Next-Generation Optical Frequency Combs and Their Photonic Applications

Dear Colleagues,

Imagine possessing a ruler so precise that it could measure the vast distance to the moon down to the width of a human hair, or a clock so accurate that it would lose less than a second over the entire age of the universe. This is not science fiction, but the remarkable reality enabled by Optical Frequency Combs (OFCs). These revolutionary devices act as ultra-stable rulers for light, generating a spectrum composed of millions of perfectly evenly spaced, discrete laser lines, like the teeth of an infinitely fine comb stretching across the optical spectrum. While traditional OFCs, recognized by the 2005 Nobel Prize in Physics, have already revolutionized precision measurement, a new wave of innovation is surging: next-generation Optical Frequency Combs. These advancements are not merely incremental improvements; they represent a paradigm shift, making these extraordinary tools smaller, more efficient, more versatile, and more accessible than ever before, poised to unlock unprecedented capabilities across science and technology.

OFCs bridge optical and microwave frequencies with perfectly spaced, phase-coherent spectral lines. While traditional mode-locked laser OFCs are mature, the field is now advancing toward next-generation architectures. These emerging combs offer significant reductions in size, weight, and power; enhanced robustness; lower noise; broader spectral coverage; higher conversion efficiency; and seamless integration with photonic integrated circuits (PICs).

Evolving OFC technology will enable next-generation combs to surpass traditional lasers in lab and field settings, driving breakthroughs across photonics. Key applications include setting new standards in ultra-stable optical atomic clocks and precision metrology; revolutionizing spectroscopy and sensing via dual-comb spectroscopy (DCS) for both lab analysis and open-path environmental monitoring; pioneering novel laser cooling/trapping methods; serving as fundamental tools in quantum information science for entanglement generation and manipulation with quantum frequency combs (QFCs); and unlocking new capabilities in hyperspectral imaging and multidimensional spectroscopy.

This Special Issue highlights next-generation OFC sources, technologies, and their groundbreaking applications. We invite submissions of theoretical, numerical, and experimental papers on topics including, but not limited to, the following:

• Novel sources and generation;
• Rapid, high-resolution spectroscopy;
• Ultra-precision metrology;
• Microwave generation;
• Hyperspectral imaging;
• Microresonator- and soliton-based combs;
• Chip-scale and integrated photonic frequency combs;
• Frequency comb stabilization and noise reduction;
• Dual-comb spectroscopy;
• Applications in optical communications.

Dr. Yichi Zhang
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photonics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• optical frequency combs
• soliton combs
• microcombs
• dual-comb spectroscopy
• quantum frequency combs
• EO comb
• kerr comb
• chip-scale frequency combs
• spectral shaping
• precision measurement
• precision metrology
• hyperspectral imaging
• microwave generation
• microresonators
• noise characterization
• integrated photonics