A single-step, low-cost fabrication method to generate resonant nano-grating patterns on poly-methyl-methacrylate (PMMA; plexiglas) substrates using thermal nano-imprint lithography is reported. A guided-mode resonant structure is obtained by subsequent deposition of thin films of transparent conductive oxide and amorphous silicon on the imprinted area. Referenced to equivalent planar structures, around 25% and 45% integrated optical absorbance enhancement is observed over the 450-nm to 900-nm wavelength range in one- and two-dimensional patterned samples, respectively. The fabricated elements provided have 300-nm periods. Thermally imprinted thermoplastic substrates hold potential for low-cost fabrication of nano-patterned thin-film solar cells for efficient light management.

Resonant leaky modes can be induced on dielectric, semiconductor, and metallic periodic layers patterned in one or two dimensions. In this paper, we summarize their physical basis and present their applicability in photonic devices and systems. The fundamental amplitude and phase response of this device class is presented by computed examples for TE and TM polarizations for lightly and heavily spatially modulated gratings. A summary of potential applications is provided followed by discussion of representative examples. In particular, we present a resonant polarizer enabled by a single periodic silicon layer operating across 200-nm bandwidth at normal incidence. Guided-mode resonance (GMR) biosensor technology is presented in which the dual-polarization capability of the fundamental resonance effect is applied to determine two unknowns in a biodetection experiment. In principle, using polarization and modal diversity, simultaneously collected data sets can be used to determine several relevant parameters in each channel of the sensor system; these results exemplify this unique capability of GMR sensor technology. Applying the GMR phase, we show an example of a half-wave retarder design operating across a 50-nm bandwidth at λ~1550 nm. Experimental results using a metal/dielectric design show that surface-plasmon resonance and leaky-mode resonance can coexist in the same device; the experimental results fit well with theoretical simulations.

Accurate and fast breath monitoring is of great importance for various healthcare applications, for example, medical diagnoses, studying sleep apnea, and early detection of physiological disorders. Devices meant for such applications tend to be uncomfortable for the subject (patient) and pricey. Therefore, there is a need for a cost-effective, lightweight, small-dimensional, and non-invasive device whose presence does not interfere with the observed signals. This paper reports on the fabrication of a highly sensitive human respiratory sensor based on silicon nanowires (SiNWs) fabricated by a top-down method of metal-assisted chemical-etching (MACE). Besides other important factors, reducing the final cost of the sensor is of paramount importance. One of the factors that increases the final price of the sensors is using gold (Au) electrodes. Herein, we investigate the sensor’s response using aluminum (Al) electrodes as a cost-effective alternative, considering the fact that the electrode’s work function is crucial in electronic device design, impacting device electronic properties and electron transport efficiency at the electrode–semiconductor interface. Therefore a comparison is made between SiNWs breath sensors made from both p-type and n-type silicon to investigate the effect of the dopant and electrode type on the SiNWs respiratory sensing functionality. A distinct directional variation was observed in the sample’s response with Au and Al electrodes. Finally, performing a qualitative study revealed that the electrical resistance across the SiNWs renders greater sensitivity to breath than to dry air pressure. No definitive research demonstrating the mechanism behind these effects exists, thus prompting our study to investigate the underlying process.