On chip optical sensing

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Optical Properties and Optoelectronic Applications of Nano-size Metallic Films and Metamaterials.

Future optical and optoelectronic devices are desired to have compact sizes, high efficiencies, robust performance, and low manufacturing costs. All these advances demand developments both in their constituent materials and design concepts. Silver (Ag) is one of the most widely used materials for optoelectronic devices and metamaterials. However, Ag is well known to have several issues, including difficulty to form high-quality thin films, poor stability in an ambient environment and under elevated temperatures, and inferior adhesion with substrates. In light of this, a new kind of silver: doped silver is developed. With the aid of a small amount of doping elements during the Ag deposition, ultra-thin, smooth, and low-loss Ag films are obtained. Compared to pure Ag films, doped Ag films have a significantly improved long-term and thermal stability, as well as good adhesion to various substrates. Doped Ag films have facilitated diverse high-performance optical and optoelectronic devices, such as organic solar cells, organic light emitting diodes, optical metamaterials, and plasmonic devices. Metamaterials are artificially designed materials with extraordinary optical properties. Nano-size metamaterials (metasurfaces) are demonstrated for controlling various properties of light. An asymmetric light transmitting metasurface consisting of coupled metallic sheets is demonstrated. It has a measured transmission efficiency of 80%, extinction ratio of 13.8 dB around 1.5 µm, and a full width half maximum bandwidth of 1.7 µm. It is as thin as 290 nm, has good performance tolerance against the angle of incidence and constituent nano-structure geometry variations. In addition, a large-area, printed metasurface is designed and fabricated. It is made of lossless dielectric (silicon) materials and offers the functionality of converting a linearly polarized incident light into a radially polarized transmitted light. These optical and optoelectronic devices also provide valuable solutions to problems in other fields, such as acoustic wave detection. It is shown that optical resonant structures provide a unique approach for acoustic wave detection. Nanoimprinted polymer microring resonators are investigated as high-performance ultrasound detectors. To further reduce the detector size, polymer filled silicon metasurfaces on fiber tips are also designed and fabricated.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133414/1/chengzh_1.pd

InP 導波路に結合した高 Q 値微小金属クラッド共振器の設計と作製

学位の種別: 修士University of Tokyo(東京大学

Strong optical coupling between 3D confined resonant modes in microtube cavities

Coupled whispering-gallery-mode (WGM) optical microcavities have been extensively explored to tune the resonant eigenfrequencies and spatial distributions of the optical modes, finding many unique photonic applications in a variety of fields, such as nonlinear optics, laser physics, and non-Hermitian photonics. As one type of WGM microcavities, microtube cavities with axial potential wells support 3D confined resonances by circulating light along the microtube cross-section and axis simultaneously, which offers a promising possibility to explore multidimensional and multichannel optical coupling. In this thesis, the optical coupling of 3D confined resonant modes is investigated in coupled microtube cavities fabricated by self-rolling of prestrained nanomembranes. In the first coupling system, multiple sets of 3D optical modes are generated in a single microtube cavity owing to nanogap induced resonant trajectory splitting. The large overlap of optical fields in the split resonant trajectories triggers strong optical coupling of the 3D confined resonant modes. The spectra anticrossing feature and changing-over of one group of coupled fundamental modes are demonstrated as direct evidence of strong coupling. The spatial optical field distribution of 3D coupling modes was experimentally mapped upon the strong coupling regime, which allows direct observation of the energy transfer process between two hybrid states. Numerical calculations based on a quasi-potential model and the mode detuning process are in excellent agreement with the experimental results. On this basis, monolithically integrated twin microtube cavities are proposed to achieve the collective coupling of two sets of 3D optical modes. Owing to the aligned twin geometries, two sets of 3D optical modes in twin microtubes are spectrally and spatially matched, by which both the fundamental and higher-order axial modes are respectively coupled with each other. Multiple groups of the coupling modes provide multiple effective channels for energy exchange between coupled microcavities, which are illustrated by the measured spatial optical field distributions. The spectral anticrossing and changing-over features of each group of coupled modes are revealed in experiments and calculations, indicating the occurrence of strong coupling. In addition, the simulated 3D mode profiles of twin microcavities confirm the collective strong coupling behavior, which is in good agreement with the experimental results. Our work provides a compact and robust scheme for realizing 3D optical coupling, which is of high interest for promising applications such as 3D non-Hermitian systems and multi-channel optical signal processing

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community