Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

The present disclosure pertains to metal or dielectric nanostructures of the subwavelength scale within the grating lines of optical diffraction gratings. The nanostructures have surface plasmon resonances or non-plasmon optical resonances. A linear photodetector array is used to capture the resonance spectra from one of the diffraction orders. The combined nanostructure super-grating and photodetector array eliminates the use of external optical spectrometers for measuring surface plasmon or optical resonance frequency shift caused by the presence of chemical and biological agents. The nanostructure super-gratings can be used for building integrated surface enhanced Raman scattering (SERS) spectrometers. The nanostructures within the diffraction grating lines enhance Raman scattering signal light while the diffraction grating pattern of the nanostructures diffracts Raman scattering light to different directions of propagation according to their wavelengths. Therefore, the nanostructure super-gratings allows for the use of a photodetector array to capture the surface enhanced Raman scattering spectra

Wideband Optical Filters with Small Gap Coupled Subwavelength Metal Structures

In this letter, we show that the bandwidth of optical band-stop filters made of subwavelength metal structures can be significantly increased by the strong plasmonic near-field coupling through the corners of the periodic metal squares. The effect of small gap coupling on the spectral bandwidth is investigated by varying the gap size between the metal squares. An equivalent transmission line model is used to fit the transmission and reflection spectra of the metal filters. The transmission line model can characterize well the metal structures with the gap size larger than the near-field decay length. However, it fails to model the transmission and reflection spectra when the gap size reaches the decay range of the near-field in the small gaps

Subwavelength metal grating metamaterial for polarization selective optical antireflection coating

A metamaterial structure consisting of a one-dimensional metal/air-gap subwavelength grating is investigated for optical antireflection coating on germanium substrate in the infrared regime. For incident light polarized perpendicularly to the grating lines, the metamaterial exhibits effective dielectric property and Fabry-Perot like plasmon-coupled optical resonance results in complete elimination of reflection and enhancement of transmission. It is found that the subwavelength grating metamaterial antireflection structure does not require a deep subwavelength grating period, which is advantageous for device fabrication. Maximal transmittance of 93.4% with complete elimination of reflection is seen in the mid-wave infrared range.Comment: 6 pages, 11 figure

Emotion as a Signal of Product Quality: Exploring Its Effects on Purchase Decisions In Online Customer Reviews

Two critical problems of online customer reviews is the caused information asymmetry and information overload. To reveal consumers’ information processing under this circumstance, this paper proposes a model to investigate pleasure versus displeasure embedded in reviews as a potential signal of product quality and the moderating effects of perceived empathy and perceived cognitive effort based on the signaling theory. A laboratory experiment with 120 subjects was used to empirically test the research hypotheses. The results show that pleasure and displeasure embedded in reviews influence perceived product quality, which subsequently affects purchase decisions. Additionally, pleasant online reviews were found to have a greater influence on perceived product quality compared to unpleasant online reviews when the perceived empathy and perceived cognitive effort are higher. The findings demonstrate positive effects of pleasant online customer reviews, and provide important practical implications for both sellers and consumers

How to Respond to Help Requests in Marketing Campaigns on Social Network Sites: A Communication Privacy Management Perspective

SNSs are becoming a preferred venue to conduct marketing campaigns to promote brands, products, and services. Therefore, it is imperative for merchants and SNS providers to substantively understand individual users’ response to help requests in a marketing campaign in SNSs. Drawing on the communication privacy management theory and privacy calculus perspective, this paper examines the main and interaction effects of privacy assurance from a merchant and relationship closeness with a sender on a recipient’s participation behaviors through the recipient’s privacy assessments in terms of privacy concerns and social rewards. A lab- controlled experiment was proposed to test the hypotheses in this short paper. A pilot study of 43 subjects confirmed the validity of experiment setting, and shows preliminary strong evidences to support the proposed hypotheses. Both theoretical and practical implications of the findings are expected

Investigation of Plasmon Resonance Tunneling through Subwavelength Hole Arrays in Highly Doped Conductive ZnO Films

Experimental results pertaining to plasmon resonance tunneling through a highly conductive zinc oxide (ZnO) layer with subwavelength hole-arrays is investigated in the mid-infrared regime. Gallium-doped ZnO layers are pulsed-laser deposited on a silicon wafer. The ZnO has metallic optical properties with a bulk plasma frequency of 214 THz, which is equivalent to a free space wavelength of 1.4 μm. Hole arrays with different periods and hole shapes are fabricated via a standard photolithography process. Resonant mode tunneling characteristics are experimentally studied for different incident angles and compared with surface plasmontheoretical calculations and finite-difference time-domain simulations. Transmission peaks, higher than the baseline predicted by diffraction theory, are observed in each of the samples at wavelengths that correspond to the excitation of surface plasmon modes