Research On Laser Modulation And CPT Signal Demodulation In Chip-scale Atomic Clock

With the rapid development of electronic science and technology, Industries raiseincreasing requirements on the precision of atomic clocks. Today, most of studies onatomic clocks focus on two aspects. One is the accuracy and frequency stability of atomicclocks and the other is the miniaturization of atomic clocks. However, chip scale atomicclocks using CPT principle fulfill the requirements mentioned above and offer the betterportability.Based on the background, this thesis tends to develop a low-power, miniaturized CPTatomic clock, which is expected to play an important role in portable equipments andnavigation systems. The system consists of three parts, the physical package, the RFmodule and the peripheral control circuit module, which adopts a local oscillator to lockthe hyperfine level of cesium atoms and obtains high stable frequency standard.The hardware of this system includes the physical package, the PLL circuit, thesmall-signal amplifier, the signal acquisition circuit and the control circuit. The softwareincludes temperature compensation, signal modulation and demodulation, data processingand communications for control chips. The software platform is based on the developmentenvironment of MSP430IAR Embedded Workbench5.3Evaluation. Users cancommunicate with the host computer via JTAG microcontroller. In addition, the results ofreal-time data collected can be observed through the PC interface, so that the status of theatomic clock can be determined. In this thesis, the laser modulation and CPT demodulationmethods have been studied. The locked frequencies of the laser and microwave signal havebeen achieved through the modulation and demodulation.Finally, these methods are combined with temperature servo loop, PLL loop and aphysical package to form a prototype of chip scale atomic clock. The prototype is testedand the performance shows good results. The Allan Variance is better than5.356×10-11forone second and4×10-12for one hour, and the power consumption is less than200mW, which meets the design requirements of chip-scale atomic clocks.