text: **The Linewidth of Ramsey Laser with Bad Cavity**
  
  Yang Li, Wei Zhuang, Jinbiao Chen,∗ and Hong Guo† 
  *CREAM Group, State Key Laboratory of Advanced Optical Communication*
  *Systems and Networks (Peking University) and Institute of Quantum Electronics,*
  *School of Electronics Engineering and Computer Science,*
  *and Center for Computational Science and Engineering (CCSE), Peking University, Beijing 100871, P. R. China*
  (Dated: October 29, 2018) 
  
  We investigate a new laser scheme by using Ramsey separated-ﬁeld technique with bad cavity. By studying 
  the linewidth of the stimulated-emission spectrum of this kind of laser inside the cavity, we ﬁnd its linewidth 
  is more than two orders of magnitude narrower than atomic natural linewidth, and it is far superior to that 
  of conventional optical Ramsey method and any other available subnatural linewidth spectroscopy at present. 
  Since any cavity related noise is reduced to cavity-pulling eﬀect in bad cavity laser, this Ramsey laser provides 
  the possibility of precision subnatural linewidth spectroscopy, which is critical for the next generation of optical 
  clock and atom interferometers. 
  
  PACS numbers: 42.55.Ah, 42.50.Ar, 42.60.Da, 32.30.-r 