Communications

Advanced OSAs are the path to sustainable growth in data

by Kelvin Hagebeuk October 5, 2021

With Glasgow hosting the UN’s latest climate change conference, COP26, the need to rein in CO₂ emissions to protect the environment is very much in the headlines.

At COP26 there will no doubt be a lot of discussion of promoting the use of electric vehicles and switching over to non-fossil fuel sources of energy such as nuclear, wind and solar.

Possibly one of the few good things about the pandemic was the need to ramp up the switch to working from home instead of using polluting transport to commute to the office, while furloughed people spent a lot of time on streaming services like Netflix. I remember in the early days of lock down seeing many service providers updating their network to deal with the expected increased demand.

Yet the pandemic simply boosted an underlying trend that has been building for years. An increasing number of mobile users, as well as many more data-heavy mobile industrial applications, is producing an explosion in data traffic. In fact, by the end of this year, over half a billion 5G mobile subscriptions are expected, with 3.5 billion by the end of 2026. Web traffic is also set to double by 2022.

We may think that, with people using digital and mobile instead of transport, the problem of pollution is on its way to being solved. Unfortunately, things are not that simple. The greater amount of traffic means a growing number of telecommunication installations in the networks and ever more data centres. These still use electricity and so cause carbon emissions. In fact, the Royal Society has estimated that digital technologies could be responsible for nearly six percent of greenhouse gas emissions.

Clearly, we need to deal with the emissions caused by this growing use of networks. As I see it, there are two main ways to tackle the issue. One is to make greater use of those sustainable energy sources I mentioned.

The other is to use networks more efficiently – this involves getting more data through the same pipe without building more energy consuming infrastructure. The key to this increased efficiency is Dense Wavelength Division Multiplexing (DWDM), an optical multiplexing technology used to increase bandwidth over the existing optical fiber backhaul network.

With the huge increase in data traffic as we move more of our lives online, many more frequencies will need to be squeezed through the same optical pipelines. Measuring and analyzing these waveforms is vital to developing the next generation of optical components that will keep the traffic flowing.

For many years, researchers have relied on Optical Spectrum Analyzers, or OSAs, to perform this analysis. OSAs are designed to measure and display the distribution of power of an optical source over a specified wavelength span. When developing ever denser DWDM systems, a typical use could be the measurement and analysis of a multiplexed optical signal carrying multiple communication channels over a single fibre.

With the need to measure and analyse a growing number of wavelengths, are current OSAs really up to the job?

The crunch factor is resolution – development engineers need an OSA that can separate closely allocated communication channels and modulation side peaks of optical transceivers. With those wavelengths getting ever closer, standard OSAs are struggling.

Step forward Yokogawa’s new AQ6380 – with a resolution down to 5 picometers, developers can be confident that optical signals in close proximity can be clearly separated and accurately measured.

With the AQ6380, waveforms that were previously not even visible in a typical OSA, such as modulation side peaks in the laser spectrum, can now be accurately visualized.

There is also the cost factor. R&D can be an expensive pursuit, so developers don’t want to have to purchase more OSAs than needed. The AQ6380 meets this ambition by offering a range of wavelengths from 1200 to 1650 nm, allowing one unit to meet diverse wavelength measurement needs. It can also alter the wavelength resolution from 5 pm to 2 nm, allowing it to support a wide range of applications, from narrowband peak/notch measurements to wideband spectral measurements.

In the past, OSA users have struggled to maintain accuracy. Ambient temperature change, vibrations, and shock can all affect the measurement accuracy of OSAs. The AQ6380 makes this easier with on board calibration based on a built-in light source.

The AQ6380 will help development engineers improve the speed, bandwidth and quality of optical devices. Overall, this will increase the performance and sustainability of the next generation of telecommunication networks, while reducing their carbon footprint. The result will be a greener technology that can help transform all aspects of our lives.