New tunable filter to provide high speed internet

New tunable filter to provide high speed internet

The path towards a faster internet has been hindered by energy consumption and cost per optical component.

Scientists have developed a new filter with the widest tuning span ever demonstrated on a silicon chip that could help provide the low-cost flexibility needed for next generation of high-speed optical networks.

The path towards a faster internet has been hindered by energy consumption and cost per optical component, said Wei Shi, Assistant Professor from Universite Laval in Canada.

Researchers have designed a tunable filter – an important component of high-capacity optical networks – that should save both money and energy because it can be readily integrated onto a photonic chip. The filter’s tuning span, which is a measure of how well the device can adjust to fluctuating data demands, is the widest ever demonstrated on a silicon chip.

The device has an unlimited free-spectral range, meaning it can operate over any range of frequencies. “The most exciting aspect is that these record-breaking results were achieved on the silicon photonic platform,” Shi said. “This indicates that the filter can be readily integrated with other well developed components for a novel integrated system,” said Shi.


The next-generation of internet technology could mean videos that stream in 3D or 360 degrees and vast amounts of cheap cloud data storage. As internet traffic has increased dramatically, bandwidth has become more precious, researchers said.

To maximise the power and cost efficiency, optical networks must be able to flexibly allocate bandwidth, giving each customer only what they need at any given time.

Flexible networks require tunable filters. Filters isolate a specific communication channel from all the others. Tunable filters give a network controller the freedom to select the frequency and bandwidth for each channel and change them on the fly.

The tunable filter that the researchers designed and tested has a tuning span of 670 GHz, much greater than the approximately 100 GHz span of current silicon-based filters. The researchers believe that with further modification their device’s tuning span can be further extended, to 1 THz.

The device works by using periodic nanostructures, 10,000 times smaller than the width of a human hair, to separate the different frequencies of light from each other.

The filter tuning is achieved with micro-heaters in the silicon chip that control the local temperature, which in turns affects the nanostructures and the frequencies they separate. The wide tuning span means the filter can handle a very large data volume carried by a single carrier, and can be rapidly adapted to dynamic changes in customer needs.