This PDF file contains the front matter associated with SPIE Proceedings Volume 12961, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Zinc oxide (ZnO), a semiconductor material, has been widely explored due to its unique photoelectric properties. However, its application in photoelectric chemistry is limited by its fast recombination of excited electron-hole pairs and narrow wavelength range of light absorption. Here, we report a novel Ag-nanoparticle-decorated ZnO/ZnSe core-shell heterostructure, which greatly enhances the photoelectrochemical properties compared with pure ZnO. The nanocomposites, consisting of ZnO nanorods as the core and Ag-nanoparticle-decorated zinc selenide (ZnSe) as the shell, were synthesized via an improved low-temperature hydrothermal method combined with in-situ selenization-chemical vapor deposition and nanoparticle self-assembly techniques. The material presents a much higher photocurrent density than pure ZnO material with sub-millisecond response time and excellent stability. Our synthetic strategy may open up a new way to enhance photoelectrochemical performance of core-shell heterojunctions, which could find plausible applications in photodetectors and optoelectronic devices.

Metalens have become one of the most promising metasurfaces for applications in recent years because of their thinness and compactness. Similar to other diffractive elements, the dispersion of metalens is difficult to modulate in the same way as conventional refractive elements. Here, we present a method for designing the polarization-insensitive metalens with linear dispersion via improved particle swarm algorithm (PSO). The metalens operates in the wavelength range of 1.1 ~ 1.3 μm with NA values of 0.36 ~ 0.41. With centrosymmetric nanopillars, the metalens was constructed to be polarization insensitive. By optimizing the reference phase at the center of the metalens using the improved PSO, we are able to obtain a relatively low wave aberration. The optimization convergence rate can be further enhanced with this method compared to the traditional PSO algorithm. FDTD simulation was conducted to abtain the farfield focusing performance of the designed metalens. The dispersion linearity of the metalens is about 11.5% according to the analysis. The dispersion engineering approach proposed in this paper is expected to be applied to micro-spectrometers and other similar devices in the future through further optimization.

Guided-mode resonance (GMR) filters have attracted lots of attention due to their potential applications in filters, semiconductor lasers, modulators and bio-sensors. GMR filters are composed of few dielectric layers and gratings. Compared to the traditional multilayer filters, they are easily fabricated and extremely suitable for the free-space filter as well as the application for the coupling of light from free space to waveguide mode. However, the deviation between the refractive indices of the guiding waveguide and grating is very small because the refractive indices of the polymers are in the range of 1.40 to 1.69, which lagged the design of the polymer GMR filter with a high performance. Here, we proposed novel methods to design polymer GMR reflection filters with single-layer channel for microfluidic application. The side-bands (side-lobe) of the filter are minimized. We also demonstrate the spectrum responses of a tunable microfluidic optical filter with different fluids introduced into the micro-channels based on multilayer polymers. These methods would pave a road to the tunable microfluidic GMR filters.

The diffraction characteristics of amplitude and phase-type soft-edge apertures with super-Gaussian transmittance at the gap of mosaic grating are investigated in this article. A well-designed soft-edge apertures can effectively suppress the Fresnel straight-edge diffraction intensity distribution at a certain transmission distance and consequently homogenize the overall light intensity on the image plane. We use the PV value, which is the difference between the maximum intensity of Fresnel diffraction and the initial incident intensity, as the evaluation index of diffraction intensity homogenization. Compared with use of the hard-edge aperture, the PV value reduces from 0.6 to 0.009 and 0.051 at the distance of 0.5m and 1m respectively with use of the super-Gaussian amplitude type soft-edge apertures designed by us. While using the super-Gaussian phase type soft-edge apertures designed by us, the PV value reduces from 0.6 to 0.053 and 0.06 at the distance of 0.5m and 1m respectively.

Grating absorption is a phenomenon influenced by various factors such as material properties, grating structure, and characteristics of the incident light. Under intense laser irradiation, the absorbed energy of the laser is converted into thermal energy, resulting in an elevated temperature of both the grating and substrate. This temperature rise significantly compromises the optical performance of the grating, thereby imposing constraints on the advancement of high-power laser systems. The numerical simulations were performed using the finite element method to investigate the effects of different absorptivity of grating, spot sizes, substrate materials (Fused silica, BK7 and Sapphire), and convective coefficients of air on the temperature distribution at various locations on the substrate under high-power laser irradiation (30kW/cm²). Comparative analysis reveals that selecting sapphire as the substrate material under high-power laser irradiation results in better heat dissipation.

