text: In summary, we propose a new subnatural 
  linewidth spectroscopy technique, which is a laser by us- 
  ing Ramsey seperated-ﬁeld cavity to realize the output of 
  stimulated-emission radiation via multiple coherent interac- 
  tion with atomic beam. We ﬁnd the linewidth of Ramsey laser 
  is subnatural if we choose an appropriate atomic level, and the 
  bad-cavity laser mechanism will dramatically reduce cavity- 
  related noise as discussed in active optical clock [15–19]. Our 
  results show that this new subnatural linewidth spectroscopy 
  is superior to conventional optical Ramsey seperated-ﬁeld 
  spectroscopy and any other available subnatural spectroscopy 
  technique at present [3–10]. Considering one have to ap- 
  ply the separated-ﬁeld method in any phase detection as in 
  Ramsey-Bord*e*´interferometer [2], to investigate the eﬀects of 
  phase diﬀerences between the two oscillating ﬁelds [31] in 
  this stimulated separated-ﬁeld method with such subnatural 
  linewidth will be our next research aim. 
  
  *Conclusion:*
  
  [18] Y. Wang, Chinese Science Bulletin**54**, 347 (2009). 
  [19] D. Meiser, J. Ye, D. R. Carlson, and M. J. Holland, Phys. Rev. 