1.25G BiDi 1×9 Optical Transceiver Module is a Gigabit-speed single-fiber bidirectional transceiver in the compact 1×9 pin-package format. Using WDM (Wavelength Division Multiplexing) technology, it simultaneously transmits and receives 1.25Gbps data on a single optical fiber strand by assigning different wavelengths to the TX and RX directions — eliminating the need for a conventional fiber pair and halving fiber infrastructure requirements.

Available with metal SC, FC, and ST optical interfaces, as well as pigtail variants, the module accepts selectable +3.3V or +5.0V single power supply. Two wavelength pair groups are offered: 1310nm/1550nm for 20–60km links, and 1490nm/1550nm for 60–120km long-distance links. Hot-swap capability allows live module replacement without powering down the host system.

Three temperature grades address different deployment environments: Standard C (0°C to +70°C) for indoor equipment, Extended (–20°C to +85°C) for semi-outdoor or mildly harsh environments, and Industrial I (–40°C to +85°C) for outdoor cabinets, industrial floors, rail trackside, and other demanding installations. The module supports Fast Ethernet, Gigabit Ethernet (1000BASE-BX), Fiber Channel, and other 1.25G fiber link standards.

Technical Specs Summary

Key Features

1.25Gbps BiDi — single-fiber full-duplex Gigabit transmission

WDM technology — internal wavelength MUX/DEMUX filter

Hot-swappable — live replacement without system downtime

1×9 pin package — compact direct PCB-mount format

Metal SC / FC / ST interfaces; Pigtail option available

Wavelengths: 1310nm/1550nm (20–60km) and 1490nm/1550nm (60–120km)

Single-mode fiber distances: 20km / 40km / 60km / 120km

Power supply: +3.3V or +5.0V selectable

Logic: LVTTL  |  LVPECL signal detect output

Three temperature grades: Standard / Extended / Industrial

Applications: Gigabit Ethernet / 1000BASE-BX / Fiber Channel

Technical Advantages

1.25Gbps — 8× the Data Rate of the 155M 1×9 BiDi Series

At 1.25Gbps, this module delivers the full Gigabit Ethernet data rate in the same 1×9 BiDi form factor as the 155M series. This makes it the direct upgrade path for installations that require Gigabit performance on existing single-fiber plant infrastructure, without changing the physical connector type or fiber path.

Hot-Swap Support — Zero Downtime Maintenance

Unlike many 1×9 modules, this series supports hot swapping — the module can be inserted or removed while the host board is powered on without disrupting adjacent network channels or requiring a system restart. This is operationally significant in managed industrial Ethernet equipment and dense fiber patch environments where continuous uptime is required.

Three Temperature Grades — Standard, Extended, and Industrial

Most 1×9 BiDi modules offer only two temperature grades. This series adds an Extended grade (–20°C to +85°C) between Standard and Industrial, providing a more cost-optimized option for deployments that experience moderate cold but do not require full industrial qualification — such as unheated equipment rooms, semi-outdoor shelters, or warehouse automation systems.

120km Maximum Reach on Single-Mode Fiber

The 1490nm/1550nm wavelength pair variants achieve up to 120km single-fiber transmission, making this module suitable for metropolitan backbone links, cross-city fiber runs, and remote site connectivity at full Gigabit speeds — without optical amplification or repeaters.

Dual Power Supply: 3.3V and 5.0V

Selectable +3.3V or +5.0V power supply ensures compatibility with both modern low-voltage and legacy 5V industrial PCB designs, eliminating the need for a dedicated voltage regulation stage in OEM equipment boards.

BiDi Wavelength Pairing Reference

Install one Model A at the near end and one Model B at the far end. Do not use the same model at both ends.

1310/1550nm group: 20km, 40km, 60km.  |  1490/1550nm group: 60km, 120km.  |  Always verify TX/RX wavelength complementarity at both link ends before ordering.

