Analysis and design of a micromachined Rb-85 filter in passive rubidium atomic clock

In this paper we present an analysis and design of a micromachined Rb-85 filter for passive rubidium atomic clock. By introducing the Lorentzian shape functions into the derived output light intensity equation of the filter for a monochromatic light, a formula of light intensity in a filter with a light spectrum input is set up, and parameters in this formula involving transition coefficient, frequency shifts and linewidth are studied and determined. Based on these, a micromachined Rb-85 filter with high filtering performance is designed, in which more than 90% of a-line component in the light spectrum input from the Rb-87 lamp is filtered but b-line component is weakened by less than 3%.