handle.net/2289/7608 2021-07-28T06:25:46Z 2015-09-01T00:00:00Z

Title: System and method for navigation assistance in a scattering environment Authors: Ramachandran, Hema; Alouini, Mehdi; Fade, Julien; Bretenaker, Fabien Abstract: For performing navigation assistance in a scattering environment, a system is intended to detect at least one navigational light marker in scenes captured by an image capturing device, each navigational light marker generating a light beam having a predefined polarization state. The system includes an image capturing device that is adapted for: capturing a first image of a scene, said first image being polarized in accordance with the predefined polarization state of the light beam generated by said navigational light marker(s); capturing a second image of the scene, said second image being polarized according to a polarization state orthogonal to the polarization state of the first image; generating a polarimetric contrast image by combining the first and second captured images; and providing a feedback for performing navigation assistance in the scattering environment, on the basis of the generated polarimetric contrast image. Description: Open Access

2015-09-01T00:00:00Z Panigrahi, Swapnesh Ramachandran, Hema Fade, Julien Alouini, Mehdi http://hdl.handle.net/2289/7607 2021-07-28T06:26:19Z 2017-11-01T00:00:00Z

Title: Optical receiver for full-field optical quadrature demodulation Authors: Panigrahi, Swapnesh; Ramachandran, Hema; Fade, Julien; Alouini, Mehdi Abstract: An optical receiver for performing full-field quadrature demodulation of modulated light signals includes a first polarizing mechanism (P1), a second polarizing mechanism (P2, P3), a beam-splitting mechanism (BS2), an electro-optic modulator (EOM), a quarter-wave retarder mechanism (W), at least one camera sensor (C). The beam-splitting mechanism (BS2) separates incident light beam transmitted by the electro-optic modulator (EOM) so as to allow part of the incident light beam to pass via the quarter-wave retarder mechanism (W) before incurring polarization by the second polarizing mechanism, while another part of the incident light beam incurs polarization by the second polarizing mechanism without passing via the quarter-wave retarder mechanism (W). Q-quadrature and I-quadrature images are accordingly formed on the at least one camera sensor (C). The optical receiver further comprises circuitry configured to perform the full-field quadrature demodulation on the basis of light beams simultaneously acquired to obtain I-quadrature and Q-quadrature images. Description: Open Access

2017-11-01T00:00:00Z