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Ultra-Low Phase Noise Atomic Frequency References (Clocks) Using Coherent Population Trapping In Rubidium Vapour

The aim of this project is to design ultra-stable atomic frequency references (clocks) with improved phase noise and stability characteristics compared to the currently available configurations. The system incorporates a physics package based on Coherent Population Trapping (CPT) in Rubidium (Rb) or Caesium (Cs) vapour for long term satability. A frequency synthesis chain consisting of Ultra-low phase noise Crystal Oscillators (XO) and Dielectric Resonator Oscillators (DRO) is used to achieve a good short term stability and excellent phase noise. 

Low Phase noise oscillator block diagram

Block diagram of the complete system. The orange block represents the physics package, the blue block shows the laser centre frequency stabilization loop and the green block shows the frequency synthesis chain.


CPT Physics Package photo



  • Start: September 2015