The research on optical packet switching has witnessed considerable progress in the 1990s. In this article we examine the future potential of OPS in the core network by discussing this switching approach and the current status of a number of its enabling technologies. Many of these technologies are still in the stage of research and experimentation. We see that optical packet switching may be deployed in the long-term future subject to satisfaction of three main conditions/developments. First, additional technological developments have to take place to overcome remaining implementation challenges while making OPS cost-effective to deploy. Second, a rational migration scenario of the network toward gradual deployment of packet-based optical switching approaches should exist. Finally, carriers have to become more interested in packetbased optical switching solutions.

The sudden rise of the worldwide severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in early 2020 has called into drastic action measures to perform instant detection and reduce the rate of spread. Common clinical and nonclinical diagnostic testing methods have been partially effective in satisfying the increasing demand for fast detection point-of-care (POC) methods to slow down further spread. However, accurate point-of-risk diagnosis of this emerging viral infection is paramount as the need for simultaneous standard operating procedures and symptom management of SARS-CoV-2 will be the norm for years to come. A sensitive, cost-effective biosensor with mass production capability is crucial until a universal vaccination becomes available. Optical biosensors can provide a noninvasive, extremely sensitive rapid detection platform with sensitivity down to ∼67 fg/ml (1 fM) concentration in a few minutes. These biosensors can be manufactured on a mass scale (millions) to detect the COVID-19 viral load in nasal, saliva, urine, and serological samples, even if the infected person is asymptotic. Methods investigated here are the most advanced available platforms for biosensing optical devices that have resulted from the integration of state-of-the-art designs and materials. These approaches include, but are not limited to, integrated optical devices, plasmonic resonance, and emerging nanomaterial biosensors. The lab-on-chip platforms examined here are suitable not only for SARS-CoV-2 spike protein detection but also for other contagious virions such as influenza and Middle East respiratory syndrome (MERS).

An in-line submillimeter hole fabricated by microdrilling plastic optical fiber (POF) directly has been proposed as a compact refractive index sensor. Since the hole behaves as a concave lens if it is filled with a liquid having lower refractive index than that of the fiber core, transmittance increases in proportion to the refractive index. Analysis of the sensor transmittance has been performed using a simple ray optics model. Through immersing a 1.5-mm POF with a 0.35-mm-radius hole into various liquids, transmittance of the sensor has been measured at 670 nm. It has been shown that the experimental and analytical results are in excellent agreement.Index Terms-Fiber optic sensors, plastic optical fiber, refractive index sensors, microstructure fabrication.

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Compact, lightweight, high-power beam-steering devices operating in the mid-infrared atmospheric window λ = 3 − 5 µ m are attractive for aerial-based applications such as long-range lidar and countermeasures. In the near-infrared spectral region, optical phased arrays (OPAs) have emerged as the dominant nonmechanical on-chip beam-steering technology, with a preponderance in silicon-based platforms. Extensions to the mid-infrared spectral region are scarce. Further, considering that the requirements for high performance in this region will likely demand monolithic integration with quantum cascade lasers, development of the photonic technology on a native III–V platform is advantageous. To this end, at λ = 4.6 µ m , on an InGaAs/InP platform, we experimentally demonstrate the operation of a 32-channel OPA with thermo-optic tuning for azimuthal (lateral) steering. With a waveguide spacing of 2.5 λ , we steer the beam to the maximum uninfringed field of view at ± 11.5 ∘ .

We proposed an optical true time-delay (TTD) feeder for X-band linear phased array antennas (PAAs), which possesses high-speed beam scan capability by selecting different lengths of fiber delay lines with fast 2 2 optical microelectromechanical system switches. For proof of concept, a 3-bit optical TTD has been built for a 10-GHz linear PAA composed of two antenna elements. Experimental results show that the maximum time-delay error is less than 0.2 ps, corresponding to a radiation angle error of less than 0.84 , which is within the equipment resolution. We have also designed a 10-GHz linear PAA composed of eight microstrip patch antenna elements driven by the proposed TTD. The radiation patterns of this PAA have been obtained by simulation.Index Terms-Beam forming networks, optical microelectromechanical system (MEMS), phased array antennas (PAAs), true time-delay (TTD).

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