What is optical communication?
Optical communication involves transporting data using light.
The Internet works by sending data via infrared light pulses that run through optical fibres. The optical fibres are installed in cables and act as waveguides to ensure that we can send data around the world. The waveguides are as thin as a human hair and are made of glass, plastic or another non-electrical material.
Fibreoptic cables have been shown to be far more efficient at transmitting data than cables that send electrical signals via copper. With light, you can send data faster and over longer distances, and the light signals are less receptive to noise.
Why is optical communication important?
Our need to send information through the Internet is steadily increasing. So much so that we constantly need to find new methods in the field of optical communication so we can send as much data as possible with the least possible use of energy.
The Internet currently consumes about 9% of the world’s total electricity consumption and about 2% of man-made carbon emissions. It requires a lot of energy to operate the large data centres, which need thousands of lasers to connect them optically, both internally and with the outside world.
Already within the next decade, the need for data capacity and bandwidth will increase dramatically as a result of all the things society is constantly connecting to the Internet. There is therefore a need to find methods to accelerate the development of energy-efficient technology that can make the Internet more environmentally friendly. And this is where research into optical communication comes into play.
Research into this key technology could contribute to creating a greener Internet, better microchips, energy-efficient data centres, etc. But even though the Internet uses energy, it also helps to save energy consumption in our society, because it helps make society more efficient. In this way, the Internet itself is part of the climate solution.
For example, for every kg of CO2 produced by using the Internet, it is already possible to save 1.5 kg of CO2 elsewhere in society due to smart digital solutions. And if we simultaneously make our communication technology more efficient, this saving is expected to grow from 1.5 up to as much as 10.
The World Economic Forum (WEF) estimates that digital technologies can reduce global carbon emissions by 15% in a number of sectors: transport, agriculture, construction, energy and manufacturing.
Read the WEF’s article Digital technology can cut global emissions by 15%. Here’s how
The International Energy Agency (IEA) also points out that digitalization is crucial to achieving sustainable societies based on smart cities, transport, buildings, lighting and communication. Read Digitalization and Energy.
However, the potential energy savings depend on how quickly we can maximize the energy efficiency of the communication infrastructure.
To reap the expected energy savings, communication networks must have ample capacity to support new smart initiatives. Time-critical services such as smart transport must be reliable, secure and increasingly energy efficient. This will enable a greener society and support the UN goals for sustainable development.
But time is short because there are technological challenges that need to be overcome.
One of them is defined as ‘Moore's Law’, which states that microchips have become smaller, faster and more energy efficient over the past 50 years.
However, Moore’s Law is stagnating as we are reaching the physical limit to how small a microchip can be. And that is now slowing down the pace of chip technology advances.
Today, microchips are produced using a technology in which the smallest parts measure as little as five nanometres.
Read the article Digitalization is an important climate tool.
How advanced is Denmark in the field of optical communication?
Denmark is one of the world’s leaders when it comes to research and development in optical communication.
DTU, for example, operates the research centre SPOC (Silicon Photonics for Optical Communications), where researchers carried out a groundbreaking experiment in 2012.
They tested a method of optimizing the Internet so that it can transmit even more data while saving energy. They did this by using a single powerful laser chip instead of the thousands of lasers used today to transmit more than 600 terabytes of data per second through an optimized fibre. This corresponds to twice the total global Internet traffic, transmitted through one glass fibre.
The result illustrates the potential of optical communication and shows that much larger amounts of data can be transmitted than today without the use of thousands of lasers that consume large amounts of energy.
Therefore, the researchers are working to make the solution a reality in a research project, INCOM, which has received DKK 60 million in funding from Innovation Fund Denmark and is being carried out in collaboration with the University of Aarhus and 12 companies.
Light is also far better than electronics at transmitting data, so every time the optical fibres have to communicate with ordinary electronic circuits, the speed drops significantly and energy is used. Therefore, the researchers are also working on developing an optical chip which will make it possible to receive Internet signals much faster.
The researchers are also working on designing so-called chip-based frequency combs, partly in a major EU project supported by Horizon 2020.
A frequency comb is a method that can create very short light pulses using one laser. This method will make it possible to increase the capacity of a communications network that handles data traffic at speeds of over 100 terabytes per second.
A frequency comb will enable researchers to replace thousands of standard lasers with just a single one, which will save huge amounts of energy.
What are the future perspectives?
The Internet has the potential to transport far more data with minimal use of energy. But greater efforts must be made to put the solutions into practice, as Internet traffic is expected to increase by 30% a year in future. Conversely, smart digital solutions will help save energy. That is why the Internet is also part of the solution to the climate crisis.
The next generations of optical communication systems will be so complex that machine learning will be the quickest way to find solutions that can transport huge amounts of data in the most energy-efficient way. Therefore, researchers are working on how to integrate machine learning into research in the field of optical communication.
The advantage of machine learning is that the computer is able to analyse huge amounts of data and find algorithms and connections without being pre-programmed.
For example, researchers can use machine learning to identify models that can describe the relationship between transmitter and receiver when we develop lasers, frequency combs, networks, etc. to transport large amounts of data.
There are many factors, such as bandwidth, channel effects, frequency noise and traffic routes, that can play a role in the search for the most energy-efficient solution.
The increasing focus on quantum technology to improve Internet security makes the task of designing optical communication solutions even more challenging because it requires coexistence and control of classic channels and quantum channels in the same optical network. This creates a need to develop intelligent optical receivers that can distinguish between classical signals and quantum signals so here too it is necessary to use machine learning and artificial intelligence in the development process.