Optical Connections Magazine Spring 2023


Pilot Photonics demo’s widely tuneable laser

América Móvil, Telxius, to build next-gen subsea cable

Pilot Photonics has announced the availability of a widely tuneable laser module. The company says it is the only commercially available tuneable laser that offers the combination of nanosecond switching and narrow linewidth, solving a long-running challenge in the industry. Pilot Photonics’ laser is based on a monolithic InP chip fabricated on an active-passive platform. Electro-optic tuning with reverse-voltage bias of tuning sections allows mA-order dark currents and facilitates nanosecond switching speeds with low power dissipation. It offers more than 30nm of wavelength tuning range in either the C-band or the O-band, and linewidth of 150kHz. Currently available in 14-pin butterfly package or integrated into an OEM or laboratory instrument form-

factor module, the company is also developing a nano- iTLA module for high volume applications Pilot says widely tuneable semiconductor lasers can typically offer narrow linewidth, or fast tuning, but not both. In optical fibre sensing systems, electronically tuneable lasers have traditionally been used for their fast tunability over a wide tuning range which is achieved using a current injection tuning mechanism. However, these lasers exhibit linewidths that are unsuitable for demanding phase sensitive applications such as coherent optical communication and frequency modulated continuous wave (FMCW) LiDAR. Changing to a thermal tuning mechanism reduces the linewidth, but at the expense of switching speed which renders the laser unsuitable for some of these applications.

Latin American service provider América Móvil and infrastructure provider Telxius have announced the deployment of a new ultra-high-capacity subsea cable to link Guatemala and the United States, as part of the ongoing commitment of the two largest telecommunication groups in Latin America to improve global communications. Named AMX3 by América Móvil and Tikal by Telxius, the subsea cable will be the highest capacity undersea cable to connect Puerto

The supply contract is already in force with Alcatel Submarine Networks and provides options to increase capacity and to incorporate additional branching units to serve other destinations. Tikal is the seventh new next-generation cable to complete its network since 2018 in addition to Brusa, Mistral, Tannat, Junior, Marea and Dunant. This means a multi-terabit, robust set of new next- generation subsea cables fully serving the Americas and Europe while enhancing Telxius traditional routes. Overall, Telxius will feature a 82,000 km network that has been designed to connect the main digital data hubs on both sides of the Atlantic. The cable is expected to go live in 2025.

Barrios in Guatemala, with Boca Raton in the US, with an additional

possible landing in Cancun (Mexico). Featuring an initial estimated capacity of 190 Tbps, the cable will serve a key route in the Caribbean.

Researchers perform aerial sensing over 524km

In a new field trial, researchers have shown that a real-time coherent transceiver prototype can be used for continuous sensing over a 524km live network aerial fibre wound around high-voltage power cables suspended from outdoor poles. In the new work, the researchers used a field-programmable gate array coherent transceiver sensing prototype for continuous fibre sensing by using information extracted from the coherent DSP. They used the DSP-based timing recovery module as a time- of-flight sensor. Using this approach, the researchers continuously monitored a

524-km length of aerial fibre for 70 hours using time- of-flight measurements. They correlated the sensing measurements with temperatures acquired from stations along the network link. The analysis revealed strong oscillations driven by polarisation changes over 50Hz, likely from the Faraday effect induced by the spun fibre. They demonstrated polarisation sensing of various wind conditions by filtering out the low-frequency portion of these polarisation changes. The results show that coherent transceivers could potentially be used to perform continuous sensing

over aerial fibres, making it possible to perform both environmental and network sensing using existing aerial fibres. Researchers say that by monitoring polarisation changes in the light traveling through a fibre link, this approach could enable new environmental or current sensing types. It can also be used to improve network integrity by continuously monitoring the health of the fibre link, for example, by detecting increases in fibre length that might indicate a pole is starting to tilt. Nokia Bell Labs’ Mikael Mazur, who will present the new findings at OFC

commented, “Optical fibres are everywhere, and if we can expand the use of this infrastructure to create a dense worldwide spanning mesh of environmental sensors, these communication systems can play an even bigger role in our daily life. Sensing transceivers can prevent service interruption and improve our understanding of the environment by significantly scaling the number of sensors without the cost of a dedicated sensing system. Most importantly, this can be done without any loss in data throughput, enabling full use of the communication system for its intended purpose.”


| ISSUE 32 | Q1 2023


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