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Chirality plays a key role in biochemical reaction and the self-assembled mechanism of life. The detection of chiral molecules is one crucial issue in biology, clinic, pharmacy and food security fields, which usually refers to the detectable chiroptical effect, i.e. circular dichroism (CD) and optical rotatory dispersion (ORD) Gansel et al. (2009), Quake and Scherer (2000), Pendry (2004), Zhang et al. (2009), Kastel et al. (2007) 1-5. However, the chiroptical effect from chiral molecules in nature (such as proteins and DNAs) is usually very small and located in ultraviolet spectral region. This limits the detection sensitivity of chiral molecules and their ability to control electromagnetic wave. In this paper, we report a scalable fabrication of a new kind of chiral molecule@nanoparticle complex materials, which are composed of an achiral nano-cup array and a pair of chiral molecules (l-/d-cysteine). The nano-cup array with localized surface plasmonic response peak of 630nm is obtained with the micro-sphere assembly technique, which is a kind of scalable, low-cost and material-independent fabrication method. After coating a layer of chiral molecules on the surface of the nano-cup array, a clear induced-CD peak in visible region is demonstrated from the l/d-cysteine@nano-cups complex materials, the intensity of which can be much greater than the existing results 9-16. Full-wave electromagnetic simulation method has been performed to get insight into the mechanism of the induced chiroptical effect. The simulation results indicate that this giant induced CD signal should be attributed to the electromagnetic interaction between chiral molecules and plasmonic nanostructures, especially for the wave at the plasmonic resonance peak. These results indicate the potential application prospect of these newly-fabricated complex chiral materials. Display Omitted A new kind of molecule@nanoparticle complex materials are fabricated.The complex materials have greatly enhanced induced CD signal in visible region.The physical mechanism of induced CD signal is studied.

Based on the models of thin-layer resist exposure and developing,the SPPs resist exposure model is established.Two kinds of resist of AZ1500 and AR3170 are chosen to simulate the process of exposure and developing,and the final profile of SPPs lithography is obtained.Some craft optimization conditions are also conclucled.The research results are for experiment and future work of SPPs lithography.

This paper describes a multi-reflected mode based on a narrow waveguide to enlarge the interferential area of surface plasmon polaritons (SPPs). A reasonable thickness of metal film is coated under the waveguide, the incident angle and the waveguide thickness are optimized in order to effectively increase interferential area. This is a key point for research into the Goos–Hanchen shift to optimize the waveguide thickness. Finally, the SPP interferential field is simulated with the finite-difference time-domain (FDTD) technique to prove the optimized results, and indicates that not only is the interferential area enlarged, but the high contrast is also maintained. Furthermore, the mode can fabricate some specific interferential patterns by adding some modulating techniques to the waveguide. So the mode has potential application in the fabrication of sub-wavelength patterns.

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.

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.

The thick film photoresist lithography is a much more complicated process compared to the thin film photoresist lithography. In this paper, we have developed a new model for lithography of thick film photoresist by using the angular spectrum theory. The thick film photoresist is divided into many homogeneous layers, and the diffractive optical imaging distribution in photoresist is regarded as superposition of different spectrum plane waves. Propagation of each plane wave is determined by the optical transfer function, and the propagation direction, amplitude and phase are dominated by reflection and transmission between each interface of the sub-layers. The fast Fourier transform (FFT) has been converted into a convolution calculation to keep the computation accurate and reduce computation cost. Numerical calculation results show that optical intensity in cross-sect of thick film resist is strongly affected by reflection, transmission on interface and variation of dielectric permittivity along direction of depth, and therefore these factors should be considered while analyzing diffractive imaging field in thick film photoresist.

The gradient phased interface is characterized by a non-zero phase variation along the interface between two optical media,which could generate a phase shit between the emitted and incident light beams.Unlike common ones,gradient phased interfaces have a great influence on the laws of light propagation,including light reflection and refraction,and some novel phenomena are observed.For a comprehensive understanding the optical characteristics of those gradient surfaces,the universal laws of light propagation at gradient phased interfaces are derived and discussed in detail in this paper.According to Fermat's principle,we use the stationary phase method to successively acquire the two-dimensional (2D) and three-dimensional (3D) generalized laws of reflection and refraction.In the 2D generalized laws,the interfacial phase gradient lies in the plane of incidence,which is coplanar with the incident,refracted and reflected light beams. But in the 3D case,the phase gradient does not lie in the plane of incidence,and the non-planar reflection and refraction phenomena are observed.These generalized reflection and refraction laws indicate that the interface between two media could be an important factor when light traverses it,and gradient phased interfaces provide new degrees of freedom for manipulating the wavefront of light beams.Based on the generalized reflection and refraction laws,we analyze the influence of phase gradient on light propagation,then obtain critical angles of incidence for reflection and refraction (i.e.the critical angles for total internal reflection and total transmission) in 2D and 3D cases,and explain the reasons for some novel phenomena,such as reflection angle unequal to incidence angle,anomalous reflection and refraction, out-of-plane reflection and refraction,etc.These analysis results show that generalized laws of reflection and refraction have important value in optical design.In addition,we propose an optical design idea based on generalized laws of reflection and refraction,in which gradient phased interfaces are used as core components of optical elements to perform optical transform.And then a flat lens and flat axicon are taken for example to illustrate this idea,the design process of the two flat optical elements are shown in detail.Moreover,we experimentally simulate the gradient surfaces of the two elements by spatial light modulator,and experimental results agree well with theoretical values.It proves that this design idea is practicable.Our research is useful to understand comprehensively the generalized reflection and refraction laws,and extend the applications of generalized laws to flat optics,freeform optics and the accurate control of complex wavefront.

We present a narrow band forward scattering optical antenna which is based on the excitation of distinctive whispering gallery modes (WGMs). The antenna is composed of three coaxial cylinder layers: a dielectric layer is sandwiched between a metallic core and cladding. Owing to the destructive interference between the scattering of the outer metallic cladding and the WGM in the backward direction, the power flow in the forward direction is increased. Simulation and analysis show that in proper geometry conditions, the cavity can be tuned into a superscattering state. At this state, both the zeroth and the first order of WGM are excited and contribute to the total scattering. It is shown that the power ratio (power towards backward divided by power towards forward) can be enhanced to about 27 times larger than that for a non-resonant position by the superscattering. Owing to the confinement of the cladding to WGMs, the wavelength range of effective forward scattering is considerably narrow (about 15 nm).

The methods for improving the focusing properties of subwavelength metallic lens by optimizing the groove width and depth of the structure simultaneously are presented. We investigate how the variations of the width and depth of the groove affect the half width at half maximum of the focus, intensity, normal focusing efficiency of the focal spot and the focal length, based on the finite-difference and time-domain method. The optimum design methods of metal lens are put forth through discussing the focusing regularity and physical mechanism, which can provide a theoretical basis for realizing the nano-focusing and flexible manipulation of light wave based on metallic lens.

Interference nanolithography techniques based on long-range surface plasmon polaritons (LR-SPP) are hardly ever achieved by experiments at present. One key reason is that suitable liquid materials are difficult to find as the match layer connects the metal film and the resist. We redesign a Kretschmann−Raether structure for interference lithography. A polymer layer is coated under the metal film, and an air layer is placed between the polymer layer and the resist layer. This design not only avoids the above-mentioned question of the match layer, but also can form a soft contact between the polymer layer and the resist layer and can protect the exposure pattern. Simulation results confirm that a device with an appropriately thick polymer layer can form high intensity and contrast interference fringes with a critical dimension of about λ/7 in the resist. In addition, the fabrication of the device is very easy.

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.