MikroTik S-35LC20D BiDi SFP-module, 1,25G single-mode LC simplex, 20km, 1310nm/1550nm, DDM

Push a single strand of fiber to 20 kilometers with the MikroTik S-35LC20D, a bidirectional SFP that transmits at 1310nm and receives at 1550nm over one LC simplex connector. This 1.25G BiDi module halves your fiber infrastructure while doubling link density—ideal for long-haul Gigabit Ethernet where fiber is scarce.

Overview

The S-35LC20D is a hot-pluggable, MSA-compliant SFP transceiver engineered for single-mode fiber. It delivers full-duplex 1.25 Gbps throughput across distances up to 20 km using only one fiber strand, thanks to its integrated WDM (wavelength division multiplexing) design. Digital diagnostic monitoring (DDM) provides real-time visibility into optical power, temperature, and laser bias, so you can spot degradation before it becomes downtime.

What stands out

• BiDi technology: transmit and receive on a single fiber, cutting cabling costs and doubling port capacity.
• Long reach: 20 km over OS2 single-mode fiber—perfect for campus or metro links.
• DDM/DOM support: monitor optical parameters remotely via MikroTik RouterOS or any MSA-compatible host.
• Broad compatibility: works in any MikroTik SFP port and other MSA-compliant switches and routers.
• Low power: under 1W consumption, reducing heat and energy costs in dense deployments.

Technical details

• Form factor: SFP (Small Form-Factor Pluggable)
• Data rate: 1.25 Gbps (Gigabit Ethernet)
• Fiber type: Single-mode (SMF, OS2)
• Connector: LC simplex (single fiber)
• Wavelength: TX 1310nm / RX 1550nm (DFB laser, PIN receiver)
• Max distance: 20 km
• DDM/DOM: Yes
• Hot-pluggable: Yes
• Compliance: MSA, RoHS
• Power: 3.3V, <1W
• Operating temperature: 0°C to 70°C
• Storage temperature: -40°C to 85°C

Our verdict

If you need to stretch a Gigabit link across a campus or between buildings without pulling new fiber, the S-35LC20D is a smart, reliable choice. Its BiDi design and DDM monitoring make it a standout for cost-conscious network builders.