Conventional electronic devices rely on manipulating charge to produce desired functions,rnspintronic devices would manipulate both the charge flow and electron spin withinrnthat flow. This would add an extra degree of freedom to microelectronics and usher inrnthe era of truly nanoelectronic devices. Research aimed at a whole new generation ofrnelectronic devices is underway by introducing electron spin as a new or additional physicalrnvariable, and semiconductor devices that exploit this new freedom will operate fasterrnand more efficiently than conventional microelectronic devices and offer new functionalityrnthat promises to revolutionize the electronics industry.rnIn order to enable electronic devices in active part of operation efforts have been madernto develop diluted magnetic semiconductors(DMS) in which small quantity of magneticrnion is introduced in to normal semiconductors. The first known such DMS are II-VI andrnIII-V semiconductors diluted with magnetic ions like Mn, Fe, Co, Ni, etc. Most of thesernDMS exhibit very high electron and hole mobility and thus useful for high speed electronicrndevices.rnIn this thesis we study a photo induced ferromagnetism and mechanism of ferromagnetismrnin diluted magnetic semiconductors by solving a Hamiltonian model that consistsrnof localized magnetic moments interacting with photoexcited carriers. The mechanismrnfor photo-induced ferromagnetism is coherence between conduction and valence bandsrninduced by the light which leads to an optical exchange interaction. When light is incidentrnon the diluted magnetic semiconductors, electron and holes are created across thernband gap. Photo excited carriers mediated a ferromagnetic interaction between the localizedrnmoments resulting in ferromagnetic state in the range of critical temperature. Thernixrnsituation is similar to the famous Rabi problem of a two state system coupled to timedependentrnoscillating electric field. The time dependance of the light-matter interactionrnterm is eliminated by a unitary transformation and the resulting Hamiltonian is solvedrnby making a Bogoliubov-Valtain transformation. Since the system of electrons and holesrnin contact with the photon bath is considered in a steady state, we calculate the freernenergy of the system. Starting the free energy again we calculate the magnetization ofrnthe system in self-consistent mean field way. The magnetization and magnitude of Tc isrndetermined by the photon energy incident on the system. By increasing the light couplingrnand frequency of the light, the transition temperature is increased