Complete wavelength mismatching effect in a Doppler broadened Y-type six-level EIT atomic medium

We present a theoretical study of the Doppler broadened Y-type six-level atomic system, using a density matrix approach, to investigate the effect of varying control field wavelengths and closely spaced hyperfine levels in the 5P(3/2) state of Rb-87. The closely spaced hyperfine levels in our six-level system affect the optical properties of Y-type system and cause asymmetry in absorption profiles. Depending upon the choices of pi-probe, sigma(+) -control and sigma(-) -control fields transitions, we consider three regimes: (i) perfect wavelength matching regime (lambda p = lambda(c1) = lambda(c2)) , (ii) partial wavelength mismatching regime (lambda(p) not equal lambda(c1) = lambda(c2)), and (iii) complete wavelength mismatching regime (lambda(p) not equal lambda(c1) not equal lambda(c2)). The complete wavelength mismatching regime is further distinguished into two situations, i.e., lambda(c1) < lambda(c2) and lambda(c1) > lambda(c2). We have shown that in the room temperature atomic vapor, the asymmetric transparency window gets broadened in the partial wavelength mismatching regime as compared to the perfect wavelength matching regime. This broad transparency window also splits at the line center in the complete wavelength mismatching regime. (C) 2014 Elsevier B.V. All rights reserved.