Pushing boundaries with optical frequency combs (Invited Paper)

Optical frequency combs revolutionized precision measurements and metrology over 25 years ago. Initially they were used to measure optical frequencies at hundreds of Terahertz in fundamental physics experiments, and to calibrate laser frequencies for interferometric distance measurements. Many more applications have emerged over the years. Advances in the accuracy, wavelength coverage, and ease-of-use of frequency combs have made them an essential tool in research labs and industry. In this talk we will introduce the concept of the frequency comb, and highlight some examples of applications that rely on them. We will also provide insights into new developments of compact, integration-ready frequency combs. Optical clocks require frequency combs as clockworks to operate with 18 digits of precision. Quantum computers based on cold atoms or trapped ions use lasers down to the Hertz-linewidth-level to address specific atomic transitions and write and manipulate Qubits. Such lasers can be conveniently realized via stabilization to a frequency comb. New generations of GNSS will use optical clocks, so frequency combs are being manufactured to be space-ready and autonomous, in particular for installation on the Bartolomeo platform on the International Space Station as part of the COMPASSO project.