In this paper; the surface plasmon resonance (SPR) sensor with a porous silica film was studied. The effect of the thickness and porosity of the porous silica film on the performance of the sensor was analyzed. The results indicated that the figure of merit (FOM) of an SPR sensor can be enhanced by using a porous silica film with a low-refractive-index. Particularly; the FOM of an SPR sensor with 40 nm thick 90% porosity porous silica film; whose refractive index is 1.04 was improved by 311% when compared with that of a traditional SPR sensor. Furthermore; it was found that the decrease in the refractive index or the increase in the thickness of the low-refractive-index porous silica film can enlarge the FOM enhancement. It is believed that the proposed SPR sensor with a low-refractive-index porous silica film will be helpful for high-performance SPR sensors development.

Abstract-In this work, a far field imaging model based on the array structure of positive-and negative-refractive-index media and modulation subwavelength-gratings is firstly presented and is named as the multilayer far field superlens (MLFSL). This new lens is capable of producing optical images by enhancing evanescent waves to the far field. The principle of MLFSL is discussed in detail, and the necessary and sufficient condition for designing MLFSL is obtained.Simultaneously, off-axis illumination technology is introduced to MLFSL system to further improve super-resolution, and the transfer matrix which contains the incident angle is obtained. The results demonstrate that, compared with other far field superlens, the subwavelength resolution of MLFSL has been enhanced. Such remarkable imaging capability of MLFSL promises new potential for nanoscale imaging and lithography.

We propose and demonstrate a novel trumpet hyperlens, based on coordinate transformation incorporated with a conformal mapping approach, which can support the propagation of waves with high wavevectors and realize deep subwavelength resolution focusing. A resolution of 6 nm, about 1/60 of the 365 nm incident wavelength, is obtained, and the normalized focusing efficiency can be optimized to be 177%. By changing the permittivity of the dielectric in agreement with an effective metamaterial description, this lens is expected to focus light over a broad wavelength range.

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A surface plasmon resonance (SPR) sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO 2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit (FOM) depends on the refractive index of absentee layer. By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO 2 (or AlAs) absentee layer is 1.059% (or 2.587%) higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors.