Optical frequency combs convert a laser source containing a single frequency of light into pulses that include thousands of frequencies. This project aims to develop the technology for a growing list of applications. Using a comb working at optical telecommunications wavelengths, project physicists have transmitted signals from next-generation optical atomic clocks across hundreds of kilometers. They have demonstrated how pairs of combs can increase by a factor of one hundred the speed of infrared spectroscopy for chemical analysis, while also enhancing sensitivity. Frequency combs also promise to provide extremely accurate distance measurements and to assess the quality of high-speed telecommunications signals with unprecedented precision.