19. November 2021

Tunable DWDM transceiver

Introduction to Tunable DWDM Transceivers

Thanks to the use of Tunable DWDM transceivers, users can adapt the transceiver wavelength to the requirements of their network. Thus, Tunable transceivers offer greater flexibility than standard transceivers with fixed wavelengths, as they can optimally serve a growing and scalable network.

In this article we will inform you comprehensively about the differences between standard and Tunable DWDM modules.

Standard vs. Tunable DWDM Module

DWDM transceivers with a fixed wavelength are ideally suited for operation within the band of a specific wavelength. They are preferably used in static networks in which no changes are expected in the future.

The wavelength of a Tunable DWDM transceiver, on the other hand, can be set individually. These flexibly deployable transceiver modules are primarily aimed at carriers, ISPs and data center operators - in other words, at customers whose networks have a certain dynamism and are expected to grow further in the future.

Consider, for example, an SFP+ transceiver: the main difference between fixed wavelength transceivers and Tunable transceivers is that the wavelength of DWDM SFP+ transceivers is fixed and unchangeable, while the Tunable SFP+ variant can adjust its wavelength on site to the desired lambda.

Tunable DWDM SFP+ transceivers allow the wavelength to be changed indefinitely within the C-band DWDM ITU grid and can be used in various types of equipment such as switches, routers, servers and in Pan Dacom Direkt's DWDM system.


Tunable DWDM transceivers are widely used in the data communications and networking industry. Unlike conventional or standard modules, Tunable modules are used in dynamic network environments where future changes cannot be ruled out so as to be able to absorb network dynamics.

Tunable transceivers are therefore the first choice for those operating a large DWDM network with multiple nodes. Let's assume that up to 80 different wavelengths are to be used. In this case, a large stock of spare parts would be needed to promptly replace a defective fixed wavelength transceiver with a new one in case of equipment failure. Tunable transceivers are a good solution for better inventory management in such cases. A single Tunable Transceiver can be kept in stock as a spare part for almost any fixed wavelength optical transceiver. This reduces the overall cost of stocking spare parts.

In the 10G range, Tunable Transceivers are offered for this purpose as SFP+ and XFP, and in the 100/200/400G range as CFP/CFP2 form factor.

Types of tunable transceivers

There are two common types of Tunable Transceivers, which we would like to introduce here:

Tunable XFP Transceivers

Tunable XFP transceivers work with an integrated adjustable C-band transmitter and a powerful receiver. This allows these modules to be configured to operate at any wavelength in the 50 GHz DWDM grid. When using single-mode fiber, Tuneable XFP transceivers can cover distances of up to 80 km.

Tunable SFP+ Transceiver

Tunable SFP+ transceivers belong to the serial optical devices and have full duplex capability. A single housing contains both the transmitter and the receiver of these modules, enabling a high-speed serial connection with signal transmission rates between 9.95 Gbps and 11.3 Gbps. In terms of distances to be bridged, tunable SFP+ transceivers are just as effective as tunable XFP transceivers.

Tunable modules & costs

Indeed, tunable modules cost more than fixed wavelength modules. But the investment is worth it. With these modules, the cost of spare parts inventory can be effectively reduced and dynamic networks can be operated in a cost-saving manner.


  • extensive tuning range (wavelength)
  • compatible transceivers from 10G to 400G
  • simplified spare parts stocking
  • software adjustable wavelength
  • high cost efficiency in the long term


Tunable DWDM transceivers are designed to operate at customer-specific and dynamically changing wavelengths. Despite the higher initial costs compared to modules with fixed wavelengths, tunable transceivers quickly prove to be advantageous in large DWDM networks. In this way, sometimes up to hundreds of fixed wavelength transceivers can be replaced by just one tunable transceiver.