Laser Stabilization

Over the past fty years, lasers have become one of the most valuable tools for studying physics. Monochromatic, phase coherent laser light can be used for experiments which were impractical or impossible with traditional light sources. Of course, since the laser’s invention, fundamental limitations on a laser’s freqency stability and phase coherence time have been recognized [1]. Yet, most lasers are limited by technical noise sources such as vibrations, temperature uctuations, and thermal noise of the resonator mirrors. This instability limits a laser’s usefullness for applications such as precision spectroscopy, measurements of physical constants, and atomic clocks. For this reason, signi cant research continues in the eld of laser stabilization. The Ye goup at JILA is currently endeavoring to achieve a laser with linewidth below .5 hertz. This result will match the best laser stability ever recorded and increase the precision of the group’s strontium atomic clock. In this paper, I will report on this experiment and the progress made during a ten week period with the group. Furthermore, this paper will serve as a brief introduction to the Pound-Drever-Hall method of laser stabilization which is commonly used in ultra-stable laser systems.