Underwater communication plays a vital role in enabling data transfer between the sea surface and submerged autonomous vehicles, particularly for applications such as ocean monitoring and sea exploration. Compared to conventional acoustic and dominated free space wireless communication, like radio frequency, underwater optical wireless communication (UOWC) offers significantly higher data rates and lower latency. In this paper, we demonstrate the transmission of image data using a light-based optical wireless link from the sea surface to an autonomous underwater vehicle (AUV). The performance of the underwater communication link are evaluated in terms of bit error rate (BER) in various water types, including fresh water, sea water, coastal water, and harbor water. This analysis is essential for understanding the feasibility and reliability of image transfer in diverse underwater environments and supports the design of robust UOWC systems for real-world marine applications.

The rapid development of optical communication systems necessitates the advancement of efficient and versatile all-optical switches. In this study, we propose an indium tin oxide (ITO)-based all-optical switch that harnesses the unique properties of this transparent conducting oxide material. The working principle of the proposed switch relies on the optical Kerr effect, where the refractive index of ITO changes by the influence of incident light. By exploiting the non-linear response of ITO to intense light pulses, we demonstrate its feasibility as a primary component in all-optical switching applications. With ITOs electric tunable ENZ effect, our proposed switch achieves an extinction ratio (ER) of 9.2 dB, insertion loss (IL) of 4.3 dB, and figure of merit (FoM) of 2.14. Our findings reveal that the ITO-based switch exhibits ultrafast response times and low energy consumption, making it suitable for high-speed optical networks.

A novel refractive index (RI) plasmonic biosensor with high sensitivity for human blood group detection is proposed and numerically investigated in the visible and near-infrared (NIR) regime. The proposed structure is based on a metal-insulator-metal (MIM) waveguide with an array of elliptical nanoholes. These nanoholes are used as the sensing surface and support important optical properties, such as extraordinary optical transmission (EOT) and nanoscale confinement of light. We have simulated and optimized the biosensor using RF module of COMSOL Multiphysics software, predicting the sensitivity values of three blood groups (A, O, and B) as 64.26, 101.16, and 82.1 nm/RIU, respectively. High sensitivity, precision, and portability make the reported sensor highly valuable for point-of-care applications, emergency situations, and resource-limited settings. By reducing the time for blood typing procedures and small sample volume requirements, MIM biosensor has the potential to enhance patient care and streamline medical processes.

In this article, a novel hybrid plasmonic waveguide (HPWG)-based all-optical switch (AOS) using zinc-doped cadmium oxide (ZnCdO) is reported and numerically investigated with the finite-element method. This oxide layer, which is a well-known transparent conductive oxide (TCO), can be switched from a dielectric to a metallic phase by electrical tuning the refractive index. The mobility of free-carrier concentration is highly magnified with a nonlinear optical effect induced by the epsilon-near-zero material near the telecommunication wavelength. We have simulated the plasmonic switch using the COMSOL Multiphysics simulator, predicting 13.75 dB extinction ratio (ER), 0.5 dB insertion loss (IL), and 27.5 figure-of-merit (FoM) at 1.55 mu text{m} wavelength. We also performed the reliability study by varying parameters, such as the width and height of the waveguide, which affect the performance of the on-chip switch design. In addition, the proposed AOS can be easily integrated with future silicon photonic circuits for ultrafast switching applications.

A nanoscale 3D hybrid plasmonic waveguide (HPWG) refractive index-cum-temperature sensor has been proposed and simulated in this work. The aqueous analyte (benzene C6H6) sensing is possible over the wavelength range from 1.18∼μ m to 2.2∼μ m. A well-known refractive index (RI) sensing method (or wavelength interrogation) is considered for the proposed Si-TiO2-SiO2-Au nanostructure. The sensor design includes, titanium dioxide (TiO2) layer deposited over the silicon dioxide to enhance the overall sensitivity of the HPWG sensor. The finite element method (FEM) based 3D-numerical simulations are performed for an IR band signal, predicting 1022.75 nm/RIU device sensitivity and 2.95 nm/°C temperature sensitivity. The proposed sensor is suitable for next-generation on-chip biochemical sensing applications with nanoscale dimensions, low cost, and high sensitivity.

A complementary metal oxide semiconductor (CMOS) compatible photonic-plasmonic waveguide with nanoscale dimensions and better optical confinement has been proposed for the infrared (IR)–band applications. The design is based on the multi-layer hybrid plasmonic waveguide (Si–SiO2–Au) structure. The 3D-finite element method (FEM)–based numerical simulations of single slot hybrid plasmonic waveguide (HPWG) confirms 2.5 dB/cm propagation loss and 15 μm−2 confined intensity. Moreover, its application as dual-slot nanograting is studied with higher propagation length and ultra–low–dispersion near the 1550–nm wavelength. The proposed low-dispersion nanoscale grating design is suitable for future lab–on–chip nanophotonic integrated circuits.

ACMOS compatible three-port all-optical silicon switch working in 1.473 to 1.502 μm (extinction ratio (ER) = 5.5 dB, λC = 1.488 μm) and 1.512 to 1.5306 μm (ER = 3.079 dB, λC = 1.52 μm) bands is demonstrated in this work through numerical simulations. However, in spite of the all optical control, having null refractive index contrast between the transmitting and control waveguides of the switch causes the switching merit to deteriorate because of light leaking from the transmitting waveguide. Later, by employing Franz Keldysh effect-induced absorption coefficient tuning of Si1-x Gex (x = 0.85) to replace the silicon control port of the switch, 2.95-dB leakage reduction in the ON state is achieved, which is assessed in detail. Also, our numerical simulations confirmed the bandwidth of 38 GHz, which suggested a multilayer plasmonic waveguide structure.