Fabrication of plasmonic sensors and photonic crystals patterns by colloidal lithography

Abstract

In Chapter 2, I present a simple and effective fabrication approach for the novel gold nanohole arrays that can be tuned over wide spectral range from visible to near-infrared by simply varying the geometric parameters. The strong plasmon resonance causing from plasmon coupling between the brims of the nanoholes in the top gold films and the bottom gold disks were thoroughly investigated by 3D computation analysis (FDTD). Comparison of the maesured reflectance spectrum with that calculated by FDTD method showed a very good consistency. In addition, we demonstrate a novel optofluidic platform which has built-in subwavelength nanohole arrays exhibiting the strong plasmon resonances within microfluidic chips. The modulation of plasmon resonances for various liquid flows was confirmed by changes of the dip position of the reflectance spectra from visible to near-infrared range. Therefore, the subwavelength gold nanohole arrays integrated within microfluidic chip are highly fascinating for application where strong plasmon enhancement is needed and have potential for optofluidic label-free chemical and biomolecular sensors. In Chapter 3, I have demonstrated that composite and porous microparticles with photonic bandgaps can be fabricated via a simple and controllable method by combining self-assembly of colloidal particles and photolithography techniques. Periodic nanostructures formed by the colloidal crystals gave rise to a photonic bandgap in the photoresist film, and photolithography enabled creation of tailored microparticles. For this, the deposition and embedding of the colloidal crystals into SU-8 photoresist film was performed by dip coating method and capillary wetting of polymeric film on the particle surface, respectively. Subsequent photolithography and dissolution of the sacrificial layer produced 2D microparticles with the desired shape. These particles contained a periodic nanostructure at the scale of half wavelength of interacting light. It should b...