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Tunable Optical Transceivers: What are they and when should they be used?

March 14, 2019

Tuneable optical transceivers for DWDM (Dense Wavelength Division Multiplexer) systems, such as XFP and SFP+, have been widely available within the telecommunications industry for a number of years. In this article, we detail exactly what tunable optical transceivers are, how they work and when they should be used.

What is a tunable optical transceiver?

Tunable optical transceivers are similar in operation and appearance to fixed transceivers, however they have the added capability of allowing you to set the channel (or colour) of the emitting laser. This reduces the need to have multiple devices that each operate at fixed wavelengths installed within a network. Instead, you have one transceiver that can be tuned according to the requirements of the operator.

Tunable transceivers are only available in DWDM form, because of the format of the dense wavelength grid. Typical tunable optics are designed for the C-Band 50GHz. They support approximately 88 channels which are set with a 0.4nm interval. They usually start from channel 16 and go up to 61, but this is dependent on the manufacturer of the router or switch and which channels it supports.

There are two main types of tunable transceivers:

XFP Tunable

Tunable XFP transeviers are designed with an integrated full C-Band tunable transmitter and high-performance receiver. This means that wavelengths can be set as default in the 50GHz DWDM grid. With single mode fiber, XFP tunable transceivers can operate at distances up to 80km.

Depending on the manufacturer, the names for these products can vary even though they have the same operational features.

These optics can be tuned in different ways. Most devices make it possible to tune over the CLI (Command Line Interface), but not every switch or router is capable of this.

SFP+ Tunable

Tunable SFP+ transceivers are full duplex, serial optical devices. The transmit and receive functions are contained within a single module which provides a high-speed serial link at 9.95 to 11.3Gbps signalling rates.

Again, these products can operate at distances of up to 80km with single mode fiber.

When should tunable optical transceivers be used?

Tunable transceivers are mostly kept as spare parts.

If, for example, you are running a large scale DWDM network with various nodes located in lots of places, and you are using up to 80 different wavelengths (with 50GHz spacing), with fixed transceivers you would need a few spares for each wavelength. This would result in huge amounts of stock and complex stock management processes. With tunable optics, the number of devices is significantly reduced, lowering storage and management costs.

They are often more expensive than fixed transceivers but savings are made in large networks where tunable transceivers are used to replace multiple fixed wavelength products.

What are the benefits of tunable transceivers?

As technology has progressed, tunable transceivers have improved drastically. They are now very popular within DWDM transmission systems because of their capabilities and ease of use.

The key benefits are:

  • Wide tuning range
  • Suitable for 100G systems because of reduced line-width
  • Convenience of wavelength adjustment depending on transmitting needs
  • Reprogramming takes seconds
  • Saves money in the long term

Summary

Tunable optical transceivers are able to operate at various wavelengths and adjust their wavelength according to each users’ needs. They are very popular in DWDM systems due to cost-saving factors and flexibility of use.

At Carritech, we stock and support a full range of optical transceiver products. To view our stock, learn more about our products or enquire about purchasing visit our optical transceiver page.

For more information on any of the information in the article, contact us at contact@carritech.com or call +44 0203 005 1170.

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