The optical properties of a four-level atomic system via coherent and incoherent pumping fields are investigated. The giant Kerr nonlinearity with reduced linear and nonlinear absorption, which has a major role in decreasing the threshold of optical bistability (OB), can be obtained with subluminal light propagation via adjusting the intensities of coupling fields. An incoherent pumping field is noticed to be an extra parameter to reduce the threshold of OB and multistability, and it can be used as an effective parameter in producing lasing with or without population inversion. In this model, optical multistability is achieved simply by tuning the intensity of coupling laser fields. Furthermore, it is shown that the subluminal and the superluminal light propagation can be obtained by appropriate values of the incoherent pumping rate.
© 2013 Optical Society of America
Original Manuscript: June 21, 2012
Revised Manuscript: August 6, 2012
Manuscript Accepted: August 31, 2012
Published: February 18, 2013
Tayebe Naseri, Seyyed Hossein Asadpour, and Rasoul Sadighi-Bonabi, "Some optical properties of four-level media via coherent and incoherent pumping fields," J. Opt. Soc. Am. B 30, 641-648 (2013)