BACKGROUND The generation and control of coherent electromagnetic waves, such as
those provided by electronic oscillators in the radio frequency domain or lasers in the optical …

Optical frequency combs were developed nearly two decades ago to support the world's
most precise atomic clocks. Acting as precision optical synthesizers, frequency combs …

Optical atomic clocks, use electronic energy levels to precisely keep track of time. A clock
based on nuclear energy levels promises a next-generation platform for precision metrology …

Dual-comb spectroscopy is an emerging new spectroscopic tool that exploits the frequency
resolution, frequency accuracy, broad bandwidth, and brightness of frequency combs for …

Two decades after its invention, the classic self-referenced frequency comb laser is an
unrivalled ruler for frequency, time and distance metrology owing to the rigid spacing of its …

Optical-frequency synthesizers, which generate frequency-stable light from a single
microwave-frequency reference, are revolutionizing ultrafast science and metrology, but …

We review the most recent progress in ultralow-noise mode-locked fiber lasers and fiber-
based frequency-comb sources. With the rapid progress in theory, measurement, and …

Mid-infrared dual-comb spectroscopy has the potential to supplant conventional Fourier-
transform spectroscopy in applications requiring high resolution, accuracy, signal-to-noise …

Deployed optical clocks will improve positioning for navigational autonomy, provide remote
time standards for geophysical monitoring and distributed coherent sensing, allow time …

Abstract Global Navigation Satellite Systems (GNSS) are enabled by atomic clocks, which
provide the timing precision and accuracy required for the ranging measurements …