The evolving optical frequency comb [Invited]
In the past decade we have witnessed remarkable advances associated with the frequency stabilization of the comb present in the output of a mode-locked femtosecond laser. While proving itself to be fantastically successful in its role as the “gears” of optical atomic clocks, the optical frequency comb has further evolved into a valuable tool for a wide range of applications, including ultraviolet and infrared spectroscopy, frequency synthesis, optical and microwave waveform generation, astronomical spectrograph calibration, and attosecond pulse generation, to name a few. In this review, I will trace several of these developments while attempting to offer perspective on the challenges and opportunities for frequency combs that might lie ahead in the next decade.