Plasmonic Nanophotonic Structures And Fiber-end Integration

Nanophotonic structures have broad application potentials in optoelectronic techniques and have attracted extensive research interests.Plasmonic photonic nanostructuring on the end facets of optical fibers is an effective way to extend the related functions,realize integration of the involved photonic devices,and obtain novel fiber sensors.Fabrication of plasmonic photonic structures with high quality,low costs,and large effective areas,as well as their subsequent transfer onto fiber tips,is of significant importance for nanophotonics and the related applications.This thesis mainly included the following research results:(1)A flexible transfer technique is introduced for the simple,efficient,and highquality fabrication of plasmonic photonic nanostructures on the fiber end facets.A gold nanowire grating was first fabricated on a large-area planar glass substrate deposited with an ITO film.This provides a large space for reducing fabrication challenges,improving the fabrication qualities,and achieving a high success rate.Then,a PMMA film was spin-coated onto the top surface of the gold nanowire grating,which was employed as a buffer connection layer.On this basis,the whole sample was immersed into hydrochloric acid and the grating structure connected by the PMMA film was removed from the glass substrate,after ITO layer was completely etched off.In the last stage,The lift-off gold nanowire grating was picked up,cleaned,and transferred to capping the fiber end.In the last stage,the fiber tip was annealed at 500 ?C to fix the gold nanowires solidly,finishing the fabrication procedures.Apparently,this fabrication method is low-cost technique with high quality,high reproducibility,and high success rate,which supplies a new approach for the development of refractive index sensors and ultrafast optical switching.(2)An ultrafast optical switching device is achieved,making use of an overlap between optical resonance modes in a waveguided gold nanowire grating.Gold nanowires as thick as 220 nm were produced using interference lithography,colloidal gold nanoparticles,and annealing processes.A mutually enhanced interaction was discovered between the waveguide resonance mode and the distributed feedback microcavity resonance mode,so that an optical extinction as large as 96 % was observed.Using such an effect,an efficient optical switch was achieved with a modulation depth of 16.7 %,a bandwidth of smaller than 15 nm,a response speed of 290 fs,and a signal contrast larger than 95 %.