A Comprehensive Understanding of Tunable DWDM Transceiver

Posted on March 9, 2020
July 8, 2020

Tunable DWDM transceivers allow users to tune their wavelengths based on actual network demand. This results in the reduction in the number of spare transceivers that used for avoiding DWDM network breakdown, and offers flexibility to adapt to the growing network. On the market, tunable modules mainly include 10G SFP+, XFP and 25G SFP28 tunable DWDM transceivers. Then, are there any differences between the tunable 10/25G and standard 10/25G DWDM modules? This post will explain their differences in working principle, application and cost, then use FS box to show how to change the wavelength of the DWDM tunable transceiver.

Tunable DWDM vs Fixed-wavelength DWDM Transceiver

Working principle, application and cost are the main differences between tunable and fixed-wavelength DWDM transceivers.

Working Principle

Each fixed-wavelength DWDM module is designed with a specific wavelength, so the module can only be deployed in the network node that requires the corresponding wavelength. For example, an SFP+ transceiver with C21 wavelength can only work with the port of C21 wavelength on a DWDM MUX. But with the tunable SFP+ fiber module, users can use the module to connect any ports of the same DWDM MUX through fiber cables since the wavelength of the tunable transceiver can be tuned to adapt to the different port wavelengths.


With different working principles, standard DWDM optical modules are traditionally deployed in networks that require little channel change or addition. While tunable DWDM optical transceivers are envisioned to serve as spare units to suit the networks that need to change the wavelength as businesses grow.


It's true that the cost of an individual fixed-wavelength transceiver is lower than a tunable DWDM module. But in the long run, tunable optics will reduce OPEX. For example, in a large 10G SFP+ DWDM system that includes more than hundreds of nodes with different wavelengths, users have to provide up to hundreds of backup standard DWDM SFP+ transceivers to avoid unnecessary breakdown, which will greatly increase the operating cost. In this case, tunable optics help reduce the demand for DWDM SFP+ transceiver inventory, which will reduce the cost and maximize network flexibility.

Use FS BOX to Tune Wavelengths of Tunable DWDM Transceiver

FS box can tune the wavelengths of tunable transceivers. It’s a device used to solve real-time compatibility needs and upgrade the transceiver firmware (visit FS Box Introduction to learn more). All the operations can be done on the FS Box Smart Cloud Platform after plugging the fiber module into the corresponding port of FS box. Users can find information about their plugged tunable transceiver on the page, including its current wavelength. They can select any available wavelength from the dropdown menu. Then, click“start”, and the tuning will be done. The following video shows the ways to check and tune the wavelength of an SFP+ tunable DWDM transceiver.

Tunable DWDM Module FAQ

1. 10G Tunable XFP vs SFP+ DWDM tranceiver, is there any difference?

Tunable SFP+ DWDM modules comply with SFP+ MSA, while 10G DWDM XFP optical modules use XFP MSA standard (check tunable DWDM Transceiver Datasheet to learn more). The size of SFP+ is smaller than 10G XFP. Users can choose a suitable 10G tunable module based on the ports of their devices. Note that, on the market, SFP+ is the mainstream design in the 10G network.

2. Are the wavelengths of tunable DWDM module and fixed-wavelength DWDM module the same?

Tunable DWDM transceiver module runs on 50GHz C band wavelength with 0.4nm spacing. And it usually supports channels from C16 to C61. But this depends on the network switch or router manufacturers (like Cisco, Juniper) and which channels it supports. Standard DWDM transceiver support 50GHz (0.4nm spacing) and 100GHz (0.8nm spacing) C band wavelength. And since the channels of 50GHz include the 100GHz channels, it means that tunable DWDM with 50GHz can work on 100GHz wavelength. Therefore, there is no big difference between them.