助攻計畫-為太空光梳光鐘用之量子控制光梳光譜(2/3)

Optical frequency comb lasers have recently been regarded as very important lasers in the field of space metrology because they have high peak power and travel farther than continuous wave lasers without losing too much of its intensity, so they are suitable for optical phase-locking between satellites; and because comb lasers repetition rate are within the microwave frequency band, the frequency can be calibrated by the ground-level primary time standard . Compared with the optical frequency, microwave is less affected by atmospheric scattering. Therefore, Comb laser has recently become the first choice for time-keeper instruments on satellites, especially when there are a large number of low-orbit satellites that need to be synchronized, and in the 6G era dominated by satellites in the future, precise control of the timing of large amounts of data transmission will be a key technology. So far, there is only a record of an optical comb laser being successfully sent to a rocket, and there is no record on a satellite. In the past two years, the UCLA and NIST teams in the United States have devoted themselves to the development of micro-disk comb laser clocks (micro-disk comb), and the Max Planck Institute for Quantum Optics in Germany has tested fiber optic comb optical clocks from rockets. But no matter what they do, the basic problem is not solved, that is, they all need a cesium atomic clock or rubidium optical clock to lock their laser repetition rate, this clock cannot be scaled down any more and is not easy to operate. The fundamental solution to this problem is to directly frequency-lock the optical comb laser to the atomic transition recommended by the International Bureau of Weights and Measures (http://www.bipm.org/en/publications/mises-en-pratique/standard- frequencies.html)