We propose a method for creating a three-dimensional (3D) shape-controllable focal spot array by combination of a two-dimensional (2D) pure-phase modulation grating and an additional axial shifting pure-phase modulation composed of four-quadrant phase distribution unit at the back aperture of a high numerical aperture (NA) objective. It is demonstrated that the one-dimensional (1D) grating designed by optimized algorithm of selected number of equally spaced arbitrary phase value in a single period could produce desired number of equally spaced diffraction spot with identical intensity. It is also shown that the 2D pure-phase grating designed with this method could generate 2D diffraction spot array. The number of the spots in the array along each of two dimensions depends solely on the number of divided area with different phase values of the dimension. We also show that, by combining the axial translation phase modulation at the back aperture, we can create 3D focal spot array at the focal volume of the high NA objective. Furthermore, the shape or intensity distribution of each focal spot in the 3D focal array can be manipulated by introducing spatially shifted multi vortex beams as the incident beam. These kinds of 3D shape-controllable focal spot array could be utilized in the fabrication of artificial metamaterials, in parallel optical micromanipulation and multifocal multiphoton microscopic imaging.

A simple and efficient electrochemical assay based on self-assembled monolayers (SAMs) was developed for the highly sensitive determination of arsenic(III) in water samples. The synergy of glutathione (GSH), dithiothreitol (DTT) and N-acetyl-L-cysteine (NAC) mixed SAMs enhanced the detection specificity and sensitivity of As(III) in water samples, resulting from the immobilization of a large number of As(III) moieties on the gold electrode surface via As-O and As-S linkages. After accumulating As(III), anodic stripping voltammetry (ASV) was performed, and linear sweep voltammetry (LSV) was employed for signal recording. Several main voltammetric parameters were optimized as follows: supporting electrolyte, 1 mol L À1 HCl; deposition potential, À0.35 V; deposition time, 150 s. A good linear relationship (R ¼ 0.9980) was attained between the concentration of the As(III) standard and peak current, in the range of 3-100 mg L À1. The limit of detection (LOD) of this sensing system was determined to be 0.5 mg L À1 at a signal-to-noise ratio of 3. A variety of common coexistent ions in water samples were examined, showing no obvious interferences on the As(III) determination. The amenability of this method to the analyses of water samples was also investigated. High recovery of 90.5% with the precision of 5.1% at spiked 10 mg L À1 , and low LOD of 0.3 mg L À1 were obtained in seawater. The synergy effect of GSH, DTT and NAC provided the possibility for the rapid and sensitive LSV determination of As(III) in complicated water samples.

Temperature and wavelength dependence of energy transfer (ET) process between quantized states and surface trap states of CdSe quantum dots was investigated, respectively. The experimental results demonstrate that the photoluminescence (PL) intensity of the quantized states decreases with respect to the trap state emission, especially at lower temperatures. The observed ET process between quantized states and trap states which is influenced by the thermal population behavior. At the same temperature, the silver films can greatly enhance the energy transfer (ET) rate from the quantized states to trap states due to surface plasmonic coupling effect.

We propose a method for producing multifocal spot arrays (MSAs) capable of controlling the position and polarization orientation of each focal spot with radially polarized Bessel-Gaussian beam. Based on a simple analytical equation that can be used to manipulate the position of the focal spot, we design a type of multi-zone plate (MZP) composed of many fan-shaped subareas which accordingly generate lateral position-controllable multifocal spots. By adding a π-phase difference between a division line passing through the center of the back aperture with different orientations to corresponding subareas of the MZP, we realize MSAs in which orientations of the linear polarization in each focal spot can be arbitrarily manipulated. Such position and polarization controllable MSAs may potentially have applications in many fields.

We propose an approach for generating a multifocal spot array (MSA) with a high numerical aperture (NA) objective. The MSA is generated by using a special designed phase-only modulation at the back aperture of an objective. Without using any iteration algorithm, the modulated phase pattern is directly obtained by the simple analytical expressions based on the fractional Talbot effect. It is shown that the number of the spots in the focal region depends solely on the fractional Talbot parameter. By engineering the phase pattern with a large fractional Talbot parameter, a large number of focal spots can be created. Furthermore, the intensity distribution of each focal spot can be manipulated by introducing a composite spatially shifted vortex beam (CSSVB) as the incident field, leading to creation of various kinds of specific shaped spots. Consequently, the MSA composed of multiple individual spots with specific shape is created by focusing the CSSVB combined with the multifocal phase-only modulation. These kinds of MSAs may be found applications in parallel optical micromanipulation, multifocal multiphoton microscopic imaging, and parallel laser printing nanofabrication.