Ukrainian Single-Fiber Bidirectional QSFP

Single-fiber bidirectional QSFP modules provide 100G full-duplex connectivity over a single SMF, saving fiber resources while supporting high-speed data center, enterprise, and telecom applications. OverviewSingle-fiber bidirectional (BiDi) QSFP transceivers use wavelength division multiplexing (WDM) to transmit and receive data simultaneously over a single optical fiber. This approach reduces fiber usage by 50% compared to traditional duplex modules, which require separate fibers for transmit and receive signals.

These modules are typically hot-swappable, compact (QSFP28 form factor), and compatible with high-density switch ports, making them ideal for network upgrades without extensive cabling changes.

Key Specifications

Data Rate: 100Gbps full-duplexFiber Type: Single-mode fiber (SMF)Distance: Up to 20 km for Cisco QSFP-100G-B20U4-I/B20D4-I; other modules can range from 10 km to 30 km depending on model Wavelengths: Typically two wavelengths per fiber (e.g., 1270/1330 nm or 1296/1309 nm) for bidirectional transmission Modulation: NRZ (Non-Return-to-Zero) for Cisco modules; PAM4 (four-level pulse amplitude modulation) for some QSFP28 BIDI modules to increase bandwidth efficiency Connector: LC duplex interfaceCompatibility: Works in QSFP28 ports and interoperates with mainstream switch brands Operational PrinciplesCisco QSFP-100G-B20U4-I and B20D4-I modules operate in pairs, with one transceiver at each end of the fiber.

Each module contains four transmitters and four receivers, multiplexed into a single fiber using a diplexer filter, enabling full-duplex 100G transmission over a single fiber. Using two pairs on the same fiber can provide 200Gbps bandwidth and network resiliency.

YX

Fiber QSFP28-BIDI modules achieve bidirectional transmission by assigning uplink and downlink wavelengths to the same fiber, preventing interference and allowing simultaneous two-way communication. PAM4 modulation doubles the data rate per wavelength compared to NRZ, supporting 100G over a single fiber efficiently.

Applications

Data Centers: High-density interconnects, regional or metro linksTelecom Operators: Aggregating 4G/5G front-, mid-, and backhaul trafficEnterprise Networks: Connecting metro offices or campus buildingsService Providers: Linking business customers to central offices or headendsAdvantagesReduces fiber infrastructure costs by using a single fiber for bidirectional trafficSupports long-distance 100G transmission (up to 20 km or more)Compatible with existing QSFP28 ports and mainstream switchesProvides network resiliency when deployed in redundant pairs In summary, Ukrainian single-fiber bidirectional QSFP transceivers are high-performance, fiber-efficient modules suitable for modern high-speed networks, leveraging WDM and advanced modulation to deliver 100G full-duplex connectivity over a single SMF, with applications spanning data centers, telecom, and enterprise networks.