RESUMEN
In this paper we present all-in fiber tunable devices based on specially designed and optimized high-index photonic crystal fibers filled with nematic liquid crystals. A special host microstructured optical fibers have been designed and manufactured to ensure low-loss index guiding and mode field diameter matching to SMF-28 fiber, ensuring low losses on interconnections with leading in-out FC/PC connectorized pigtails. We present four types of tunable all-fiber devices: tunable retarders with tuning range as high as 20 λ, tunable polarizers with variable axis of polarization and continuously tunable polarization dependent losses, tunable and fully controllable polarization controller and finally indeterministic depolarizer in which depolarization is caused by random thermodynamic process. We also present a cost-effective method to achieve change in the direction of the steering electric field, which was controlled by custom-made programable controllers. Finally, we present a method for effective packaging for the proposed devices.
RESUMEN
A micro-ring resonator structure was fabricated via the two-photon polymerization technique directly on a single-mode fiber tip and tested for refractive index sensing application. The micro-ring structure was used to excite whispering-gallery modes, and observations of the changes in the resonance spectrum introduced by changes in the refractive index of the environment served as the sensing principle. The proposed structure has the advantages of a very simple design, allowing for measurements in reflection mode, relatively easy and fast fabrication and integration with a single tip of a standard single-mode fiber, which allowed for quick and convenient measurements in the optical setup. The performance of the structure was characterized, and the resonant spectrum giving high potential for refractive index sensing was measured. Future perspectives of the research are addressed.