Design And Characteristics Of Broadband Waveplates Based On Surface Plasmonic Subwevelength Structure

Controlling and manipulating polarization state of light is crucial in all opticalresearch and applications. Conventional component to manipulate polarization of light isthe birefringent bulky dichotic crystals in which two different refractive indexes along twoorthogonal optical axes resulting in a phase difference between the two directions, whichchanges the state of polarization.Recently, sub-wavelength nanoscale metallic devices attract increasing interests as amean to control the interactions between light and metallic micro-structure. In this thesis,theory and design of surface plasmonic waveplates based on subwavelength structure andsurface plasmon polariton is investigated, the major work are as follows:A broadband quarter-wave plate using an ultrathin metal film with patternedsubwavelength rectangular annular arrays (RAA) on a glass substrateis proposed andpresented. It is found that by manipulating asymmetric width of the annular gaps along twoorthogonal directions and resonant cavity effect, the amplitude and phase of the twoorthogonal electrical components can be well controlled. Quarter-wave plates working ontransmission mode at wavelength of1.55m has been realized through optimized designs,in which the phase difference variation is less than2%of/2between the two orthogonalcomponents can be obtained in an ultra-wide wavelength range of about110nm.A broadband quarter-wave plate working in reflective modeis further investigated.Combining the effects of surface plasmon polariton and micro cavity, a reflective surfaceplasmonic waveplate is realized withthe phase difference variation being less than2%of/2between the two orthogonal components in an ultra-wide wavelength range of about130nm. It provides a great potential for applications in advanced nanophotonic devices andintegrated photonic systems.