Browsing by Author "Soman, Anishkumar"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Controlling Microring Resonator Extinction Ratio via Metal-Halide Perovskite Nonlinearity(Advanced Optical Materials, 2021-09-09) Wang, Feifan; Zhao, Lianfeng; Xiao, Yahui; Li, Tiantian; Wang, Yixiu; Soman, Anishkumar; Lee, Hwaseob; Kananen, Thomas; Hu, Xiaoyong; Rand, Barry P.; Gu, TingyiThe exceptionally high optical nonlinearities, wide bandgap, and homogeneity in solution-processed metal-halide perovskite media are utilized as optical nonlinear elements on a silicon photonic platform for low-power-active components, such as all-optical switches, modulators, and lasers. With room temperature back-end-of-line compatible processing, a hybrid metal-halide perovskite (CH3NH3PbI3) microring resonator (MRR) structure is fabricated on a foundry-processed low-loss silicon photonic platform. With in-plane exci-tation near the light intensity of 110 W m−2, strong two-photon absorption and free-carrier absorption saturation are observed. With 103 field enhancements by MRRs, the photorefractive effect in the metal-halide perovskite reduces linear absorption, represented by 102 improvement of the MRR’s intrinsic quality factor and 20 dB enhancement of the extinction ratio.Item Graphene Absorption Enhanced by Quasi-Bound-State-in-Continuum in Long-Wavelength Plasmonic–Photonic System(Advanced Optical Materials, 2022-09-07) Kananen, Thomas; Wiggins, Marcie; Wang, Zi; Wang, Feifan; Soman, Anishkumar; Booksh, Karl; Alù, Andrea; Gu, TingyiGraphene plasmonic structures can support enhanced and localized light–mater interactions within extremely small mode volumes. However, the external quantum efficiency of the resulting devices is fundamentally limited by material scattering and radiation loss. Here, such radiation loss channels are suppressed by tailoring the structure to support a symmetry-protected bound-state-in-the-continuum (BIC) system. With practical loss rates and doping level in graphene, over 90% absorption near critical coupling is expected from numerical simulation. Experimentally measured peak absorption of 68% is achieved in such a tailored graphene photonic–plasmonic system, with maximum 50% contrast to the control sample without graphene. Significant reduction of the plasmon absorption for a different spacer thickness verifies the sensitivity of the system to the quasi-BIC condition.Item Optimizing fabrication techniques of materials and devices for integrated nanophotonics(University of Delaware, 2019) Soman, AnishkumarPhotonics is a branch of science which deals with the manipulation of light (“photons”) and has been growing exponentially in the last few decades due to the increased demands for faster data transfer, larger bandwidth, lower loss, lesser power requirement etc. To make these photonic devices we need to fabricate different active and passive device components. In this thesis, we have described the fabrication methodology and optimization techniques for such different photonic components. The thesis also discussed about different materials which find application in photonic devices. ☐ We discuss the importance of Silicon photonics and discuss the fabrication of different components namely waveguides, diffraction grating couplers, micro-ring resonators and photonic crystal waveguides. We explain in detail the process flow of fabrication of these components and the various challenges involved in each case. We also explain the methodology to overcome these problems and discuss optimization methods to improve the device quality. We characterize the quality of these components using loss analysis and performance measurements. We have explored the possibility of using amorphous silicon instead of crystalline silicon in photonics and tried understanding the limitations and possible ways to overcome them. We have also extended our study to bulk chalcogenides namely germanium antimony telluride (GST) by physical vapor deposition and indium selenide by exfoliation methods as materials having different applications in photonic industry. Beyond silicon we have extended our work to explore possibilities of two dimensional (2D) materials like graphene and organic materials in photonics. Some advanced applications are highlighted, the details of which will be reported in our future work.