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Interference and Diffraction
Published in Toyohiko Yatagai, Fourier Theory in Optics and Optical Information Processing, 2022
The wave expands on a screen located far from the aperture, which is illuminated by a coherent light. The diffraction is an optical phenomenon of the wave propagation after an obstacle such as an aperture, where the wave propagates with some divergence. To define the extent of the diffraction pattern, we consider the distance from the center of the diffraction pattern to the first zero intensity, kdθ2=π.
Surface plasmon resonance (SPR)-based D-shaped photonic crystal fiber polarization filter and refractive index sensor with a hexagonal pore structure
Published in Instrumentation Science & Technology, 2022
Jian Huang, Dan Yang, Geng Lv, Zhulin Wei, Tonglei Cheng
Photonic crystal fibers (PCFs) are known as porous or microstructured fibers. In contrast to ordinary optical fibers, PCFs have distinctive optical attributes, such as ultra-high nonlinearity, an endless single-mode, large mode area, and flat dispersion.[1–4] Nowadays, various new methods and technologies, including modifying the arrangement of pores, injecting liquid into particular pores and plating metal film, have been applied to PCFs.[5–7] In particular, combined with the excellent optical properties of PCFs and surface plasmon resonance, novel devices have emerged. Surface plasmon resonance (SPR) is an optical phenomenon that occurs at the interface between dielectric and metal, caused by the absorption of incoming light by plasma on a heavy metal membrane.[8] It is susceptible to changes in the permittivity of the metal and dielectric as well as the shape of the structure. Due to the high sensitivity of SPR and the small size of PCF, these devices are widely used in environmental monitoring, medical medicine, biochemical sensing and many other fields.[9–12]
Ultra-sensitive hexagonal PCF-SPR sensor with a broad detection range
Published in Journal of Modern Optics, 2020
Wei Liu, Chunjie Hu, Lei Zhou, Zao Yi, Chao Liu, Jingwei Lv, Lin Yang, Paul K. Chu
Surface plasmon resonance (SPR) is an optical phenomenon arising from resonance excitation of free electron oscillations at the metal–dielectric interface upon p-polarized light radiation and subsequent propagation of the surface plasmon wave (SPW) along the metal–dielectric interface [1–3]. In the optical industry, This SPR technology has been applied to optical absorbers [4,5], fibre sensors [6,7], optical polarizers [8], and other optical devices. In SPR, the environment influences the trapped electromagnetic wave as well as coupling conditions. For instance, the SPR wavelength shifts as the refractive index (RI) of the surrounding medium changes [9–11] thus providing the capability of fast and real-time detection and label-free monitoring [12,13]. Hence, SPR techniques have received attention in other fields covering genomics, proteomics, drug screening, environmental monitoring, food quality control, and medical diagnostics [14–16]. As is well-known, the traditional SPR-RI sensors are based on prism coupling [17] but suffer from the bulky structure. In order to miniaturize the structure, some RI sensors are based on fibre-coupled SPR [18]. However, in spite of the reduced size, the coupling efficiency of the fundamental mode and surface plasmon polariton (SPP) mode is relatively poor. Recently, photonic crystal fibre (PCF) sensors have attracted much interest attributing to the wide range, large mode area, high sensitivity, and flexible structure [19,20].
Applications and challenges of elemental sulfur, nanosulfur, polymeric sulfur, sulfur composites, and plasmonic nanostructures
Published in Critical Reviews in Environmental Science and Technology, 2019
Yong Teng, Qixing Zhou, Peng Gao
Plasmons have been explored as a surface-wave optical phenomenon (an electromagnetic wave of charge density fluctuations on the surface) known for more than 150 years (Figure 7) (West et al., 2010; Naik, Shalaev, & Boltasseva, 2013), which are created by the resonant interaction between surface electron-charged oscillations and the electromagnetic field of the light (Ozbay, 2006). Surface plasmons can couple light strongly to the material surface, leading to the confinement of light in an area smaller than that predicted by the diffraction limit and the enhancement of local electromagnetic fields intensity (Naik et al., 2013). The properties of plasmonic nanostructures derive from the collective electron excitations (Schuller et al., 2010), and are defined and controlled by the size and shape of nanostructures (Rycenga et al., 2011) making it possible to engineer their electric and magnetic responses over a broad range (Fan et al., 2010). Light can be focused and guided down to the nanometer-length scale by plasmonic nanostructure and manipulated through tailoring the size, shape, and environment of the nanostructure. The plasmonic modes include the localized surface plasmons (LSPs) and propagating surface plasmons (PSPs), which are primarily limited by the size of the plasmonic structure that supports them (Rycenga et al., 2011).