Razi University

In this thesis‎, ‎we investigate optical bistability in hybrid optomechanical systems involving quantum dot molecules and nonlinear Kerr media in two-cavity and three-cavity configurations‎. ‎For this purpose‎, ‎first‎, ‎the basic concepts of linear and nonlinear optics are reviewed and the properties of quantum dot molecules as an important and highly tunable nanostructure are introduced‎. ‎Next‎, ‎the basic concept of radiation pressure is discussed and optomechanical systems are studied from classical and quantum perspectives‎. ‎To analyze optical bistability in the proposed optomechanical systems and to consider the effect of environmental dissipation‎, ‎the Heisenberg-Langevin approach is used‎. ‎Based on this approach‎, ‎the dynamic equations governing the hybrid optomechanical structures are derived‎. ‎By applying the mean-field approximation and considering the steady-state regime‎, ‎an analytical equation for the average number of photons inside the cavity is obtained‎. ‎Due to the nonlinear nature of this equation‎, ‎the optical bistability behavior of the system is subsequently investigated‎. ‎Furthermore‎, ‎the effects of various system parameters‎, ‎including frequency detuning‎, ‎optomechanical coupling strength‎, ‎intercavity coupling strength‎, ‎and quantum dot molecule tunneling coupling strength‎, ‎on the optical bistability‎, ‎upper and lower switching thresholds‎, ‎and bistability amplitude are systematically investigated‎. ‎These features are of considerable importance for the realization of all-optical switches‎, ‎optical memories‎, ‎phototransistors‎, ‎and photorectifiers‎. ‎Furthermore‎, ‎the proposed hybrid optomechanical systems are used for all-optical computing‎, ‎quantum computing‎, ‎and ultra-precision measurements‎.