Browsing by Author "Xiao, Yahui"
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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 Metasurface on integrated photonic platform: from mode converters to machine learning(Nanophotonics, 2022-07-20) Wang, Zi; Xiao, Yahui; Liao, Kun; Li, Tiantian; Song, Hao; Chen, Haoshuo; Uddin, S. M. Zia; Mao, Dun; Wang, Feifan; Zhou, Zhiping; Yuan, Bo; Jiang, Wei; Fontaine, Nicolas K.; Agrawal, Amit; Willner, Alan E.; Hu, Xiaoyong; Gu, TingyiIntegrated photonic circuits are created as a stable and small form factor analogue of fiber-based optical systems, from wavelength-division multiplication transceivers to more recent mode-division multiplexing components. Silicon nanowire waveguides guide the light in a way that single and few mode fibers define the direction of signal flow. Beyond communication tasks, on-chip cascaded interferometers and photonic meshes are also sought for optical computing and advanced signal processing technology. Here we review an alternative way of defining the light flow in the integrated photonic platform, using arrays of subwavelength meta-atoms or metalines for guiding the diffraction and interference of light. The integrated metasurface system mimics free-space optics, where on-chip analogues of basic optical components are developed with foundry compatible geometry, such as low-loss lens, spatial-light modulator, and other wavefront shapers. We discuss the role of metasurface in integrated photonic signal processing systems, introduce the design principles of such metasurface systems for low loss compact mode conversion, mathematical operation, diffractive optical systems for hyperspectral imaging, and tuning schemes of metasurface systems. Then we perceive reconfigurability schemes for metasurface framework, toward optical neural networks and analog photonic accelerators.Item Photocatalytic Oxidation in Few-Layer Tellurene for Loss-Invariant Integrated Photonic Resonance Trimming(Advanced Optical Materials, 2023-05-05) Mao, Dun; Wang, Yixiu; Lee, Hwaseob; Chang, Lorry; Wang, Feifan; Wu, Darren; Xiao, Yahui; Sun, Boshu; Ullah, Kaleem; Booksh, Karl; Wu, Wenzhuo; Gu, TingyiTwo-dimensional (2D) materials with unique physicochemical properties promote photocatalytic activities. As the 2D material composites research studies the statistical average of complex catalytic behaviors, an integrated photonic platform allows for clean and single flake level photo-catalytic investigations with precisely quantified photocatalytic activities. In this paper, fluence-dependent photo-oxidation in two-dimensional Tellurene (2D Te) is tracked by the evanescently coupled micro-resonator. Nearly 32% of oxidation is achieved in ≈10 nm 2D Te flake, compared to only 4.5% oxidation in a 30 nm sample, probed by the resonance shift in silicon micro-ring resonators substrate. The wider bandgap in the few layers of 2D Te allows faster charge transfer to adsorbed oxygen for a more efficient photocatalytic redox reaction. The photo-oxidation in hybrid 2D Te results in invariant lineshapes of optical transmission resonance for wavelength trimming (more than 3× resonance bandwidth). The low threshold power, near-infrared, and in-waveguide resonance trimming scheme is compatible with most integrated photonic setups for easy fixing of the nanofabrication-induced random resonance deviation for integrated photonic circuit applications in wavelength-division-multiplexing systems and spin qubits quantum computing.