Key Techniques For A Stabilized Laser System

It is highly possible that the optical clock replace the microwave clock because ofits higher accuracy and precision. The optical clock consists of ultra-stable laseroscillator, ion/atom trap system and femtosecond frequency Comb. The narrowline-width laser system as the local oscillator is the core of an optical clock.We lock a diode laser to a Fabry-Perot cavity using the Pound-Drever-Halltechnique. There are various perturbing effects to the whole laser system such asvibrations, temperature fluctuations, intra-cavity power fluctuations, noise of the PDHerror signal photo detector and thermal noise, etc. In this thesis, I will introduce thetemperature control system, laser power control system and PDH error signal photodetector system in detail.We use a digital control system for the temperature control. The standard deviationof the temperature of the vacuum chamber which houses the FP cavity reaches1.210-4℃. The line-width broadening due to this effect is estimated to be12mHz.We stabilize the laser power by means of controlling the Acoustic OpticalModulator driving power with a PID controller. The stabled laser power reaches a levelof0.01%at1Hz.At last, the thesis introduces the Photo-detector for the detection of PDH errorsignal, including the circuit schematic and the calculation of signal to noise ratio andnoise equivalent power. We test the homemade photo detector, and discuss the results.