New On-Chip Frequency Comb is 100x More Efficient

An electro-optic frequency comb.

Device opens the door to applications in optical communications, sensing, and the search for exoplanets. (Image: via Pixabay)

On-chip laser frequency combs — lasers that emit multiple frequencies or colors of light simultaneously separated like the tooth on a comb — are a promising technology for a range of applications including environmental monitoring, optical computing, astronomy, and metrology. However, these are still limited by one serious problem — they are not always efficient. There are several ways to mitigate the efficiency problem, but they all suffer from trade-offs.

A new on-chip frequency comb combines a coupled resonator with an electro-optical frequency comb to improve its efficiency and bandwidth.
A new on-chip frequency comb combines a coupled resonator with an electro-optical frequency comb to improve its efficiency and bandwidth. (Image: Yiqing Pei via Harvard SEAS)

An electro-optic frequency comb that is 100-times more efficient

For example, combs can either have high efficiency or broad bandwidth, but not both. The inability to design an on-chip laser frequency comb that is both efficient and broad has stymied researchers for years and hindered the widespread commercialization of these devices. Now, a team from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has developed an electro-optic frequency comb that is 100-times more efficient and has more than twice the bandwidth of previous state-of-the-art versions. Marko Lončar, the Tiantsai Lin Professor of Electrical Engineering at SEAS and senior author of the study said:

Subscribe to our Newsletter!

Receive selected content straight into your inbox.

“Our device paves the way for practical optical frequency comb generators and opens the door for new applications. It also provides a platform to investigate new areas of optical physics.”

The research is published in Nature Photonics. This advancement builds upon previous research from Lončar and his team. In 2019, Lončar and his lab demonstrated the first stable, on-chip frequency comb that could be controlled with microwaves. This so-called electro-optical frequency comb, built on the lithium niobate platform pioneered by Lončar’s lab, spanned the entire telecommunications bandwidth, but was limited in its efficiency.  In 2021, the team developed a coupled resonators device to control the flow of light, and used them to demonstrate on-chip frequency shifters — a device that can change the color of light with nearly 100 percent efficiency. The latest research applies the two concepts to address the challenge in resonator-based electro-optic frequency combs — efficiency-bandwidth tradeoff. Yaowen Hu, a research assistant at SEAS and the first author of the paper, said:

“We demonstrated that by combining these two approaches — the coupled resonator with the electro-optical frequency comb — we could improve the efficiency a lot without sacrificing bandwidth. In fact, we actually improved bandwidth.”

Mengjie Yu, a former postdoctoral fellow at SEAS and co-first author of the paper said:

“We found that when you improve the performance of the comb source to this level, the device starts operating in an entirely new regime that combines the process of electro-optic frequency comb generation with the more traditional approach of a Kerr frequency comb.”

Yu is currently an Assistant Professor at the University of Southern California. This new comb can generate ultrafast femtosecond pulses at high power. Together with the high efficiency and broadband, this device can be useful for applications in astronomy, optical computing, ranging, and optical metrology. 

Provided by Leah BurrowsHarvard John A. Paulson School of Engineering and Applied Sciences [Note: Materials may be edited for content and length.]

Follow us on TwitterFacebook, or Pinterest

Recommended Stories

Statue of Chinese alchemist and explorer Xu Fu in Wakayama, Japan.

3 Famous Chinese People Enshrined in Japanese Shrines

Traditionally, Japanese people have great respect for those who are capable or have made outstanding ...

Productivity going up.

Stop Wasting Your Time and Start Doing This

The way you use your time has a significant influence on your capacity to achieve, ...

Pink lotus flower in bloom with planet Earth and flower of life illustration along with fractals and nebulae drawings.

Ancient Chinese Mathematicians With the Power of Divination – Part 1 

There are many mystical and even magical aspects of ancient Chinese mathematicians. Anecdotes of them ...

Wooden emas at a Japanese shrine.

Japanese Shrines Vandalized by Pro-China Forces

In many Shinto and Buddhist shrines, you’ll find racks of emas — small wooden boards ...

Continous-wave lasing.

Continuous-Wave Lasing of Deep-Ultraviolet Laser Diode

A research group led by 2014 Nobel laureate Hiroshi Amano at Nagoya University’s Institute of ...

A cutting laser.

Gamma-Ray Laser Moves a Step Closer to Reality

A physicist at the University of California, Riverside, has performed calculations showing hollow spherical bubbles ...

A sunset with clouds.

The 8 Divinations and Wisdom of Life in Zhouyi

Zhouyi, which is believed to be the oldest text and is named after the Zhou ...

Allosaurus jimmadseni.

New Species of Allosaurus Discovered in Utah

A remarkable new species of meat-eating dinosaur has been unveiled at the Natural History Museum ...

A herbal apothecary.

A Famous Medicinal Herb Merchant in Chang’an During the Tang Dynasty

In the mid-period of the Tang Dynasty, there was a herb merchant named Song Qing ...

Send this to a friend