1.25G Dual-Port BiDi cSFP 40km Transceiver TX1310/RX1550: 1.25G-cSFP-40-AD

Our EDGEOPTIC 1.25G-cSFP-40-AD is a multi-vendor compatible dual-port compact SFP optical module designed for extended-reach Gigabit Ethernet networks requiring maximum port density. This cSFP transceiver houses two independent BiDi (Bidirectional) channels within a single standard SFP form factor, allowing network engineers to double connectivity capacity while minimizing both equipment footprint and fiber strand utilization across metropolitan distances.

The 1.25G-cSFP-40-AD operates with both channels transmitting at 1310nm wavelength and receiving at 1550nm, supporting data rates from 1.063 to 1.25 Gbps per channel. Each channel leverages BiDi technology through WDM (Wavelength Division Multiplexing) for full-duplex communication over a single fiber per port. This module must be paired with its complementary counterpart, the 1.25G-cSFP-40-BD (TX1550/RX1310), to establish proper bidirectional links.

The 40km transmission capability addresses network architectures requiring extended reach beyond typical 20km access deployments. Metropolitan ring networks, distributed campus environments spanning several kilometers, and carrier-grade aggregation links benefit from this extended distance specification. The enhanced reach is achieved through improved optical performance, with transmit power ranging from -5 to 0 dBm and receiver sensitivity of -24 dBm, delivering a guaranteed 19 dB optical link budget—a 5 dB improvement over 20km variants providing necessary margin for longer fiber spans.

The transceiver employs DFB (Distributed Feedback) laser transmitters combined with PIN photodiode receivers for each channel. Unlike the 20km AD variants that utilize FP lasers, this extended-reach module requires DFB technology for its superior spectral characteristics and wavelength stability over longer transmission paths. Operating at 1310nm where chromatic dispersion is minimal in standard single-mode fiber, the module tolerates 300-400 ps/nm dispersion, well within the requirements for 40km spans. As with all optical deployments, actual achievable distance depends on fiber plant quality, connector losses, and accumulated splice attenuation.

The 1.25G-cSFP-40-AD features a Double LC/UPC connector interface providing two independent optical ports within the compact housing. The electrical interface adheres to CSFP MSA Option 2 specifications, ensuring compatibility with host systems designed for compact SFP modules across multiple vendor platforms.

Full Digital Diagnostic Monitoring (DDM/DOM) functionality enables real-time monitoring of critical parameters including transmitted and received optical power for both channels, module temperature, laser bias current, and supply voltage. Comprehensive diagnostics become increasingly valuable for extended-reach deployments where fault isolation across longer distances requires detailed optical telemetry.

The module operates within standard commercial temperature range of 0 to 70°C, appropriate for controlled installations such as central offices and equipment rooms. A single +3.3V supply provides operating power.

Standards compliance includes IEEE 802.3z for Gigabit Ethernet, IEEE 802.3ah for 1000Base-BX applications, and 1G Fiber Channel at 1.0625 Gbps for storage networking. Regulatory certifications include CE marking, RoHS compliance, and Class 1 laser safety ratings per FDA and IEC 60825-1.

Typical applications encompass metropolitan access networks, extended enterprise campus backbones, service provider aggregation points, and inter-site connectivity where 40km reach combined with dual-channel density optimizes both infrastructure investment and operational efficiency.

Because our focus is providing top quality service, we perform comprehensive quality verification including dual-channel optical parameter measurements, connector cleanliness testing, and EEPROM memory data validation before delivery.