Laser phase fluctuations in a four-level atomic system in N-configuration
Homi Bhabha National Institute, Bhabha Atomic Research Centre,
2 Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, 400 085 Mumbai, India
Received: 3 January 2013
Published online: 4 June 2013
We discuss here the effect of laser phase fluctuations on coherent spectroscopy of four-level N-system interacting with a trichromatic radiation field of frequencies Ωi, (i = 1−3). The laser phase variables are described by the Wiener-Levy diffusion process to specify the bandwidths (Γi) and cross-correlations (Γij) that may exist between pairs of laser fields. A general formalism based on the master equation and theory of multiplicative stochastic processes is developed and used to study three-photon and (2+1)-photon absorptive resonances in model N-system of 40Ca+ ion. It is observed that the resonances are suppressed or broadened by all Γi,(i = 1−3), while their revival is dependent only on Γ12 and Γ23, and yet the revival is only partial even when the relevant fields are critically correlated. In contrast Γ13 is observed to deteriorate the absorptive resonances. The distinctive features of the steady state and time dependent behavior of the system under three-photon and (2 + 1)-photon resonance conditions and for fluctuating fields are discussed.
Key words: Quantum Optics
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2013