Research Of The Relevant Electronic System Of CPT ～(87)Rb-maser Atomic Clock In Space

Due to their line-widths, low power consumption and robustness, coherent population trapping (CPT) resonances have been under consideration as frequency references for many years. The institution electronics national in Italy and national institute of standards and technology in USA etc have carried out experiment in frequency standard field based on the coherent population trapping. Based on the advantages of CPT and the progress in frequency standards, CPT maser vapor cell frequency standard will be a candidate for satellite space-positioning. In this paper we will discuss the design and test of electronic systems in CPT maser for satellite, focusing on the design and parameters of microwave cavity, the stabilization electronics of external cavity diode laser and Low noise multiplier based on PLL.In the research of CPT-maser Atomic clock for satellite, we designed columned microwave cavity working at the mode of TE011, which depending on actual requirement. Then we measured its performance parameter including syntonic frequency and Q value etc. As the result shown, its frequency-cavity length relation is identical with the calculated result. And its Q value is among 2500 to 3200, which is up to requirement of the experiments but still have a great space to improve. External cavity laser diode is very important to the CPT frequency standard, stable frequency of which is the basic of getting CPT maser. For one hand, we designed Precise Temperature Controlling circuit to reduce the effect of temperature variance. This system could limit the variance in the range of±0.01℃. For another hand, we designed a system based on Lock-in principle to stabilize frequency output of the laser. Frequency multiplier is an important part of frequency chain of CPT clock. Its noise level has a relatively large influence on performance of the CPT clock. We analysis the noise of each part of Phase Locked Loop, and adopted some method to optimize the noise, completed the low noise PLL frequency multiplier from 10MHz to 100MHz, got a more stable frequency output.At present, domestic research institutes focus on the research of traditional Atom clock, some of which have launched studies on Passive CPT Atomic clock, funded by related departments. However, research on Atom clock which is based on CPT-maser principle has not been involved yet. As an import part of"Experimental device of new generation CPT-maser Atom clock for satellite", working mentioned in present paper have made great improvement and laid the theoretical and experimental groundwork for the development of CPT maser atom clock project sample for satellite.