Single fiber power
The ability to send and receive data simultaneously in a single fiber is a technology that ensures full duplex operation without the cost of purchasing or leasing an additional fiber.
This has a major economic impact on the functioning of networks of telecommunications operators, as well as Internet providers or public sector institutions.
Willingness to take advantage of single-fiber technology can result from both limited fibre resources and the cost of renting them in the event that we do not have our own fibres for a particular project. It may also be the case that we have been using solutions based on a single optical fiber in our network for years.
The challenge we face today is to launch a transmission with bitrate 40 GbE or 100 GbE based on the infrastructure you have. Whether it is a new project or an extension of an existing one, the realization of high bitrates per fiber is not a trivial task.
To begin with, we need to ensure that we can send and receive data simultaneously in a single fiber. Help comes to us wave multiplication technology. In our solutions, we will focus on DWDM technology, since only it allows to realize bitrates such as 40 GbE or 100 GbE natively. But also one fiber at a time?
To answer this question, we need to take a closer look at the construction of commercially available optical inserts. From previous articles we already know that the implementation of the required bitrates will allow us CFP/CFP2 Coherent Inserts and QSFP28 DWDM inserts. However, do they allow you to work on a single optical fiber?
In the CFP/CFP2 standard coherent insert, the key elements are modulator PM-QPSK and an integrated PM-QPSK receiver, but both systems require a tunable laser to be connected to it, as shown in the simplified diagram below.
Therefore, if we make the connection exactly according to the figure below, it means that both transmission and reception must take place at the same wavelength, which discredits this solution as potential for use in single-fiber transmission.
Of course, it is technically possible to make an optical module, which will have two independent modules tunable laser and thus enable the transmitter to operate at a different wavelength than the receiver. In practice, however, this is a solution that would significantly increase the price of the module and, unfortunately, such modules are not produced.
And what does it look like in a QSFP28 DWDM insert? As we already know from the article (DCI), these inserts work in DWDM technology and are compatible with the 100 GHz network. The scheme of their operation is presented in the diagram below.
The fundamental difference is that the receiving system does not have to have a connection to the laser source, therefore the wavelengths of the receiver and transmitter do not have to be the same. Different wavelengths are a necessary requirement, to enable the connection of a single optical fiber.
Single fiber allows connections to be made even at high speeds 100GbE. Moreover, the use of DWDM technology allows you to transmit several such streams as well. For this we need to use a properly prepared optical line and QSFP28 DWDM inserts. 100GbE and a single optical fiber... sounds like an optimization of OPEX.
Want to know what else you can transmit with just one fiber? Feel free to contact us.