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.

In this paper, we report the analysis, fabrication, and characterization of metallized slotted micromirrors for optical MEMS applications. A scalar model for the transmittance of the micromirror with a vertical slit using Gaussian beam analysis is developed and a closed-form expression is obtained. Detailed finite difference time domain simulation is carried out for the micromirror transmittance to understand the effect of polarization and bench mark the developed model for slit width-to-wavelength ratios in the range 0 to 8. A MEMS chip is designed comprising fiber grooves and variable slit micromirror controlled by a comb-drive actuator. The chip is fabricated using deep reactive ion etching of silicon-on-insulator substrate with 100-μm device layer height. The motion of the actuator is characterized using an opto-mechanical technique and the transmittance of the micromirror for different incident polarizations is extracted versus the slit width and compared with the theoretical predictions showing good agreement.

In this work, we report the analysis, fabrication, and characterization of an optical cavity built using a Bragg-coated fiber (BCF) mirror and a metal-coated microelectromechanical systems (MEMS) slotted micromirror, where the latter allows transmission output from the cavity. Theoretical modeling, using Fourier optics analysis for the cavity response based on tracing the propagation of light back and forth between the mirrors, is presented. Detailed simulation analysis is carried out for the spectral response of the cavity under different design conditions. MEMS chips of the slotted micromirror are fabricated using deep reactive ion etching of a silicon-on-insulator substrate with different device-etching depths of 150 μm and 80 μm with aluminum and gold metal coating, respectively. The cavity is characterized as an optical filter using a BCF with reflectivity that is larger than 95% in a 300 nm range across the E-band and the L-band. Versatile filter characteristics were obtained for different values of the MEMS micromirror slit width and cavity length. A free spectral range (FSR) of about 33 nm and a quality factor of about 196 were obtained for a 5.5 μm width aluminum slit, while an FSR of about 148 nm and a quality factor of about 148 were obtained for a 1.5 μm width gold slit. The presented structure opens the door for wide spectral response transmission-type MEMS filters.

In this work, we present a modal analysis for a metallic slit, where closed-form expressions for the slotted micromirror electric field coupling coefficient and transmittance are derived for both TE and TM polarizations. This can be handy in the design of optical microelectromechanical systems devices and their applications, where the metallic slit is analyzed by solving the eigenfunction problem. The modes excited inside the metallized slotted micromirrors (slit inner structure) are approximated to be the same modes excited inside a parallel plate waveguide structure for TE and TM excitations. The parallel plate waveguide representing the inner walls of the slotted micromirror is assumed to be infinite in the vertical direction. The transmittance of the micromirror with a vertical slit has been calculated for both TE and TM polarizations based on Gaussian beam excitation. Finite-difference time-domain simulation is carried out for the slotted micromirror transmittance, and the results are compared to the modal analysis predictions. A noticeable conformity has been observed.

Invers design with topology optimization becomes one of the most promising methodologies in optical elements design because of its ability of achieving design targets that's the traditional design can't achieve it. In this paper we present one of these challenge by designing high focusing efficiency metalens with high numerical aperture along broadband of wavelength.