NTT advances all-photonic infrastructure with optical network digital twins

In the latest part of its Innovative Optical and Wireless Network (IOWN) project, designed to meet the growing needs of the hyper-connected business world of the future, NTT Corporation (NTT) has announced technology to visualise the state of end-to-end fibre-optic links without using measuring equipment, and furthermore said it has succeeded for the first time in demonstrating the world’s highest accuracy in a North American field-deployed environment simulating a commercial network.

The technology is designed to advance the realisation of digital twins in optical networks, and is expected to be applied to the fastestablishment and maintenance of end-to-end optical connections including the IOWN all-photonics network (APN).

Spearheaded by comms and IT giant NTT – and supported by Sony, Intel, Nvidia, Microsoft and other leading technology firms – the IOWN initiative envisions a future global communications infrastructure capable of enabling ultra-high-speed, high-capacity internet services utilising photonics-based technologies.

It aims to address the almost exponentially rising demand for data, and a commensurate rise in energy consumption due to the vast amounts of compute power required by future applications, in particular artificial intelligence (AI) and large language model (LLM) use cases. This network and information processing infrastructure includes terminals that can provide high-speed, high-capacity communication using technology focused on optics, as well as large computational resources.

NTT’s IOWN APN infrastructure is designed to enable high-capacity, low-latency and low power consumption communications through end-to-end optical connections without converting optical signals into electrical signals.

To maximise the data transmission capacity of optical networks, it’s necessary to closely monitor and control the state of fibre-optic links, such as optical signal power. To achieve this, the application of digital twins in optical networks is being widely studied.

The digital twin of an optical network is a virtual optical network reproduced in cyber space. By analysing and predicting its optical transmission performance, NTT said it’s possible to quickly predict failures and maximise the data transmission capacity of a real optical network.

Yet NTT pointed out that there are currently two issues to be addressed in the implementation of digital twins. First, to precisely replicate a real optical network, it said it was necessary to place a large number of sensors or dedicated measuring instruments at every optical node, which increases the time and cost of sensor installation and operation. In some cases, when network faults occur, highly skilled workers are required to perform on-site measurements using specialised instruments such as optical time domain reflectometers (OTDRs).

Second, when optical connections are made between remote user locations using the IOWN APN, the monitoring range of the fibre-optic link must be extended to the user sites. In such an optical network covering multiple organisations, NTT warned that it can become difficult to access sensor information such as optical signal power beyond administrative boundaries due to security issues.

NTT’s research is said to have yielded three main results. The first of these is the development of digital longitudinal monitoring (DLM), which visualises the end-to-end optical signal power along a fibre-optic link solely from the signal reaching an optical receiver installed at network endpoints in only a few minutes without the use of specialised measuring instruments.

The second outcome has been the creation of a four-dimensional optical power visualisation technology that NTT said extends the visualisation of optical signal power not only in the direction of distance, but also in the time, frequency and polarisation.

Finally, NTT said it has made the world’s first successful demonstration with the highest accuracy using North American field-deployed optical fibre and commercial optical transceiver in a joint experiment with Duke University and NEC Laboratories America.

Fundamentally, NTT said the results show that the measurement of the state of fibre-optic links, which is necessary for the construction of an optical network, can be performed only with optical transceivers by using DLM technology. This, it said, enables the simultaneous measurement of all optical fibres and amplifiers between customer sites without the need for dedicated measuring instruments, greatly reducing the time required to design optical connections and identify abnormalities.