New on-chip frequency comb is 100x extra environment friendly

(Nanowerk Information) On-chip laser frequency combs — lasers that emit a number of frequencies or colours of sunshine concurrently separated just like the tooth on a comb — are a promising expertise for a spread of functions together with environmental monitoring, optical computing, astronomy, and metrology. Nevertheless, on-chip frequency combs are nonetheless restricted by one significant issue — they aren’t at all times environment friendly. There are a number of methods to mitigate the effectivity downside, however all of them endure from trade-offs. For instance, combs can both have excessive effectivity or broad bandwidth however not each. The shortcoming to design an on-chip laser frequency comb that’s each environment friendly and broad has stymied researchers for years and hindered the widespread commercialization of those gadgets. Now, a group from the Harvard John A. Paulson College of Engineering and Utilized Sciences (SEAS) has developed an electro-optic frequency comb that’s 100-times extra environment friendly and has greater than twice the bandwidth of earlier state-of-the-art variations. “Our system paves the best way for sensible optical frequency comb mills and opens the door for brand spanking new functions, mentioned Marko Lončar, the Tiantsai Lin Professor of Electrical Engineering at SEAS and senior creator of the examine.“It additionally offers a platform to analyze new areas of optical physics.” The analysis is printed in Nature Photonics (“Excessive-efficiency and broadband on-chip electro-optic frequency comb mills”). A brand new on-chip frequency comb combines a coupled resonator with an electro-optical frequency comb to enhance the effectivity of frequency combs and enhance the bandwidth. (Picture: Yiqing Pei, Harvard SEAS) This development builds upon earlier analysis from Lončar and his group. In 2019, Lončar and his lab demonstrated the primary secure, on-chip frequency comb that may very well be managed with microwaves. This so-called electro-optical frequency comb, constructed on the lithium niobate platform pioneered by Lončar’s lab, spanned your complete telecommunications bandwidthbut was restricted in its effectivity. In 2021, the group developed a coupled resonators system to manage the circulation of sunshine, and used them to exhibit on-chip frequency shifters – a tool that may change the colour of sunshine with almost 100% effectivity. The newest analysis applies the 2 ideas to deal with the problem in resonator primarily based electro-optic frequency combs – efficiency-bandwidth tradeoff. “We demonstrated that by combining these two approaches — the coupled resonator with the electro-optical frequency comb — we may enhance the effectivity lots with out sacrificing bandwidth. In actual fact, we really improved bandwidth,” mentioned Yaowen Hu, a analysis assistant at SEAS and first creator of the paper. “We discovered that once you enhance the efficiency of the comb supply to this degree, the system begins working in a completely new regime that mixes the method of electro-optic frequency comb era with the extra conventional strategy of a Kerr frequency comb,” mentioned Mengjie Yu, a former postdoctoral fellow at SEAS and co-first creator of the paper. Yu is presently an Assistant Professor on the College of Southern California. This new comb can generate ultrafast femtosecond pulses at excessive energy. Along with the high-efficiency and broadband, this system will be helpful for functions in astronomy, optical computing, ranging and optical metrology.