Biosensors have globally been considered as biomedical diagnostic tools required in abundant areas including the development of diseases, detection of viruses, diagnosing ecological pollution, food monitoring, and a wide range of other diagnostic and therapeutic biomedical research. Recently, the broadly emerging and promising technique of plasmonic resonance has proven to provide label-free and highly sensitive real-time analysis when used in biosensing applications. In this review, a thorough discussion regarding the most recent techniques used in the design, fabrication, and characterization of plasmonic biosensors is conducted in addition to a comparison between those techniques with regard to their advantages and possible drawbacks when applied in different fields.

In this work, we are proposing a silicon (Si) based concentric tube broadband absorber. The proposed broadband absorber is composed of consecutive concentric tubes of intrinsic Si and doped-Si (D-Si) layers. The structure exhibits a broadband performance within a wide range of mid-IR wavelength spectrum extending from 3 to 7 µm with an absorption peak that varies between 0.88 and 0.97 in the case of S-polarized incident light. We report that light coupling to the proposed concentric tube metamaterial absorber structure over a broad wavelength range is a result of exhibiting multiple resonance mechanisms at different wavelengths. We further show that bulk plasmon polaritons are excited within the layers leading to this noticeable absorption. We demonstrate CMOS compatible metamaterial absorber that is less dependent on polarization and angle. Furthermore, this proposed design reveals new avenues to realize silicon-based broadband absorption for mid-IR photo detection and mid-IR thermal harvesting applications.

Over a century ago, the study of blackbody radiation led to the development of quantum mechanics. A blackbody is a perfect absorber, absorbing all the electromagnetic light that illuminates it. There is no radiation passing through it, and none is reflected. Now, "bodies" with high absorption qualities are very important in many disciplines of research and technology. Perfect absorbers, for example, can be utilized as photodetectors, thermal pictures, microbolometers, an d thermal photovoltaic solar energy conversion. The Mid-infrared (MIR) wavelength spectrum has numerous advantages in a variety of applications. One of these uses is chemical and biological detection. In this paper, a metasurface mid -IR absorber based on the fractal technology of a doped silicon geometry resonator to realize wideband cross-fractal formation is introduced. The structure exhibits a broadband absorption within a wide range of IR wavelength spectrum extending from 3 to 9 μm. The structure was based on the Sierpinski carpet where different building blocks were simulated to reach the highest absorption. It is shown that light coupling over a broad wavelength range to the proposed fractal metamaterial absorber structure is due to multiple resonance mechanisms at different wavelengths. The propo sed structure is CMOS-compatible. Moreover, this proposed design opens the door to the development of new silicon -based absorbers for different applications such as energy harvesting and photodetection.

A new design of a multimode interference (MMI) phased array structure is proposed. This design is based on replacing the arrayed delay arms between the first MMI power splitter and the second MMI combiner by periodic segmented waveguides. This allows a straight structure without curved waveguides and thus reduces greatly the size of the structure. A design example of an 8 channel multiplexer is presented showing a size reduction by a factor of 23 when compared with conventional design, while keeping nearly the same performance.

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