STRONG-FIELD INDEX ENHANCEMENT VIA SELECTIVE-POPULATION OF DRESSED STATES

A three-level Lambda scheme is proposed in order to achieve a large (r esonant) index of refraction with vanishing absorption. This scheme is based on the selective population of one of the dressed states produc ed by a strong laser field. For modest values of the density and reali stic atomic parameters the present scheme gives the index to absorptio n ratio approximate to 2500. It is to be noted that an off-resonant tw o-level scheme can also give such a ratio but the index of refraction will be smaller. The present approach to index enhancement is not limi ted to weak fields, as is the case in some other schemes. [S1050-2947( 97)00212-6].