Abstract
Plasmonics and photonics have received intensive attention in both academic and industrial communities due to their extensive applications. Optical sensing has been identified as one of the most promising applications for plasmonic and photonic technology, which has been widely employed in chemical analysis, environmental monitoring, biological detection, security, and food safety. A wide range of plasmonic and photonic structures and sensing mechanisms have been proposed and demonstrated over the past few decades [J4]. Highly sensitive and accurate optical sensors with plasmonic and photonic structures are being vigorously pursued by using new materials and new sensingmechanisms due to their unique properties. In this thesis, various plasmonic and photonic sensors are theoretically investigated and compared. The first type of optical sensors is two-dimensional (2D) materials integrated surface plasmon resonance (SPR) sensors. A highlysensitive and accurate near-infrared SPR refractive index (RI) sensor based on MoS2-on-Al structure was proposed [J7,C6,C7]. The effect of Al thickness, number of MoS2 layers, and the analyte RI on the sensor performance was investigated. A design of a TMDCs mediated long range SPR (LRSPR) sensor with a significantly improved sensor performance (higher sensitivity and detection accuracy) as compared to the conventional SPR sensors was studied [J6,C4,C5]. The sensitivity of conventional SPR sensor is also significantly improved with the combination of 2D MXene and TMDCs [J5]. iii The second optical sensor studied is an ultrasensitive temperature sensor based on the SPR enhanced composite Goos-Hänchen shift (GHS) and Imbert-Fedorov shift (IFS), a mixture of spatial and angular GHSs and IFSs, respectively[J1,C3]. The spatial and angular GHSs and IFSs of p-polarized incident light are significantly enhanced around the resonant angle of SPR. The ultrahigh temperature sensitivity of 0.79 cm/K and 188 µm/K are obtained with the composite GHS and IFS, respectively, which are 6 orders higher than that obtained with a bare Au surface. The third type of optical sensors is a room temperature surface exciton polariton(SEP) sensor, which was realized by replacing the metal thin film in Kretschmann-Raether configuration of surface plasmon polariton (SPP) with a J-aggregate cyanine dye film [J3,C2]. The excitation of SEP results in a strong electric field at the sensor surface and exponentially decays into the analyte, which is sensitive to the ambient RI variations. The proposed SEP sensor exhibits both higher bulk and surface sensitivities than the conventional Au-based SPP sensor. Finally, the SEP enhanced spatial and angular GHSs and IFSs are theoretically investigated [J2,C1]. The spatial and angular shifts for the TM polarized incident light are strongly enhanced around the resonant angle with the excitation of SEP. A highly sensitive gas sensor based on the SEP enhanced GHS or IFS is proposed, which exhibits the maximum RI sensitivity of 6.27 ? 108 nm/RIU (RIU: refractive index unit) and 7.28 ? 108 nm/RIU, respectively. The designed plasmonic and photonic sensors in this thesis not only contribute to the understanding of plasmonic and photonic phenomena (e.g., SPR, LRSPR, SEP, GHS and IFS), but also provide potential applications in temperature sensing, chemical sensing, and biosensing. The proposed optical sensors based on SEP and SEP enhanced GHS (IFS) will also enrich the sensing mechanisms of plasmonic and photonic sensors. Note the fabrication techniques of these proposed plasmonic and photonic sensors studied in this thesis are readily to be realized experimentally for future applications.