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 propose an optimized design for on-chip gas sensor using metal-insulator (MI) plasmonic waveguide in the mid infrared range and utilizing a Mach-Zehnder Inetrferometer (MZI). The MI waveguide utilizes a high index dielectric layer on top of the metal to enhance the sensitivity of the sensor. The thickness and the refractive index of this layer are optimized to achieve high sensitivity. Using this layer, a design that exhibits high performance for both wavelength and intensity interrogation schemes is achieved. In addition, another one that furtherly enhances the sensor performance for intensity interrogation is also proposed. This design also minimizes the sensor sensitivity to wavelength variations. Intensity interrogation scheme has the advantage of eliminating the size and cost needed by wide wavelength band measurements including either spectrometer or tunable laser in wavelength interrogation. The first design sensitivity has reached 10000 nm/RIU with wavelength interrogation figure of merit (FOM_λ) of 133RIU⁻¹ and intensity interrogation FOM_I of 239RIU⁻¹. While the second one exhibit FOM_I of 363RIU⁻¹, both with length of 250 µm around 4.6 µm wavelength. Finally, these structures are cheap, compact, and easy to fabricate.

Electrical interconnects are becoming a bottleneck in the way towards meeting future performance requirements of integrated circuits. Moore’s law, which observes the doubling of the number of transistors in integrated circuits every couple of years, can no longer be maintained due to reaching a physical barrier for scaling down the transistor’s size lower than 5 nm. Heading towards multi-core and many-core chips, to mitigate such a barrier and maintain Moore’s law in the future, is the solution being pursued today. However, such distributed nature requires a large interconnect network that is found to consume more than 80% of the microprocessor power. Optical interconnects represent one of the viable future alternatives that can resolve many of the challenges faced by electrical interconnects. However, reaching a maturity level in optical interconnects that would allow for the transition from electrical to optical interconnects for intra-chip and inter-chip communication is still facing several challenges. A review study is required to compare the recent developments in the optical interconnects with the performance requirements needed to reach the required maturity level for the transition to happen. This review paper dissects the optical interconnect system into its components and explains the foundational concepts behind the various passive and active components along with the performance metrics. The performance of different types of on-chip lasers, grating and edge couplers, modulators, and photodetectors are compared. The potential of a slot waveguide is investigated as a new foundation since it allows for guiding and confining light into low index regions of a few tens of nanometers in cross-section. Additionally, it can be tuned to optimize transmissions over 90° bends. Hence, high-density opto-electronic integrated circuits with optical interconnects reaching the dimensions of their electrical counterparts are becoming a possibility. The latest complete optical interconnect systems realized so far are reviewed as well.

Over the past decade, deep learning (DL) has been applied in a large number of optical sensors applications. DL algorithms can improve the accuracy and reduce the noise level in optical sensors. Optical sensors are considered as a promising technology for modern intelligent sensing platforms. These sensors are widely used in process monitoring, quality prediction, pollution, defence, security, and many other applications. However, they suffer major challenges such as the large generated datasets and low processing speeds for these data, including the high cost of these sensors. These challenges can be mitigated by integrating DL systems with optical sensor technologies. This paper presents recent studies integrating DL algorithms with optical sensor applications. This paper also highlights several directions for DL algorithms that promise a considerable impact on use for optical sensor applications. Moreover, this study provides new directions for the future development of related research.

ZnS quantum dots (QDs) were fabricated using the co-precipitation technique with no capping agent. The effects of different annealing temperatures (non-annealed, 240 °C and 340 °C for 2 h) on the structural and optical characteristics of ZnS QDs are reported. The samples were examined by XRD, TEM, PL, FTIR, and UV–Vis. An increase in annealing temperature led to an increase in the dot size and a lowering of the energy band gap (E_G). The average crystallite size, D of ZnS was between 4.4 and 5.6 nm. The ZnS QDs showed a band gap of 3.75, 3.74 and 3.72 eV for non-annealed, 240 °C, and 340 °C annealed samples. The reflection spectra increased in the visible light and decreased in UV region with an increase in annealing temperature. This work showed that the band gap and size of ZnS QDs could be tuned by varying the annealing temperature.

In this paper, novel ultra compact and ultra wide band couplers between silicon and plasmonic slot waveguides are analyzed, characterized, and fabricated. This novel coupling scheme is fabricated using silicon on insulator platform. An orthogonal junction configuration is designed to provide non-resonate wideband coupling from a 400 nm silicon waveguide to 50-nm wide air-filled plasmonic slot. The 1 μm wide full-width half-max coupling spectrum can theoretically reach high peak of 70% coupling to the plasmonic slot centered around the 1550 nm wavelength. This center wavelength can be controlled by varying the silicon waveguide width. Theoretical analysis is in good agreement with FDTD simulated results, and experimental results. The fabrication procedure is also presented and discussed.