Optical Transceiver FAQ 2026: Choose 155M–2.67G BiDi SFP Modules for Single-Fiber Links in Southeast Asia

Key Takeaways for Selecting BiDi Optical Transceivers

Wavelength Division Multiplexing (WDM) is the operating principle behind a BiDi, or WDM SFP. One end transmits on one wavelength and receives on its paired, contrasting wavelength; the remote end does the reverse. Both directions therefore occupy one fibre simultaneously without colliding. In practice, this can halve the fibre strands required for a dedicated link and avoid a second cable pull.

Optone’s 155M–2.67G BiDi SFP optical transceivers cover 155M, 1.25G and 2.5G services, with model-dependent reaches from 3 km to 120 km. That range suits legacy SDH/SONET circuits, access aggregation and FTTx builds as well as older Ethernet equipment. Do not treat reach as a promise that any fibre route will work. It is a rated optical class, not a substitute for inspecting the route.

BiDi SFP FAQ: A/B Pairing, Wavelength Choices and Existing Fiber

Most BiDi purchasing mistakes are pairing mistakes. Unlike two conventional dual-fibre optics of the same type, two identical BiDi modules do not create a link. The transmit wavelength at one end must align with the receive wavelength specified for the other. Keep the pair together through receiving, staging and field installation; loose modules in a storeroom have caused more than a few avoidable truck rolls.

How do I select a matched A-End and B-End BiDi SFP pair?

Select one A-End and its explicitly specified B-End counterpart at the same data rate and reach class. A common pairing has one module transmitting at 1310 nm and receiving at 1550 nm, while the other transmits at 1550 nm and receives at 1310 nm. Confirm the labels, part numbers and optical directions on the datasheet rather than relying on an installer’s shorthand. Both ends also need compatible host ports and the same service requirement. A 1.25G pair is not an upgrade path for a 155M port simply because both use the SFP form factor.

When should I use 1310/1550 nm versus 1490/1550 nm, and does BiDi SFP require single-mode fiber?

Use the wavelength pair required by the deployed equipment, network design or existing matched endpoint. There is no universal “better” pair: 1310/1550 nm and 1490/1550 nm are separate optical plans, and their ends cannot be mixed. BiDi SFP modules in this Optone range are intended for single-mode fibre. Verify the installed cable type, particularly on older campus or building links where documentation can be unreliable. A single unused strand is enough for the link, but it must be continuous through the patch panels and correctly terminated with the required simplex connector.

155M–2.67G BiDi SFP Specifications to Compare Before Requesting a Quote

A useful RFQ describes the application, not just “BiDi SFP, 20 km.” State the port rate, the wavelength pair required, route length, available fibre type, connector interface and whether the switch, router, OLT or transmission shelf checks vendor coding. For network operators, include the service protocol: SDH/SONET and Ethernet ports can have different expectations even at similar nominal rates.

Optone offers complementary A-End/B-End options across this portfolio. Some models use Simplex LC and others Simplex SC connectors. That detail is easy to miss until the modules arrive and cannot mate with the existing patch lead. Review the product options for the single-fibre BiDi SFP range against the actual panel interface.

Comparison Table: Data Rate, Reach, Wavelength Pair and Simplex Connector Options

The table is a buying framework, not a substitute for the module-specific datasheet. Reach and connector availability depend on the selected Optone model.

Selection item	Available scope	What you should confirm
Data rate	155M, 1.25G, 2.5G	Native port and service rate
Reach	3 km to 120 km, model dependent	Route loss, splices, patching and reserve margin
Wavelength pair	Complementary 1310/1550 nm or 1490/1550 nm options	Correct A-End/B-End orientation at both sites
Connector	Simplex LC or SC, model dependent	Existing patch panel and jumper connector

Why Link Budget, Receiver Sensitivity, Optical Power and DOM/DDM Matter

Rated distance alone is a poor acceptance criterion. The loss accumulated in fibre, fusion splices, mechanical joins, splitters where present and dirty patch connections must fall within the module pair’s supported optical range. Receiver sensitivity defines how weak a signal can be before reliable detection fails; excessive received power can also be a concern on short, low-loss routes with higher-power optics. Ask for the transmit-power and receive specifications for the exact part number.

Modules compliant with SFF-8472 can provide digital diagnostics monitoring, often called DDM or DOM. Readouts for transmit power, received power, temperature, supply voltage and laser bias can help you distinguish a dirty connector from a degrading optical path. Diagnostics are useful only if the host platform exposes them, so verify that point early.

How to Select and Validate a BiDi SFP for an Installed Network Link

Field validation should happen before the maintenance window, not during it. Installed links across industrial estates, high-rise buildings and island access sites often contain undocumented patch changes. A module that worked on the bench may fail after passing through a panel with an SC adaptor, an ageing jumper or a contaminated ferrule.

Confirm the Platform Port, Required Rate, Fiber Type and Connector

Start with the port documentation and the current optic, if one is installed. Then follow a disciplined check:

1. Record the host device make, model, port type and required service rate.
2. Identify the fibre as single-mode and trace the available strand from end to end.
3. Confirm whether the local patching uses simplex LC or SC.
4. Select the complementary A-End/B-End wavelengths and a reach class appropriate for the measured route condition.
5. Clean and inspect connectors before commissioning, then review received-power diagnostics where supported.

Do not use a high-reach optic merely because it is available. It may be appropriate for the route, but the decision should follow the optical requirements and the receiver limits of the selected pair.

Verify OEM Coding, Diagnostics Requirements and End-to-End Compatibility

Many switches and transmission platforms inspect EEPROM vendor information before enabling an optic. Specify the host make and platform model so OEM-compatible coding can be confirmed. Optone modules are MSA-compliant, but MSA mechanical and electrical compliance does not remove every vendor acceptance rule. The far-end device matters just as much as the local one.

Confirm SFF-8472 diagnostics support if your NOC needs DOM/DDM readings for commissioning or ongoing fault isolation. Finally, test both ends as a pair on the intended equipment where possible. This catches coding rejection, swapped A/B modules, unsupported monitoring and connector mismatch before the installation crew is on site.

Request Optone 155M–2.67G BiDi SFP Guidance and a Project Quote: https://fibertransceiver.com/products/optical-transceivers/155m-2-67g-bidi-sfp/

Send the device models at both ends, required rate, fibre route details, preferred wavelength plan, connector type and quantity. If you have optical test records or DOM readings from the current link, include them. They are far more useful than a distance estimate copied from an old drawing.