On-chip, electronically tunable frequency comb

1 min read

An integrated, on-chip frequency comb that is efficient, stable and highly controllable with microwaves has been developed by researchers from the Havard John A. Paulson School of Engineering and Applies Sciences (SEAS) and Stanford University.​​

"In optical communications, if you want to send more information through a small, fibre optic cable, you need to have different colours of light that can be controlled independently," said Marko Loncar, the Tiantsai Lin Professor of Electrical Engineering at SEAS. "That means you either need a hundred separate lasers or one frequency comb. We have developed a frequency comb that is an elegant, energy-efficient and integrated way to solve this problem."

Prof Loncar and his team developed the frequency comb using lithium niobite, a material well-known for its electro-optic properties, meaning it can efficiently convert electronic signals into optical signals. Thanks to the strong electro-optical properties of lithium niobite, the team's frequency comb spans the entire telecommunications bandwidth and has dramatically improved tunability.

This was accomplished using microwave signals, allowing the properties of the comb – including the bandwidth, the spacing between the teeth, the height of lines and which frequencies are on and off – to be tuned independently.

These compact frequency combs show promise for optical communication in data centres and cloud computing.

"A frequency comb, by providing many different colours of light, can enable many computers to be interconnected and exchange massive amounts of data," added Joseph Kahn, Professor of Electrical Engineering at Stanford.