Accurate Optical Frequency Measurement and Synthesis

In recent times a remarkable breakthrough has occurred in the field of optical frequency measurement and synthesis. For the first time it is now possible to generate arbitrary waveform light pulses, perform accurate optical frequency synthesis and accurately measure the frequency of optical frequency signals. These long dreamed of possibilities have been delivered because of the existence of two innovative technologies: ultrafast pulsed lasers that generate pulses only a few optical cycles in duration, and specially tailored optical fibre that can broaden the output spectrum of these light pulses across the entire optical spectrum. In a seemingly improbably feat, this combination of the extremely fast and extremely broad has proven to enable reliable measurements with a higher precision than any other technique. This article outlines the mechanisms inherent to the operation of the pulsed laser, as well as the tailored optical fibre, and then presents the techniques that enable the promised frequency synthesis and measurement.