I worked as a Research Professional in the laboratories of Professor Leslie A Rusch at COPL Laval University, Quebec City Canada, where I use insights from OAM fiber-based communication. I was working on optical communications. Optical communications are the backbone of our global society, touching every aspect of our lives. Optical links enable mobile telephony networks, social media, and commercial and governmental services. Fiber bandwidth is being exhausted as we approach the Shannon limit. We must re-invent the optical fiber to carry multiple modes of light where old fibers carry one. Increasing capacity combines advances in optical components such as fiber with the latest advances in electronic processing, including artificial intelligence to improve system architectures, digital signal processing, and component design. The project covers two broad areas of research: one in spatial division multiplexing (SDM) to carry multiple modes in a single fiber core, and one in machine learning (ML) for enhancing optical communications systems.

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I worked as a Postdoc Research Associate, at ETS Montreal, Canada (Prof. Bora Ung) (June 2018 to Oct 2020). My focus there was,  we demonstrate an optical pressure-sensing scheme based on FBG technology that provides a highly sensitive strain measurement with cm-scale axial resolution and fast response (μs scale) inside a surrogate spinal cord that is relevant to real-time in vitro studies of traumatic SCI. We also performed, the first experimental demonstration of both CVB and OAM beam transmission inside an endlessly mono-radial AC-PCF was performed. The stability of vector-vortex mode guiding in the AC-PCF was confirmed through polarimetric and interferometric measurements, which indicated good mode purity (>18 dB) over the whole 40 nm (17 THz) bandwidth investigated with a near-infrared.

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I also worked as a Postdoc Research Associate at A & M University and Baylor University, USA (Prof. Marlan O. Scully and Prof. H.W. Lee) (Nov 2016 to May 2018).  The objective of this project was the fabrication and optical characterization of Aluminum doped zinc oxide (AZO) with different nanostructures/concentrations for realizing a high sensitivity fiber-optical probe for the direct detection of glucose and biomolecules. To realize the probe, hollow code optical fiber was filled with AZO nanoparticles. An application of Raman spectroscopy was presented in the rapid characterization and identification of Aspergillus nidulans (mold) by showing that the Aspergillus nidulans have unique Raman spectral signatures. The distinct emission peaks from the Raman spectra provided detailed insight into the overall chemical composition of the Aspergillus nidulans. Importantly, we can identify whether the sexual (Candis pore) and asexual (ascospore) through the detected Raman signal.

 

I also worked as a Senior Research Assistant at City University of Hongkong (Prof. K.S. Chiang) (Feb 2015 to Oct 2016) Our study resulted in a fiber-optic sensor for pH measurement, which is a long-period fiber grating (LPFG) coated with a smart hydrogel. Our experimental sensor showed a sensitivity of ~0.66 nm/pH over the pH range from 2 to 12 and a response time of less than 2 seconds. We reported an LPFG sensor for phenolic compounds measurement which is an LPFG coated with tyrosinase-enzyme entrapped gel. The proposed sensor showed a sensitivity of ~0.06 nm/M for phenol. Compared with conventional prism SPR based or optical fiber-based structures, the use of an optical waveguide for SPR excitation, in particular, offers many advantageous features, such as small size, high sensitivity, and prospect of fabrication of multiple or multichannel sensors on a single chip. Waveguide SPR sensors formed with glass or silicon (Si) using gold (Au) or silver (Ag) as the plasmonic material have been studied both theoretically and experimentally. These studies confirm that optical waveguide is a promising platform for SPR sensing. This project also considered waveguide SPR sensor platform based on the polymer waveguide technology.  

I did my Ph.D. at IIT Delhi India (Prof. Banshi D. Gupta)(July 2010- Oct 2015) In particular, I have worked on the detection of pH and CrO42- by incorporating a pH/CrO42- sensitive hydrogel layer over an unclad core of the optical fiber with two consecutive layers of silver and ITO. The change of the fluid around the probe causes the swelling/shrinkage of the hydrogel layers resulting in the change of the refractive index. These sensors have short response time, stability, and remarkable sensitivity. SPR based fiber optic enzymatic biosensors have been developed for the detection of urea. The probe has the capability of online monitoring and remote sensing in addition to immunity to electromagnetic fields. The sensor has high sensitivity, a wide operating range, reusability, and reproducibility of results. Since the sensor is based on wavelength interrogation schemes, it is immune to source intensity fluctuation. I have also studied the detection of different gases such as hydrogen sulfide, ammonia, and chlorine using doped ITO thin film. Further, a bilayer (ITO/Ag) and gas clad (using ITO) based sensors have been studied for the enhancement of FOM and detection accuracy. It is based on the N-layer model and wavelength interrogation technique. The thicknesses of ITO and silver have been optimized to achieve the best performance of the sensor.

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I did two masters (Master of Science (Physics) and Master of Technology (Nanotechnology). I did my master's project at BARC (Bhabha atomic research Centre). Where I have focused on Gas sensing properties of pure and Au incorporated WO3 thin films towards H2S and Cl2 have been investigated. The sensor films were able to detect H2S and Cl2 selectively at an operating temperature of 150 and 200oC, respectively. Hydrothermal growth of ZnO nanowires were performed using ZnO nanoparticles as a seed layer. The growth was found to depend strongly on the reaction duration. These nanowires detected H2S with faster response and recovery time of 13 and 78 s, respectively towards 20 ppm at 350 oC.