Optimization of the atomic candle signal used for microwave power standard based on the Rabi frequency

A new microwave power standard using the Rabi frequency of gaseous atoms in a glass cell has been proposed. In this new power standard, the incident microwave power is determined by maximizing the amplitude of the atomic candle signal. Therefore, the line width and signal-to-noise ratio (SNR) of the atomic candle signal are the major parameters determining the measurement uncertainty. In this paper we describe the optimization of the atomic candle signal. Our results show that the accuracy of determination of the Rabi frequency can be improved more than twofold by regulating the intensity of the probing laser.