Plasmonic Photonic Crystal Fibers

Surface plasmon waves are coupled electron–photon modes at the metal–dielectric interface. They can significantly enhance light–matter interactions that are favorable in many applications including nanophotonics, data storage, microscopy, solar cells, and sensing. Compared with the prism-based coupling configuration, optical fiber-based plasmonic devices offer more compact and robust configuration for exciting the plasmon modes. Photonic crystal fibers (PCFs) are a special class of optical fibers in which the presence of holey structures or periodic microstructures of refractive index modulations can provide a wide scope of flexibility in the control and engineering of the optical properties, thus opening up the potential for many new applications and scientific explorations. Notably, PCFs are a desirable platform to incorporate plasmonic structures for the excitation of surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR). Three main types of plasmonic PCF structures have been developed and reported in the literature, including metal nano-/microwire-filled plasmonic PCF, metal-coated plasmonic PCF, and nanoparticle-deposited/filled plasmonic PCF. This chapter provides a comprehensive review on the recent progress of these reported plasmonic PCF structures in terms of design and applications. Firstly, the operating principles based on surface plasmon polaritons and localized surface plasmon polaritons are presented. Secondly, the experimental studies of plasmonic PCF structures for various application areas are reviewed, including refractive index sensing, biosensing, temperature sensing, polarization, and birefringent devices. Lastly, design considerations and challenges are discussed.