Optical frequency combs have been developed increasingly for over 20 years since the first advent at the beginning 21 century. The original goal of inventing them is to solve the problem of measuring and counting the optical frequencies, which is very critical for applications in precision spectroscopy and optical atomic clocks. However, they never foresaw that the range of the applications can exceed metrology, spectroscopy, and clocks, and it has been extended to other important fields, such as attosecond generation, time and frequency transfer, synchronization, absolute distance measurement, and microwave photonics. Of course, more and more applications also facilitate the fast-evolving of the optical frequency comb (OFC) technology inversely. Apart from the traditional mode-locked femtosecond laser combs, new microresonator frequency combs and electro-optic frequency combs have been invented and achieved great success in principle, configuration, and applications as well over the last decade.
The stability, phase noise, spectrum range, and integration are the main features of OFCs. As for the stability, like traditional combs as Ti: sapphire, fiber, or all-solid-state mode-locked femtosecond lasers, has reached 10-20 levels which are the same as the best optical clock. However, for microresonator and EO combs, this is still one direction of their efforts even though they have advantages in size, structure, and power dissipation. Exploring large spectrum bandwidth and different ranges is always one aim of OFC technology, from XUV to mid-infrared, far-infrared, and even THz, so finding novel laser sources or using nonlinear frequency conversion techniques are very important. In addition, there is emerging a kind of requirement of applications in the field of outer space, for example, a long-distance time and frequency transfer from the earth to the satellite, where a robust, reliable, and high-integrated frequency comb should be required, then it is necessary to develop more integrated and portable OFC systems. Finally, it is well known that applications using OFCs technology are increasing significantly and demonstrating new peculiarity in the respective of combining the AI. This is undoubtedly to enhance the further development of the OFC technology.
The above trends in optical frequency combs present a lot of challenges and chances, that we are interested in. Therefore, we welcome researchers to contribute Original Research and Review papers for this Research Topic sharing the most recent ideas in the field of OFC sources, technology, and applications. Potential topics include, but are not limited to:
• Novel OFC laser sources
• Advanced coherent or adaptive control technology for OFC
• New mechanism or theory in OFC
• Fabrication and design for integrating on-chip micro and EO combs
• OFC applications in metrology and spectroscopy
• New applications using OFC technology
Optical frequency combs have been developed increasingly for over 20 years since the first advent at the beginning 21 century. The original goal of inventing them is to solve the problem of measuring and counting the optical frequencies, which is very critical for applications in precision spectroscopy and optical atomic clocks. However, they never foresaw that the range of the applications can exceed metrology, spectroscopy, and clocks, and it has been extended to other important fields, such as attosecond generation, time and frequency transfer, synchronization, absolute distance measurement, and microwave photonics. Of course, more and more applications also facilitate the fast-evolving of the optical frequency comb (OFC) technology inversely. Apart from the traditional mode-locked femtosecond laser combs, new microresonator frequency combs and electro-optic frequency combs have been invented and achieved great success in principle, configuration, and applications as well over the last decade.
The stability, phase noise, spectrum range, and integration are the main features of OFCs. As for the stability, like traditional combs as Ti: sapphire, fiber, or all-solid-state mode-locked femtosecond lasers, has reached 10-20 levels which are the same as the best optical clock. However, for microresonator and EO combs, this is still one direction of their efforts even though they have advantages in size, structure, and power dissipation. Exploring large spectrum bandwidth and different ranges is always one aim of OFC technology, from XUV to mid-infrared, far-infrared, and even THz, so finding novel laser sources or using nonlinear frequency conversion techniques are very important. In addition, there is emerging a kind of requirement of applications in the field of outer space, for example, a long-distance time and frequency transfer from the earth to the satellite, where a robust, reliable, and high-integrated frequency comb should be required, then it is necessary to develop more integrated and portable OFC systems. Finally, it is well known that applications using OFCs technology are increasing significantly and demonstrating new peculiarity in the respective of combining the AI. This is undoubtedly to enhance the further development of the OFC technology.
The above trends in optical frequency combs present a lot of challenges and chances, that we are interested in. Therefore, we welcome researchers to contribute Original Research and Review papers for this Research Topic sharing the most recent ideas in the field of OFC sources, technology, and applications. Potential topics include, but are not limited to:
• Novel OFC laser sources
• Advanced coherent or adaptive control technology for OFC
• New mechanism or theory in OFC
• Fabrication and design for integrating on-chip micro and EO combs
• OFC applications in metrology and spectroscopy
• New applications using OFC technology