Proper considerations of spatial profiles of the pump beams are important as it enables us to produce appropriate complex refractive index profile.
We have shown how the effect of paraxial diffraction can be partially eliminated during the propagation of optical images in a medium by pumping under the conditions of saturated absorption.
Further the transmission of an image without much loss of resolution as a result of diffraction is an important issue. The well-known limitation comes from the Rayleigh criterion which does not allow resolution of the features of an image beyond half of the optical wavelength with the use of conventional optics. Improving the resolution of an image has been a fundamental problem. This will have revolutionary impact in the area of optical communications and quantum information processing. The ability to slow down the propagation velocity of light and to coherently stop and store it, holds the key to the ultimate control of light. The recent demonstration on storage and retrieval of light in resonant media has tremendous technological implications. Furthermore the coherent control can also produce superluminal propagation of light as well as cloning of light pulses. It is also possible to store light in atomic coherences and to retrieve the light on demand. For example it is now possible to produce ultraslow light and even stop the light. An appropriate management of the dispersive and absorptive properties of a medium has led to remarkably very large number of applications. In particular, one could get distortionless propagation of pulses even through an absorbing medium.
The fundamental properties of a medium like dispersion and absorption can be manipulated by using appropriate coherent fields. In recent past, considerable success has been achieved in the precise control over the optical properties of the medium.