Research On The Schemes On The Chip-scale Atomic Clock And The Pocket Ramsey-CPT Atomic Clock

Coherent Population Trapping(CPT)atomic clock utilizing dichromatic light to interact with atoms to generate CPT signal,which is used as microwave frequency discriminating signal,so that which is the microwave clock without a microwave cavity.Without the microwave cavity,it is easy to realize the small size low power consumption atomic clock,which make CPT atomic clock the application competitive atomic clock.At the present,pocket and chip scale CPT atomic clocks have entered the application market,and are getting more and more widely used.Our group has been studying the CPT atomic clock for a long time and achieved certain valuable study results,and has realized pocket and chip scale CPT atomic clocks.The author of this thesis has studied CPT atomic clocks with the group,aimed at enhancing the application competitiveness of CPT atomic clock,the author has been concentrated on improve the output frequency performances of the pocket and chip scale CPT atomic clocks,the main achieved study results are:(1)The CPT atomic clock using left and right circularly polarized lights interference enhancement CPT resonance.The scheme for the present CPT atomic clock products utilize the single(left or right)circularly polarized light to generate CPT resonance with atoms,which causes that certain atoms are pumped to the spin polarization dark state and the atoms have no contribution to the CPT resonance,so that it reducing the effective working atoms.However,left and right circularly polarized lights simultaneously interacting with atoms causes quantum interference which relates to efficiency of CPT resonance.We design a scheme that properly arranges the optical path difference between left and right circularly polarized lights to realize the ideal phase difference between their generated CPT resonances.By this way,the interference enhancement CPT signal can be achieved for CPT atomic clock.We have experimentally studied the scheme and with the realized atomic clock we measured the short term frequency stability and proofed that it got about 3 times improvement.The studied scheme is suitable for implementing the chip scale CPT atomic clock.(2)The Ramsey-CPT atomic clock realized by switching laser diode driving current.CPT resonance combined with Ramsey interference will generate narrow linewidth Ramsey-CPT spectral line,and the atomic clock with better frequency stability can be achieved by utilizing the narrower linewidth Ramsey-CPT spectral line as the microwave frequency discrimination signal instead of the CPT spectral line.In general,large space size is needed for generating Ramsey interference which leads to oversize and make it difficult to realize application competitive atomic clock.Our team has developed a Ramsey-CPT atomic clock scheme realized by switching the microwave power which modulates the laser,and based on that we designed and studied a Ramsey-CPT atomic clock scheme realized by switching the driving current intensity which drives the laser diode.Our study result reveals that comparing the noise in Ramsey-CPT signal generated by microwave power switching process,the noise generated by the current intensity switching process is clearly weaker,thus better quality Ramsey-CPT signal can be achieved by the studies scheme.This studied scheme is also suitable for implementing the pocket Ramsey-CPT and chip scale CPT atomic clock.