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 …

A laser frequency comb is a broad spectrum composed of equidistant narrow lines. Initially
invented for frequency metrology, such combs enable new approaches to spectroscopy over …

The quest towards the integration of ultra-fast, high-precision optical clocks is reflected in the
large number of high-impact papers on the topic published in the last few years. This interest …

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

Terahertz (THz) science and technology have greatly progressed over the past two decades
to a point where the THz region of the electromagnetic spectrum is now a mature research …

Abstract 2D transition metal carbides, nitrides, and carbonitides called MXenes have
attracted much attention due to their outstanding properties. However, MXene's potential in …

On-chip optical resonators have the promise of revolutionizing numerous fields, including
metrology and sensing; however, their optical losses have always lagged behind those of …

We demonstrate broadband frequency comb generation in the mid-infrared (MIR) from 2.3 to
3.5 μm in a Si_3N_4 microresonator. We engineer the dispersion of the structure in the MIR …

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 …