The Research On The Frequency Stabilization Of The Ti:Sapphire Laser For The⁴⁰Ca⁺Ion Optical Frequency Standard

Laser is one of the most important inventions in the20th century. Because of its excellent coherence in the time and space domain, it is widely used in the collimation, ranging, measuring system, integrated circuit, optical fiber communications, industrial manufacture, military fields and so on. Although lasers have better coherence than the common light, their linewidths are limited by the influence of the environment and their own instability. The lasers with high stability are required on the research of the precise spectroscopy. On the other hand, lasers which have narrow linewidths can be used as the local oscillators for the optical frequency standards. By locking a laser to the spectral transition of the atom, an optical frequency standard is realized. As the invention of the femtosecond optical frequency comb, the develop pment of the laser cooling and the ion trap, optical frequency standards are being developed in many laboratories around the world. Because of the higher frequency compare to the microwave, optical frequency standards can achieve higher accuracy and stability. For the40Ca+ion optical frequency standard which is being developed in our laboratory, we use the Paul ion trap to confine one40Ca+ion. The natural linewidth of the clock transition is about0.16Hz and its Q factor is at1015level. At the same time, the overall systematic uncertainty of the clock resonance is6.5×10-16. We use a Ti:sapphire laser to detect the clock transition. We achieved a laser linewidth of～3Hz by locking the laser to a stable Fabry-Perot cavity using the Pound-Drever-Hall scheme. This thesis summarizes the works during my Master’s study period, and the structure is organized as following.1. A new ULE reference cavity was installed in a vacuum system. Then the finesse of the cavity was measured. We also measured the sensibility of the vibration of the platform.2. We optimized the setup of the optical path and the locking electronics. At the same time, the noise level, the vibration of the platform and the temperature of the reference cavity were well controlled. We achieved a laser linewidth which was-3Hz, and the Allan deviation was better than1×10-14(1-10s) by observing the beat note of the two reference cavities.3. Four signal generators with a bandwidth of80MHz and2photodiode amplifier circuits with a bandwidth of160MHz were made. In addition, we accomplished the fiber noise cancellation experiment and achieved a linewidth which was less than20Hz by detecting the spectral resonance lines of the40Ca+ion.