Sri Lanka Single-Fiber Bidirectional NRZ

Single-Fiber Bidirectional (BiDi) NRZ technology enables full-duplex data transmission over a single optical fiber in Sri Lanka, using two wavelengths and NRZ line coding for efficient, cost-effective connectivity.Overview of BiDi TechnologyBiDi optical modules allow simultaneous transmission and reception over a single fiber strand by using two distinct wavelengths, typically 1310 nm for transmitting (Tx) and 1550 nm for receiving (Rx) signals, separated via Wavelength Division Multiplexing (WDM). This approach eliminates the need for a second fiber, reducing fiber usage by up to 50%, lowering installation costs, and simplifying network management . BiDi modules are particularly useful in environments where fiber availability is limited or expensive, such as urban areas in Colombo or interconnecting campus networks in Sri Lanka .NRZ Line CodingNon-Return-to-Zero (NRZ) is a line coding technique where binary '1' and '0' are represented by constant voltage levels throughout the bit period. In unipolar NRZ, a '1' is a positive pulse and a '0' is zero voltage, while in polar NRZ, a '1' is positive and a '0' is negative . NRZ coding is widely used in optical communication because it is bandwidth-efficient, reduces inter-symbol interference, and is compatible with high-speed BiDi transceivers.Applications in Sri LankaSri Lanka is rapidly expanding its fiber optic infrastructure to support 5G, IoT, e-commerce, and smart city initiatives. Deploying BiDi NRZ systems can:Maximize existing fiber infrastructure without laying additional cables, which is cost-effective for telecom operators like SLT-Mobitel and Dialog Axiata .Support high-speed, low-latency connections for data centers, metro rings, and campus networks.Simplify network upgrades by reducing physical connections and potential failure points .Technical ConsiderationsOptical Isolation: BiDi modules include integrated filters to prevent crosstalk between Tx and Rx wavelengths, ensuring data integrity .Matched Pairs: Devices must be compatible with BiDi SFP modules to maintain full-duplex communication.Distance and Speed: NRZ coding supports high-speed transmission over moderate distances, making it suitable for urban and regional networks in Sri Lanka .ConclusionSingle-Fiber Bidirectional NRZ technology is a practical and efficient solution for Sri Lanka's growing digital infrastructure. By combining BiDi transceivers with NRZ line coding, network operators can achieve full-duplex communication over a single fiber, reduce costs, and enhance bandwidth utilization, supporting the country's digital economy and next-generation network initiatives .