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- ItemSelective Out‐of‐Plane Optical Coupling between Vertical and Planar Microrings in a 3D Configuration(Hoboken, NJ : Wiley, 2020) Valligatla, Sreeramulu; Wang, Jiawei; Madani, Abbas; Naz, Ehsan Saei Ghareh; Hao, Qi; Saggau, Christian Niclaas; Yin, Yin; Ma, Libo; Schmidt, Oliver G.3D photonic integrated circuits are expected to play a key role in future optoelectronics with efficient signal transfer between photonic layers. Here, the optical coupling of tubular microcavities, supporting resonances in a vertical plane, with planar microrings, accommodating in‐plane resonances, is explored. In such a 3D coupled composite system with largely mismatched cavity sizes, periodic mode splitting and resonant mode shifts are observed due to mode‐selective interactions. The axial direction of the microtube cavity provides additional design freedom for selective mode coupling, which is achieved by carefully adjusting the axial displacement between the microtube and the microring. The spectral anticrossing behavior is caused by strong coupling in this composite optical system and is excellently reproduced by numerical modeling. Interfacing tubular microcavities with planar microrings is a promising approach toward interlayer light transfer with added optical functionality in 3D photonic systems.
- ItemPerovskite Origami for Programmable Microtube Lasing(Weinheim : Wiley-VCH, 2021) Dong, Haiyun; Saggau, Christian Niclaas; Zhu, Minshen; Liang, Jie; Duan, Shengkai; Wang, Xiaoyu; Tang, Hongmei; Yin, Yin; Wang, Xiaoxia; Wang, Jiawei; Zhang, Chunhuan; Zhao, Yong Sheng; Ma, Libo; Schmidt, Oliver G.Metal halide perovskites are promising materials for optoelectronic and photonic applications ranging from photovoltaics to laser devices. However, current perovskite devices are constrained to simple low-dimensional structures suffering from limited design freedom and holding up performance improvement and functionality upgrades. Here, a micro-origami technique is developed to program 3D perovskite microarchitectures toward a new type of microcavity laser. The design flexibility in 3D supports not only outstanding laser performance such as low threshold, tunable output, and high stability but also yields new functionalities like 3D confined mode lasing and directional emission in, for example, laser “array-in-array” systems. The results represent a significant step forward toward programmable microarchitectures that take perovskite optoelectronics and photonics into the 3D era. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.
- ItemRecent Progress on Optoplasmonic Whispering-Gallery-Mode Microcavities(Weinheim : Wiley-VCH, 2021) Chen, Yongpeng; Yin, Yin; Ma, Libo; Schmidt, Oliver G.Optoplasmonic whispering-gallery-mode (WGM) microcavities, consisting of plasmonic nanostructures and optical microcavities, provide excellent platforms for exploring fundamental mechanisms as well as facilitating novel optoplasmonic applications. These integrated systems support hybrid modes with both subwavelength mode confinement and high-quality factor which do not exist in either pure optical WGM microcavities or plasmonic resonators. In this progress report, geometric designs and fabrication strategies of optoplasmonic microcavities, which efficiently bridge the interaction between resonant light and plasmonic resonances, are reviewed in detail. Three types of hybrid modes in the optoplasmonic microcavities, that is, surface-plasmon-polariton whispering-gallery modes, hybrid photon–plasmon whispering-gallery modes, and heterostructured metal–dielectric whispering-gallery modes, are considered. These modes are characterized by a largely enhanced evanescent field that is referred to as a plasmon-type field in hybrid whispering-gallery modes. Moreover, the coupling effect between localized surface plasmon resonances and whispering-gallery modes is summarized. The underlying coupling mechanisms and their influence on mode shifts, Q factor, mode splitting, and line shapes of the whispering-gallery modes are discussed. Applications based on optoplasmonic WGM microcavities including enhanced sensing, nanolasing, and free-space coupling are highlighted, followed by an outlook of the opportunities and challenges in developing large-scale on-chip integrated optoplasmonic systems.
- ItemImperceptible Supercapacitors with High Area-Specific Capacitance(Weinheim : Wiley-VCH, 2021) Ge, Jin; Zhu, Minshen; Eisner, Eric; Yin, Yin; Dong, Haiyun; Karnaushenko, Dmitriy D.; Karnaushenko, Daniil; Zhu, Feng; Ma, Libo; Schmidt, Oliver G.Imperceptible electronics will make next-generation healthcare and biomedical systems thinner, lighter, and more flexible. While other components are thoroughly investigated, imperceptible energy storage devices lag behind because the decrease of thickness impairs the area-specific energy density. Imperceptible supercapacitors with high area-specific capacitance based on reduced graphene oxide/polyaniline (RGO/PANI) composite electrodes and polyvinyl alcohol (PVA)/H2SO4 gel electrolyte are reported. Two strategies to realize a supercapacitor with a total device thickness of 5 µm—including substrate, electrode, and electrolyte—and an area-specific capacitance of 36 mF cm−2 simultaneously are implemented. First, the void volume of the RGO/PANI electrodes through mechanical compression is reduced, which decreases the thickness by 83% while retaining 89% of the capacitance. Second, the PVA-to-H2SO4 mass ratio is decreased to 1:4.5, which improves the ion conductivity by 5000% compared to the commonly used PVA/H2SO4 gel. Both advantages enable a 2 µm-thick gel electrolyte for planar interdigital supercapacitors. The impressive electromechanical stability of the imperceptible supercapacitors by wrinkling the substrate to produce folds with radii of 6 µm or less is demonstrated. The supercapacitors will be meaningful energy storage modules for future self-powered imperceptible electronics.