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Studies Of Some Cavity-based Devices Based On Photonic Crystals And Spoof Surface Plasmons

Posted on:2016-08-07Degree:DoctorType:Dissertation
Country:ChinaCandidate:X C GeFull Text:PDF
GTID:1108330464454337Subject:Optical Engineering
Abstract/Summary:Request the full-text of this thesis
Photonic crystals are periodic subwavelength dielectric structures, which can control the mo-tion and behaviour of photons in a similar fashion as the semiconductor crystals controlling elec-trons. Spoof surface plasmon is the analog of plasmonics in terahertz and microwave regions where plasmonic materials are not available. Both being periodic subwavelength structures, they can be used to create devices with extraodrinary properties. In this thesis several novel cavity-based de-vices utilizing photonic crystals in the optical region and spoof plasmons in the microwave region are studied both theoretically and experimentally.Numerical methods for simulating the properties of photonic crystals such as the plane wave expansion method and the finite-difference time domain method are introduced. Nanofabrication techniques are essential for realizing the subwavelength features of photonic crystal devices in the visible and near infrared wavelengths. A walkthrough of the silicon based fabrication procedure is introduced with the discussion of the proximity effect correction, which is crucial for fabricating photonic crystals, and some techniques in wet etching, which contributes to suspended structures for sensing applications.Hybrid spoof plasmonic and photonic crystal structures are designed to realize negative ef-fective indices. Followed by the design and experimental realization of an open cavity, which was previously proposed as a demonstration of the property of negative index materials. A large por-tion of the resonant mode in the open cavity overlaps with the environment thus it has potential applications in sensing or lasing. The open cavity demonstrated in this thesis works in the mi-crowave region but the principle could be transferred to the terahertz region and possible methods for realizing open cavities in the optical domain have also been discussed.The add/drop filter is an essential component for the wavelength-divided multiplexing. A compact drop filter is designed with coupled photonic crystal nanobeam microcavities based on the tunneling effect of degenerated modes. An experimental demonstration is made to show the proposed device has a reasonable performance, low loss and an ultracompact size. In addition to that, compared with widely used microring resonators. The proposed device is not limited by the free spectral range.Slow light waveguides can greatly reduce the group velocity of the propagating modes, thus enhance light-matter interactions. It can also be used to confine light with tapered structures to create microcavities. A microcavity refractive index sensor based on slow light waveguides with negative refractive index photonic crystals is proposed and experiementally fabricated. A sensitiv-ity of 770 nm/RIU is achieved by numerical simulation.
Keywords/Search Tags:photonic crystal, spoof plasmon, negative refraction, cavity, sensor, coupler
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