This PDF file contains the front matter associated with SPIE Proceedings Volume 11608 including the Title Page, Copyright information, and Table of Contents.

Surface plasmon (SP) is widely used in biosensing. There are generally two configurations for SP excitation: the prismcoupled and objective-coupled configurations. However, both configurations show limitations in SP excitation. We propose a non-spherical super-lens for SP excitation. It features on: 1) simple configuration without the aid of objectives; 2) allowing 2-D excitation; 3) low cost. We elaborate the design concept and the designed profile. To the best of our knowledge, this is the first time to propose this specific lens for SP excitation.

Plasmonic core-shell nanoparticles (CSNPs) have been extensively used as SERS active-substrates because their localized surface plasmonic resonance (LSPR) properties and thus the surface enhanced Raman scattering (SERS) activities can be regulated by changing the shell thickness. In this work, we selected Ag@MoS₂ CSNP with 40 nm radius of Ag as core and varied thickness of MoS₂ as shell to investigate the shell-dependent plasmonic behaviors including LSPR and SERS by using finite difference time domain (FDTD) simulations. The LSPR peak of Ag@MoS₂ CSNPs shows a broad red-shifting with an increasing shell thickness from 0 nm to 40 nm, giving rise to that the LSPR peak tunes from visible region (385 nm) to near infrared (NIR) region (1100 nm). The SERS activity of Ag@MoS₂ CSNP, represented by the enhancement of local electrical field (EM), can also be modulated by changing the shell thickness, and the optimal enhancement factor (EF) under 633 nm laser excitation is determined to be 3.54×10⁶ when the shell thickness is 4 nm. The wide-range LSPR tunability of Ag@MoS₂ CSNP provides enormous potential for NIR SERS application and enhanced photocatalytic activity

To discuss the effect of aluminum-doped zinc oxide (AZO）sine grating with a random rough surface on the absorption and reflectivity of thin film silicon solar cells. The random rough surface was expressed with Correlation length (Cor_ l) and Average height (Ave_ h), and superimposed on the one-dimensional AZO sine grating with 980 nm period and 160 nm groove height. Random rough surface AZO gratings were used as the front electrode of thin film silicon solar cells with 1000 nm silicon absorption layer thickness. Theoretical simulation results showed that the influence of Cor_ l on the reflectivity was smaller than that of Ave_ h. Moreover, high specular reflection acquired in the range of Cor_ l 0.011~0.015 and Ave_ h 0.2-0.8. When the Cor_ l was fixed, the diffuse reflection decreased with the increase of the Ave_ h. Results of the solar cell absorption showed that the thin film silicon solar cell with Ave_ h in the range of 0.2 ~ 0.8 had strong absorption at 440 ~ 500 nm, 575 ~ 710 nm, 740 ~ 755 nm and 795 ~ 815 nm wavelength band as the Cor_ l was 0.01. In the aspect of experiment fabrication, random rough surface AZO grating and smooth surface AZO grating was fabricated with wet etching and lift-off process respectively. It was suggested that as front electrode, random rough surface AZO grating with smaller Cor_ l and larger Ave_ h could suppress reflection and enhance absorption, so as to improve light trapping efficiency of the thin film silicon solar cells.

We numerically simulate the trapping properties of Rayleigh particles by using focused canonical vortex beam and noncanonical vortex beam. The effects of topological charge and phase distribution of optical vortex on trapping Rayleigh particles are discussed. The results show that when an optical vortex takes different values of topological charge, the focused canonical vortex beam has similar trapping properties of Rayleigh particles: the low refractive index particles can be trapped in two dimensions at the focal point, and the high refractive index particles can be fully stably trapped at a ring of the focal plane. However, when focused noncanonical vortex beam is used to trap Rayleigh particles, for different values of topological charge, the low refractive index particles can be trapped in two dimensions or three dimensions in the focal plane, and the high refractive index particles can be fully stably trapped at several points of the focal plane. Therefore, when focused vortex beam is used to trap Rayleigh particles, the trapping regions and the trapping stability of Rayleigh particles can be adjusted by changing the topologically charge and phase distribution of optical vortex.

