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Abstract
In order to produce future optical integrated circuits, individual devices need to overcome the diffraction limit of light, which imposes a lower bound on the size limit of optical devices. Plasmonics, which describes light propagation on metal-dielectric interfaces, can be a route to produce very compact optical devices.
In this thesis, plasmonic devices on a fiber platform are analyzed: from coupling of light into optical fiber by using nanojets to use fibers to drive nano-antennas, a wide range of devices mixing plasmonics and optical fibers are studied.
To be more specific, the properties of the photonic nanojets are firstly studied for different concentrators: it is shown that an adequate choice of geometric shape and material can lead to an improvement of the electric field enhancement capacity of nanojets by a factor of 40%. The dynamics of the nanojet properties are also controlled by the magneto-optical effect (MOE).
Secondly, optical fiber based plasmonic devices are studied: a polarizer based on surface plasmon resonance on a PCF is analyzed. The device allows one state of polarization (e.g. y-polarized mode with losses of 1.6 dB/cm) to propagate through the fiber while the other state (x-polarized mode with losses of 1221 dB/cm) is heavily attenuated. In addition, a broadband and compact polarization splitter based on gold filled dual-core PCF is proposed that can work from 1420 nm to 1980 nm (560 nm bandwidth) with an extinction ratio (ER)<-20 dB and a total length of 254.6 micro meter.
Finally, plasmonic nano-antennas are integrated on optical fibers: the integration initially begins with an array of 80 plasmonic Yagi-Uda nano-antennas on the cladding of an optical fiber and it is shown that the signal reaching the fast detector can be increased by a factor of 5 dB by positioning these nano-antennas on the fiber cladding. Secondly, a new and flexible approach is proposed to control the electric field enhancement of bow-tie nano-antennas by integrating them on the lateral of a tapered optical fiber. The performance of the fabricated nano-antennas array in a quartz slide is tested by a Surface Enhanced Raman Scattering (SERS) experiment. A refractive index sensing experiment is also performed and a sensitivity of (240+/-30) nm/RIU is found in the 1.33-1.35 index range.