 Typical Applications

Gigabit Ethernet single-fiber access and backbone links

1000BASE-BX compatible fiber plant deployments

Fiber Channel SAN single-fiber Gigabit connectivity

Metropolitan area network (MAN) single-fiber ring segments

Long-distance backbone links up to 120km at 1.25Gbps

Industrial Gigabit Ethernet single-fiber uplinks

OEM PCB-integrated Gigabit fiber transceiver for industrial equipment

Fiber infrastructure upgrades from 155M to 1.25G on existing single-fiber runs

Compatibility and Deployment

The 1×9 pin-package module mounts directly on the host PCB via through-hole pins, compatible with standard 1×9 PCB footprints used in Gigabit Ethernet equipment, Fiber Channel HBAs, and OEM industrial control boards. Metal SC/FC/ST connectors accept standard fiber patch cords; pigtail variants are available for direct fiber splicing.

Power supply voltage (3.3V or 5.0V) and temperature grade (C, –20, or I) are specified at order time. Connector type (SC, FC, ST) is encoded per Note 3. For pigtail variants, extended temperature configurations, or OEM volume support, contact our technical sales team.

FAQ Module 

Q: What is the difference between the 155M and 1.25G BiDi 1×9 modules?

A: The 1.25G BiDi 1×9 operates at 1.25Gbps — 8 times faster than the 155M version (155Mbps). Both use the same 1×9 BiDi WDM single-fiber format and the same wavelength pairs. The 1.25G version additionally supports hot swapping and adds a third Extended temperature grade (–20°C to +85°C) not available on the 155M series.

Q: Does this module support hot swapping?

A: Yes. The 1.25G BiDi 1×9 supports hot swapping — the module can be inserted or removed while the host board is powered on and operating. This allows field replacement or reconfiguration without system restart or service interruption to other network channels.

Q: What are the three temperature grades and which should I choose?

A: Standard C (0°C to +70°C) is for controlled indoor data center and equipment room environments. Extended (–20°C to +85°C) suits unheated indoor spaces, semi-outdoor shelters, or mild-climate outdoor equipment where full industrial qualification is not required. Industrial I (–40°C to +85°C) covers full outdoor, rail, industrial floor, and harsh-environment deployments.

Q: What is the maximum transmission distance?

A: Up to 120km over 9/125μm single-mode fiber using the 1490nm/1550nm wavelength pair models (GABx-4512-K2x / GABx-5412-K2x). Other distances: 20km, 40km, and 60km using the 1310nm/1550nm pair; 60km also available with 1490nm/1550nm pair.

Q: Do I need to order two different models for one BiDi link?

A: Yes — one Model A and one Model B must be installed at opposite ends of the fiber. The TX wavelength of Model A must equal the RX wavelength of Model B, and vice versa. Using the same model at both ends will result in a failed link. See the wavelength pairing table for the correct model combinations.

Q: Is this module compatible with 1000BASE-BX equipment?

A: Yes. The 1.25Gbps BiDi 1310nm/1550nm wavelength pair is compatible with the IEEE 802.3ah 1000BASE-BX10 standard used in Gigabit Ethernet equipment. The 1490nm/1550nm variants are used in ITU-T G.984 compliant GPON and other long-distance Gigabit fiber applications.

Ordering Information

10 models available. Part number codes: (1)=power; (2)=temp grade; (3)=interface type. See notes below.

Note 1:  (1) x=N → Power Supply 3.3V;  x=L → Power Supply 5.0V.

Note 2:  (2) x=space → 0°C to +70°C (Standard C);  x='–20' → –20°C to +85°C (Extended);  x=I → –40°C to +85°C (Industrial I).

Note 3:  (3) Interface: SC interface code 'F' (e.g. GABx-1312-02xF);  FC interface code 'T' (e.g. GABx-1312-02xT);  ST interface code '1' (e.g. GABx-1312-02x1).

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