Research On The Photonic Crystal Fiber Based Plasmonic Sensing Mechanism And Its Technique

Recently, the Photonic Crystal Fibers(PCFs) have beening paving a new way towardsclosed-form all-in-fiber surface plasmon resonance(SPR) sensors with excellent performance.They have made full use of the naturally existed air holes in the PCF, and its designflexibility and diversity, as well as the high sensitivity of the SPR sensing technique. Theyhave provided a perfect solution to the phase matching condition and packaging issues whichexist in the traditional fiber optic SPR sensors.The work is supported by the international collaborative project between China andSingapore which entitled “Research on the microstructured optical fiber endoscopic sensingtechnique for detecting the digestive tract diseases”. The dissertation aims at the study on thenew sensing mechanism and implementation method of the nano photonic devices based onthe SPR effect. The research on the PCF-SPR sensing technique’s novel mechanism andphenomenon, and the development of functional SPR sensors has got the followingachievements:Firstly, a multi-core holey fiber based plasmonic sensor with large detection range andhigh linearity is proposed, and the new coupling mechanism of incomplete coupling underthe loss matching condition in the PCF-SPR sensing scheme is found for the first time. Theincomplete coupling under the phase matching condition and complete coupling under theloss matching condition coexist in the proposed design. The coupling transforms fromincomplete coupling to complete coupling with increasing analyte refractive index (RI),which has been explained by the coupled mode theory.Secondly, a liquid-core holey fiber based SPR RI sensor is designed, and a newphenomenon that the coexistence of positive and negative RI sensitivity is found. In thenovel design, not only the plasmonic mode dispersion relation but also the fundamentalmode dispersion relation is rather sensitive to the analyte RI. The significant advantage is towork in a large dynamic RI range within the limited optical source bandwidth, thus thespectrum utilization efficiency is improved and the experimental cost can be reducedsignificantly.Thirdly, a highly sensitive dual channel SPR sensor based on the holey fiber is presented.The higher order plasmonic resonance peak of the fundamental mode has been suppressed effectively, and the high channel independence and stability are obtained. There are threeoperation modes of the proposed functional SPR sensor, i.e., self-referencing sensing, multianalyte detecting and linear calibration sensing, which has the advantage of eliminate theenvironmental noise, high sensitivity and integration.These achievements are helpful to develop novel microstructured optical fiberendoscopic sensors, they also have great applications in the area of medical diagnostics, foodsafety control and environmental control.