Frequency Comb Research Advances Using Tunable Diode Lasers

By New Focus, Inc.

The discovery of the optical frequency comb and the breakthrough work of Hänsch and Hall in refining the frequency comb technique have revolutionized the field of scientific metrology. Optical frequency combs now allow for a more precise measurement of frequencies in the optical domain (≈400-800 THz) by permitting for direct, phasecoherent
comparison to electronically manageable microwave and radio frequencies (≈3 Hz-300 GHz). The optical frequency comb is also poised to profoundly impact the precise measurement of time as it represents the long sought-after clockwork needed for the all optical atomic clock.

Beyond applications in precise frequency and time measurement, frequency combs are also finding application as versatile tools in molecular spectroscopy owing to their high spectral resolution, phase coherence among the comb lines, and broad spectral coverage. In this application note, we will look more closely at how the so-called “microcombs” are generated and what the role of external cavity diode lasers (ECDLs), such as the New Focus' Velocity laser, is in the microcomb generation process. We will briefly discuss how the microcomb is evolving into a compact, versatile tool with increasing application, for example, in the field of molecular spectroscopy. Although still maturing, the field of microcombshas the potential to transform various other disciplines, leading to compact comb generation platforms with numerous applications.