Full-duplex single-core optical module

Full-duplex single-core optical modules, also known as BiDi SFP or QSFP transceivers, enable simultaneous bidirectional data transmission over a single optical fiber using wavelength division multiplexing (WDM).OverviewA full-duplex single-core optical module allows data to be transmitted and received at the same time over a single strand of optical fiber, unlike traditional duplex modules that require two fibers—one for transmitting (TX) and one for receiving (RX) data . These modules are commonly referred to as BiDi (bidirectional) SFP or QSFP modules and are widely used in environments where fiber resources are limited or expensive, such as data centers, metro networks, and enterprise campus links .How It WorksThe core technology behind these modules is Wavelength Division Multiplexing (WDM). Each module uses two distinct wavelengths: one for transmitting and another for receiving. For example, one end may transmit at 1310 nm and receive at 1550 nm, while the opposite end uses the complementary wavelengths . Inside the module, a WDM coupler separates and combines the wavelengths, allowing a single LC optical interface to carry both directions simultaneously . Each BiDi module typically integrates:DFB or FP laser for stable wavelength outputPIN photodiode receiver for signal detectionInternal WDM coupler to separate inbound and outbound optical paths This setup supports full-duplex communication while reducing fiber usage by up to 50% .BenefitsFiber Savings: Cuts fiber requirements in half, ideal for fiber-constrained networks Cost Efficiency: Reduces CAPEX and OPEX by minimizing fiber procurement, trenching, and maintenance High-Speed Transmission: Available in speeds from 1.25G SFP modules up to 100G QSFP28 modules Simplified Deployment: Fewer physical connections reduce cabling complexity and potential failure points Hot-Swappable & Standards-Compliant: Compatible with SFP/SFP+ MSA, QSFP28 standards, and common networking protocols ApplicationsFull-duplex single-core optical modules are particularly useful in:High-density data centers where fiber conservation is criticalMetro and campus networks with limited fiber availability5G fronthaul/midhaul links where fiber runs are expensive or constrainedEnterprise backbones requiring scalable, cost-effective optical connectivity ConclusionBiDi optical modules provide a practical, cost-effective solution for increasing network capacity without adding additional fiber. By leveraging WDM technology, they enable simultaneous bidirectional communication over a single fiber, reduce infrastructure costs, simplify deployment, and optimize fiber utilization, making them ideal for modern high-speed, high-density networking environments .