The resonance scattering caused by the interaction between a dielectric cylinder rotating at a steady angular velocity and a plane wave are studied using the method of separation of variables and the multipole expansion method. In addition, the effect of resonance on curved photonic nanojets (PNJ) is also analyzed. During the study, the critical value of resonance scattering is found by changing the dimensionless and dimensional parameters of the medium cylinder. It is found that the rotation of particles can create and destroy resonance phenomena. The resonance scattering of rotating dielectric cylinders produced by plane waves provides a new direction for the study of PNJ and whispering gallery mode (WGM), as well as the design and application of ultra-sensitive sensors and resonators

Based on the optical Magnus effect, the theoretical framework that scattering generated by a plane wave illuminating a spinning dielectric sphere is proposed using the “instantaneous rest-frame” hypothesis and Minkowski's theory. The analytic expressions of electromagnetic fields are derived for a dielectric sphere rotating around the z-axis exerted by a plane wave illuminating in an arbitrary direction using the method of separation of variables. Both the photonic hook (PH) and the resonance scattering generated by the spinning dielectric sphere are concerned and investigated. The impact of resonance scattering generated by the rotation on the PH is also discussed. The influence of the non-reciprocal rotating dimensionless parameter which determines the existence of PH and resonance to the scattering is emphasized. All the findings in this manuscript have extensive application prospects in particle manipulation, designing of the resonator, and mesotronics.

This paper studies the photonic hooks (PH) generated by the interaction of a dielectric sphere rotating at a certain angular velocity with a plane wave. Based on the instantaneous static frame theory and the partial-wave series expansion method in spherical coordinates, with the help of the separated variable method, we obtain the analytical solutions for the internal and external electric fields of a homogeneous isotropic dielectric sphere rotating around the z-axis irradiated by a plane wave of arbitrary direction. This article focuses on the effect of size parameters (ka), relative refractive index (m1), and rotational dimensionless parameters 𝛾 on PH. The PH produced by this non-reciprocal system can be used not only for trapping off-axis particles, but also has promising applications in low-loss waveguiding, subdiffraction-resolution nanopatterning, and nanolithography.

Beam-steering devices play a vital role in the realm of optical wireless communication (OWC). However, conventional beam-steering technologies based on spatial light modulators, digital micro-mirror devices, gratings, and waveguides have limited performance with tradeoffs between multi-functionalities, high modulation speed, and compactness, which significantly curtail the potential applications of OWC. Herein, a translation-controlled beam-steering metasurface consisting of two metalens arrays is designed, which can achieve high modulation speed, versatile functionalities, and ultra-compactness. In our simulation, multiple functionalities, such as single-angular-mode switching and switching between single-angular-mode and dual-angular-mode have been realized by shifting one of the metalens arrays. Moreover, the dimension of the meta-device is only 200 μm × 200 μm. Our preliminary experimental results show that the switching speed can reach up to 6 KHz. The proposed metasurface circumvents the previous issues, providing a new design paradigm for high-performance OWC.

We report a maskless reactive ion etching (RIE) method that employs O2, CHF3 and SF6&O2 gas plasma sequentially to generate nano-cones structures on silicon substrates with good uniformity. In this method, nano-cones are made under carefully-controlled conditions that restrict their width and height to 60 nm and 82 nm, respectively. According to the formation trend of nano-cones under different plasma conditions, the contributing mechanism is discussed. With the multiple effects of etching time, chamber pressure and self-bias voltage, the height, angle and density of nano-cones will be varied within a certain range. Given these variations, a nano-cone structure with good uniformity was generated using the following parameters: etching time of 300 s, chamber pressure of 40 mtorr, self-bias voltage of 75 W, and a SF6&O2 flow ratio of 75 sccm: 75 sccm. The experiment in this report demonstrates a promising way to fabricate silicon-based nano-cone structures for photonic and optoelectronic applications, with advantages of the controllability and compatibility of its dry-etching process.