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Characterization of optical isolator4/1/2023 ![]() It provides critical functionalities such as optical isolation and circulation in photonic systems. Isolation of light is fundamental in information processing 1. The occurrence of in-plane light isolation is attributed to the information dissipation due to off-plane and side-way scattering and selective modal conversion in the multiple-channel structure and has no conflict with the reciprocal principle. Both numerical simulations and experimental measurements show that the round-trip transmissivity of in-plane infrared light across a silicon photonic crystal slab heterojunction diode could be two orders of magnitudes smaller than the forward transmissivity at around 1,550 nm with a bandwidth of about 50 nm, indicating good performance of optical isolation. Here we demonstrate optical isolation of infrared light in purely linear and passive silicon photonic structures. Recently there have appeared hot controversies upon whether isolation of light can be realized via linear and passive photonic structures. Posts made by guest authors have been subject to peer review.On-chip optical isolation plays a key role in optical communications and computing based on silicon integrated photonic structures and has attracted great attentions for long years. Views and opinions expressed by a guest author are solely their own, and do not necessarily represent those of ISA. ISA blog posts may be authored by ISA staff and guest authors from the automation community. The material and information contained on this website is for general information purposes only. ISA develops widely used global standards certifies professionals provides education and training publishes books and technical articles hosts conferences and exhibits and provides networking and career development programs for its members and customers around the world. ISA advances technical competence by connecting the automation community to achieve operational excellence and is the trusted provider of standards-based foundational technical resources, driving the advancement of individual careers and the overall profession. The International Society of Automation (ISA) is a non-profit professional association founded in 1945 to create a better world through automation. He earned a master's degree from the Medill School at Northwestern University with a focus on science, engineering and biomedical marketing communications, and a bachelor of science degree from UC San Diego. Prior to his work in marketing and PR, Joel served as an editor for regional newspapers and national magazines throughout the U.S. Joel Don is the community manager for ISA and is an independent content marketing, social media and public relations consultant. (Editor), Maintenance of Instruments and Systems, 2nd Edition The dielectric barrier between the two provides physical separation of the LED circuit (connected to the field device in a digital input circuit) and the phototransistor (connected to the PLC card circuit.) The correct answer is B, "to isolate the low-voltage circuitry on the digital input card from the field device voltage." An optical isolation circuit is used to provide a barrier between the field wiring and associated field wiring issues (shorts, ground loops, transients, etc.) In most PLC systems, this is accomplished with a special high-precision LED as a light source and a phototransistor as a receptor. The "optics" in answer C refers to environmental light, which is not a factor in a PLC input circuit, and answer D refers to the normal isolation of positive and negative terminals in an electrical circuit. This choice describes a feature of PLC cards, which do not have channel-to-channel isolation.Īnswers C and D do not have any relation to the "optics" or "isolation" that is provided by an optical isolator. The main purpose of an optical isolation circuit on a digital input card in a PLC I/O system is:Ī) to provide a common reference point for DC signalsī) to isolate the low-voltage circuitry on the digital input card from the field device voltageĬ) to block light from the surroundings in order to prevent the digital input card from overheatingĭ) to isolate the positive and negative terminals on the digital input cardĪnswer A is not correct. Click this link for more information about the CCST program. Certified Control System Technicians calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables. This automation industry quiz question comes from the ISA Certified Control Systems Technician (CCST) program. AutoQuiz is edited by Joel Don, ISA's social media community manager. ![]()
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