Du Chunlei

The theoretic analysis of maskless surface plasmon resonant interference lithography by prism coupling

The use of an attenuated total reflect ion-coup ling mode of prism coated with metal film to excite the interference of the surface plasmon polaritons (SPPs) was proposed for periodic patterning with a resolution of subwavelength scale. High intensity of electric field can be obtained because of the coupling between SPPs and evanescence under a resonance condition, which can reduce exposure time and improve contrast. In this paper, several critical parameters for maskless surface plasmon resonant lithography are described, and the preliminary simulation based on a finite difference time-domain technique agrees well with the theoretical analysis, which demonstrates this scheme and provides the theoretical basis for further experiments.

Discrete Dipole Approximation Aided Design Method for Nanostructure Arrays

A discrete dipole approximation (DDA) aided design method is proposed to determine the parameters of nanostructure arrays. The relationship between the thickness, period and extinction efficiency of nanostructure arrays for the given shape can be calculated using the DDA. Based on the calculated curves, the main parameters of the nanostructure arrays such as thickness and period can be determined. Using this aided method, a rhombic sliver nanostructure array is designed with the determinant parameters of thickness (40 nm) and period (440 nm). We further fabricate the rhombic sliver nanostructure arrays and testify the character of the extinction spectra. The obtained extinction spectra is within the visible range and the full width at half maximum is 99 nm, as is expected.

Near-Field Optical Transfer Function for Far-Field Super-Resolution Imaging

The far-field superlens based on surface plasmon polaritons (SPP) has shown great application potential, but it is difficult and time-consuming to reconstruct the far-field image. We derive a near-field optical transfer function (NOTF) of a silver slab and analyse its validity so that accurate information of nano-scale object in the near-field can be computed rapidly. The NOTF is helpful not only for analysing the super-resolution imaging process in far-field, but also for providing a track to describe the transmission of optical information from near-field to far-field by using the optical transfer functions theory only.

Propagation properties of Gaussian-Shaped and double-side unsymmetrical metallic nano-corrugations

A Gaussian-shaped and double-side unsymmetrical groove structure is presented. Rigorous calculation of the optical properties of the structure is performed on the basis of a multiple multipole program. We analyse the effect of the grating period, the groove width and the film thickness on transmission and reflectance. Simulation results demonstrate that surface-plasmon-polariton resonance positions depend strongly on the structure period and can be changed slightly by the variation of incomplete perforation thickness, while the resonance peak values can be controlled by tuning the groove width. Our results not only give an insight into the physical mechanisms of the double-side unsymmetrical gratings, but also open a way to design novel nano-photonic devices.

Multiple Wavelength-Channels in SPP Waveguides for Optical Communication

Surface plasmon polaritons (SPPs) can be excited, meanwhile some peculiar optical phenomena will appear when light irradiates metal structures under some conditions. Based on photonic band gap theory, in this Letter we present a kind of SPP waveguide with multiple wavelength-channels. By using the Bragg efiect and introducing some geometric defect layers into a quasi-periodic metal heterowaveguide, the multiple SPP forbidden bands (SPFBs) in a given waveband can be generated, and the multiple SPP pass bands (SPPBs) with narrow bandwidth in each SPFB can be realized. The SPP propagation in metal heterowaveguide is calculated by FDTD and transfer matrix methods. By selecting appropriate thickness, position and the number of defect layers, two SPPBs can be achieved in the SPFBs around 1.31 and 1.55„m simultaneously.

Formation for Bass-Relief Microprofiles Based on an Analytic Formulation

A method of fast design and fabrication for bass-relief micro-profiles is developed by using an analytic formulation to determine the exposure distribution. Based on an equivalent exposure threshold model, the formulation is simplified for the case of bass-relief profile corresponding to the smaller exposure dose. The mask function for a microlens array is designed without iteration involved by the analytic formulation. The experiment is performed to validate the method, and the fabrication result is obtained with the profile error less than 30 nm (rms).

Swift perspective shape matching algorithm based on Phong’s model for FPC stiffener bonding systems

Purpose – This paper aims to solve the issue of target positioning in auto stiffener bonder (ASB) systems for flexible printed circuits. Design/methodology/approach – The proposed approach uses Phong’s bidirectional reflectance distribution function (BRDF) model to simulate the reflection of light off a target in ASB systems to predict the current pose of the target based on image brightness, update the template, decrease the initial errors in the template and narrow down the search range. Findings – The experimental results indicate that the proposed approach can predict the inclination angle of the target with precision, presenting angle prediction errors of less than three degrees. Furthermore, with larger inclined angles, the overall matching errors were less than 1.5 pixels. Comparisons with the unmodified matching algorithm revealed that the proposed approach resulted in 65 per cent less calculation time for the algorithm and 14 per cent higher overall work efficiency in the ASB system. Originality/...

Spatial Light Modulator Based on Surface Plasmon Polaritons for Chromatic Display

A spatial light modulator (SLM) based on surface plasmon polaritons (SPPs) that can generate chromatic pattern is demonstrated. The device is composed of a waveguide with a thin silver film and an active material The simulated results show that the SLM can modulate the intensity of three different wavelengths at the same time and combine a colour picture in the image surface. The SLM also owns the characteristics of high sensitivity, high contrast, fast time response etc. This means that the SLM is promising in the chromatic display.