1.25G SFP BiDi 1550/1310 TX/RX Optical Transceiver Module
Product Overview
The Apex 1.25G SFP BiDi module carries one Gigabit link over a single strand of single mode fiber. The transmitter runs at 1550nm and the receiver at 1310nm, so a working link is built from two matched modules: one with 1550nm TX / 1310nm RX and its partner with 1310nm TX / 1550nm RX.
Because each direction gets its own wavelength instead of its own fiber, a BiDi link uses one simplex LC run instead of a duplex pair. That matters in access and metro builds where fiber is the scarce and expensive part: one strand can serve a customer, a camera or an OLT uplink while the second strand stays free for another service or for a future 10G upgrade.
Every unit is burnt in and tested for optical power and error rate, supports digital diagnostics over the DDM interface, and is coded for the platform you name before it leaves the warehouse. Reach options cover 10km, 20km and 40km on standard single mode fiber, with 60km and 80km builds available on request.
Key Features
- 1.25Gbps Gigabit Ethernet and SDH STM-1 / OC-3 line rate
- SFP MSA hot pluggable package, single fiber BiDi design
- 1550nm transmitter / 1310nm receiver, matched partner module required
- Reach options of 10km, 20km and 40km over single mode fiber
- Simplex LC interface, one fiber strand per link
- Digital Diagnostic Monitoring (DDM/DOM) for live optical readings
- Commercially coded for the switch, OLT or router platform before shipment
- RoHS compliant, single 3.3V supply
Technical Specifications
| Specification | Detail |
|---|
| Part Number | APX-SFP-1.25G-xxKM-BIDI (xx = reach) |
| Manufacturer | Apex |
| Data Rate | 1.25Gbps |
| Form Factor | SFP, hot pluggable |
| Optical Technology | BiDi, single fiber bidirectional |
| Wavelength | 1550nm TX / 1310nm RX (partner unit 1310nm TX / 1550nm RX) |
| Reach Options | 10km, 20km, 40km; 60km and 80km on request |
| Fiber Type | Single Mode Fiber (SMF) |
| Connector Type | LC simplex |
| DDM / DOM | Supported |
| Supply Voltage | 3.3V |
| Compliance | SFP MSA, RoHS |
| Temperature | 0 to 70C commercial, -40 to 85C industrial on request |
Ordering Options
Family options are listed below as plain text so they can be copied into an RFQ or a spreadsheet.
| Ordering code | Wavelength pair | Reach | Interface |
|---|
| APX-SFP-1.25G-10km-BIDI-55 | 1550nm TX / 1310nm RX | 10km | LC simplex |
| APX-SFP-1.25G-10km-BIDI-31 | 1310nm TX / 1550nm RX | 10km | LC simplex |
| APX-SFP-1.25G-20km-BIDI-55 | 1550nm TX / 1310nm RX | 20km | LC simplex |
| APX-SFP-1.25G-20km-BIDI-31 | 1310nm TX / 1550nm RX | 20km | LC simplex |
| APX-SFP-1.25G-40km-BIDI-55 | 1550nm TX / 1310nm RX | 40km | LC simplex |
| APX-SFP-1.25G-40km-BIDI-31 | 1310nm TX / 1550nm RX | 40km | LC simplex |
Applications
FTTH and Access Uplinks
Connects OLT ports to ONUs and access aggregation sites where only one strand of fiber reaches the subscriber or the street cabinet.
Metro and Enterprise Single Fiber Runs
Builds Gigabit links between buildings and metro nodes when the duct or cable has a single spare strand and pulling new fiber is not an option.
Industrial and CCTV Networks
Carries 1.25G video and control traffic over long single fiber runs in plants, campuses and utilities, with industrial temperature versions for outdoor cabinets.
Compatibility
1.25G BiDi modules are coded to the host platform you specify, including OLT equipment, carrier Ethernet switches and enterprise routers, and are tested on live ports before shipment. Because BiDi links depend on two matched wavelengths, we quote the pair together and label each unit A or B so field teams cannot mix them up.
Related Products
Frequently Asked Questions
What does 1550/1310 TX/RX mean?
It means the transmitter works at 1550nm and the receiver at 1310nm. The module at the other end of the link is the opposite type, 1310nm TX and 1550nm RX, so the two wavelengths travel in opposite directions on the same strand.
Can one BiDi module work on its own?
No. A BiDi link needs a matched pair, one 1550/1310 unit and one 1310/1550 unit, and the optics only come up when both ends are fitted. We ship and label them as a pair.
How much fiber does a BiDi link save?
Half of a duplex link. A duplex 1.25G link needs two strands, one for each direction, while a BiDi link needs one strand and keeps the second strand free for another service or a later upgrade.
Do you stock 1.25G BiDi modules?
Yes. We hold stock on the common 10km, 20km and 40km BiDi variants and quote the same day on request. Longer reaches are built to order.
Why Choose Apex
- Optical engineering support and supply from 1.25G to 800G, including BiDi, WDM and coherent lines.
- Every module is tested for optical power, error rate and interoperability before it ships.
- Matched BiDi pairs are shipped and labelled together so installation is unambiguous.
- Backed by a 3 year warranty and technical support before and after the sale.