In this paper, we proposed a multi-parameter sensing system based on a polarimetric multilongitudinal-mode fiber laser sensor and beat frequency signal interrogation technique. The polarimetric fiber laser consists two fiber Bragg gratings and a piece of Erbium-doped-fiber. Since the linear birefringence exists in any real fiber duo to its core deviating from a circular shape, two types of beat frequency signals exist in the fiber laser: longitudinal mode beat frequency and polarization mode beat frequency signals. They have different sensing characteristic to external perturbations such as temperature or strain change, so the polarimetric fiber laser can distinguish simultaneously the change of strain, temperature and the birefringence change. We theoretically analyzed the principle for measurement of temperature, strain and fiber birefringence, and experimentally studied the sensing performance of temperature, strain and fiber birefringence. The proposed multi-parameter sensing system just consists a polarimetric fiber laser sensor and a beat frequency demodulation equipment, so it shows the advantages of simple structure, portability, high sensitivity, and low cost.

Controlling the polarization state of light has important applications in optical communications, imaging, and detection. The latest developments in metamaterials can miniaturize optical components to the sub-wavelength range. The previous work cannot simultaneously take into account the two aspects of simple structure and high efficiency. Here, we propose a simple and effective circular polarization converter, which is composed of three layers of rotated gold split-rings and SiO2 substrate. It can convert LCP and RCP into orthogonally polarized light in two adjacent bands, with conversion efficiencies of 70% and 52%, respectively. Meanwhile, an asymmetric transmission of about 0.5 is achieved efficiently. The error caused by allowable changes of structural parameters will not affect the efficiency of asymmetric polarization conversion, indicating the high stability of our converter. As an ultra-thin planar optical element, the proposed metasurface can be used in integrated photonics, optical sensing and other fields. The asymmetric transmission in adjacent frequency bands may contribute to information encoding and decoding in applications of optical communication.

We propose and demonstrate a cascaded micro-ring structure based on silicon nitride to achieve on-chip signal detection and spectral reconstruction. The core of the system is eight rings with different radii. We have developed a mathematical algorithm based on convex optimization theory to achieve spectral reconstruction with a resolution of 0.08 nm and a bandwidth of 40 nm.

In this work, a high figure of merit (FOM) surface plasmon resonance (SPR) with bimetallic layer (Au/Ag) based on wavelength and angular combined interrogations approach is presented. To further addition the performance of the SPR sensor, the sum of the minimum reflectivity (R_min) is calculated with the refractive index interval of 0.004 as a step from 1.33 to 1.37 at first. Then, the performance of the sensor is analyzed for varying silver-gold thickness. Our simulations indicate that the proposed configuration for Kretschmann’s SPR sensor should be silver (48 nm)-gold (1 nm) for achieving the best FOM (about 150 RIU^-1).

Based on the Maxwell stress tensor method and the full wave simulations, we show that a lateral optical force (LOF) can be induced on a pair of spherical nanoparticles with different chiral combinations under the illumination of plane waves with the linear polarization either parallel or normal to the axis of the two nanospheres. It is demonstrated that the LOF can appear on each particle in the direction perpendicular to the particles' axis and the light propagation when either one or two particles have the chirality. Such an LOF can be tailored by both the magnitude and handedness of the particle chirality as well as the incident linear polarizations. Using the analytical expression of optical forces based on the dipole approximation, the physical origin of the LOF can be traced to many channels, including the gradient force, the radiation force, the curl force, and the spin force due to the inter-particle interaction mediated by the light. Our results might find applications in chiral discrimination such as chiral molecular and biological cells.

As an important parameter for evaluating optical devices, chromatic aberration is an enduring research hotspot in optics. The traditional bulk lens relies on the polished surface profile on the transparent optical material to achieve the required gradual phase change. Compared with the traditional lens, the metalens can achieve the effect of focusing the beam with a more suitable small size standard. In this paper, the geometric phase method is used to realize the phase shift required by the surface of the achromatic metalens through the unique design of the nano-unit column array. In order to be applied to the optical path of multi-wavelength phase microscopy imaging, the metalens designed in this paper effectively eliminates chromatic aberration in the visible light band from 500 nm to 595 nm and improves the imaging resolution. It also satisfy the needs of modern optical devices for ultra-light, ultra-thin and easy portability, and can be used in a variety of optical instruments, aerospace and military fields.

