Development Of698nm Narrow-linewidth Lasers

Narrow-linewidth lasers have a variety of important applications such as optical atomicclock, high-precision laser spectroscopy, measurements of fundamental physical constants.We have built an ultra-stable laser at the wavelength of698nm for Sr atomic optical clocks.In this work, the frequency of an ECDL laser is stabilized to a reference cavity with a finesse of~400,000by conventional PDH method. The mode-matching efficiency of the high-finessecavity is improved to above95%. By optimizing the signal-to-noise ratio of the error signal, werealized the frequency stabilization based on the reference cavity. Error analysis shows that thelinewidth of the laser is about10Hz.In the transmission of narrow-linewidth laser via optical fibers, the phase noise introducedby the environment, resulting in broadening of the laser linewidth. In this work，we establishedthe experimental system of the fiber phase noise suppression. Using this system, the linebroadening introduced by the20m optical fiber is reduced to1mHz, the precision of the opticalfrequency transfer is better than3×10-18.