Investigation of nanophotonic structures for imaging and sensing

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dc.contributor.advisorYu, Miaoen_US
dc.contributor.authorZHANG, ZHIJIANen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2017-06-22T05:56:42Z
dc.date.available2017-06-22T05:56:42Z
dc.date.issued2017en_US
dc.description.abstractThe ability to image micro/nano scale objectives with miniaturized optical components has always been of great interest due to its great potential in applications such as microscopy, nanofabrication, and biomedical monitoring. However, in traditional practice using dielectric lenses, the focal size is inevitably limited by the Abbe’s diffraction limit (0.51fλ/ρ). Here, λ is the wavelength in vacuum, and f and ρ are the focal length and the radius of the lens, respectively. Moreover, the performance of conventional spherical lenses deteriorates as their sizes approach the wavelength. On the other hand, owing to the recent advances in micro/nano fabrication techniques, miniature sensors have received much attention, which are highly desirable in many sensing applications for physical, chemical, and biomedical parameter measurements. However, the performance of miniature sensors usually suffers from the similar difficulty as miniaturized imaging systems. Recently nanophotonic structures have been explored for the development of miniaturizing imaging and sensing systems due to their capability of confining and manipulating light at a subwavelength scale. In this dissertation work, several different mechanisms that nanophotonic structures can be used to help enhance the performance of imaging and sensing in miniaturized systems are investigated. First, plasmonic lens utilizing the nanophotonic structure to achieve the subwavelength focusing ability is studied. Three different regions in the plasmonic lens design are defined. Furthermore, a plasmonic lens in the Fresnel’s region is designed and k.ed to achieve a sub-diffraction limit focus. Second, radially polarized light generated by the TEM mode in the annular aperture in metal is investigated, which can further enhance the focusing ability. Third, in terms of sensing, an ultra-thin plasmonic interferometer constructed with a nano-hole array is fabricated on a fiber facet. By using this structure, the multi-parameter sensing capability of this interferometer is demonstrated; high sensitivity refractive index and temperature sensing are achieved. Finally, a novel sensor design based on the cladding modes and buffer modes generated by the planar grating on the fiber facet is proposed. Experimental studies of this sensor demonstrate its superior temperature sensitivity and the potential of multi-parameter sensing.en_US
dc.identifierhttps://doi.org/10.13016/M20K3N
dc.identifier.urihttp://hdl.handle.net/1903/19368
dc.language.isoenen_US
dc.subject.pqcontrolledEngineeringen_US
dc.subject.pqcontrolledOpticsen_US
dc.subject.pquncontrolledImagingen_US
dc.subject.pquncontrolledMiniaturizationen_US
dc.subject.pquncontrolledMultiparameter sensingen_US
dc.subject.pquncontrolledNanophotonicsen_US
dc.subject.pquncontrolledOptic fiberen_US
dc.subject.pquncontrolledPlasmonicsen_US
dc.titleInvestigation of nanophotonic structures for imaging and sensingen_US
dc.typeDissertationen_US

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