Fiber based optical coherence tomography (OCT), which is combined by OCT and fiber probe, presents advantages of high longitudinal resolution, flexibility and miniaturization structure. However, the depth of focus (DOF) and transverse resolution depended on OCT fiber probes are two constraining parameters. The realization of high transverse resolution imaging could result in the reduction in the effective imaging range. To address this issue, a focal length controllable fiber probe based on microcavity structure is proposed in this paper. A segment of alcohol-filled silica capillary is inserted between a single-mode fiber (SMF) and a section of gradient-index (GRIN) fiber and works as a beam expander. By adjusting the surrounding temperature, the expanding condition changes due to the alcohol refractive index is different, eventually the focal length of the probe can be tuned. Experimental results prove that the focal length can be tuned freely from ~1835 μm to ~1650 μm while the temperature of the alcohol is changed from 20°C to 60°C.

It is known that the particle chain can be served as a waveguide to guide the electromagnetic wave in the subwavelength scale and the metallic particle chain can only support the transverse electric (TE) mode (the magnetic field is perpendicular to the propagation direction). In this work, the composite metal-dielectric chains are constructed as the rod arrays in form of a straight line, a zigzag edge, or a combined double chains, in which both the TE mode and the transverse magnetic (TM) mode (the electric field is perpendicular to the propagation direction) can be supported. Based on the Mie theory and multiple scattering theory, the dispersion curves for different chains can obtained rigorously so that the dependence of the edge states on the structure parameters and symmetry of the chains can be examined. As a result, the loss can be reduced and the frequency of the surface plasmon polariton can be adjusted. In addition, the idea can be further extended to composite chains composed of the dielectric and magnetic particles so that the nonreciprocal features can be modulated.

The quarter wave plate applied to the extreme ultraviolet (EUV) region can realize the conversion of linear polarization and circular polarization EUV light source, so it has a wide range of applications such as magnetic microscopy techniques based on circularly polarized light. In this paper, a lineally chirped Mo/Si multilayer mirror is used to design a EUV quarter-wave plate. With the increasing thickness variation value of linearly chirped multilayer, the reflective phase delay between s- and p-polarized light increases at first and then realizes its maximum value. In this case, a quarter wave plate that can realize 90° phase delay can be designed by optimizing the structure parameters of a linearly chirped multilayer mirror. A linearly chirped Mo/Si multilayer which contains 13 pairs of bilayers with 14.7 nm central thickness and 1.94 nm thickness variation can achieve a reflective phase retardation of 89.95° at 90 eV under 30° grazing incidence. At the same time, the reflectivity of s- and p-polarized light are 47.65% and 10.09% respectively. The development of an EUV quarter wave plate based on a linearly chirped multilayer mirror could promote the research on the production and application of circularly polarized EUV light sources.

We present a method of phase modulation on the incident beam of the optical system to obtain a super-resolution focused spin spot by a multibelt binary optical phase element. We investigate the focusing properties of various structured lights from three situations: vortex beam, vector beam, and scalar beam, including the azimuthally polarized optical vortex beam (APOV), radially polarized beam (RP) and circularly polarized beam (CP). Under the same numerical aperture and the premise of ensuring the longitudinal uniformity of the focused field, we optimize the belt spacing of the multibelt binary optical phase element to obtain the optimal solution for each beam by the simulated annealing algorithm. The full-width at half-maximum (FWHM) of the focused spot of the APOV is the smallest. And the focused spot of the RP is second smallest. Particularly, the modulated focused APOV has an extremely small spin spot with pure transverse polarization. Its spin texture is similar to that of the Bloch-type magnetic skyrmion in the central region without the modulation. This kind of focused spin spot super the diffraction limit has potential in the applications of super-resolution imaging, circular dichroism imaging, chiral imaging, and the screening and manipulation of chiral particles.