An entirely different method of optical modulation is proposed for ultra-high-capacity fiber-optic communications. The proposed technique is based on dark-resonance induced susceptibility changes. I discuss hyper-THz optical modulation by utilizing two-photon refractive index changes.
An optical switching method based on dark resonance is proposed for ultrafast/ultrawide fibre-optic communications. The proposed switching method is based on dark-resonance induced refractive index changes in a three-level system interacting with two-colour laser lights. Two different mechanisms in the proposed optical switching method are discussed for the use of electromagnetically induced transparency and two-photon coherence induction. They are also compared for suitable applications in fibre-optic communications. Finally, a hyper-THz optical modulator is proposed, limited by current technologies due to carrier lifetime or population relaxation decay time.
An integrated photonic approach for complex quantum state generation through dynamical Casimir effect (DCE) is demonstrated. This approach provides a scheme to realize multipartite high-dimensional entangled states in the microwave (MW) and terahertz (THz) regimes, through the modulation in a MW-resonator coupled to an optical microresonator supporting temporal optical solitons. The states at the MW-resonator evolve from the ground state, realizing real-photons from the virtual photons at the ground state. The periodic modulation of the MW-resonator through a Kerr-induced refractive index change in the optical microresonator, along with the localized spatial distribution of the dissipative Kerr solitons (DKSs), enables photon-pair generation and inter-mode coupling at the MW-resonator. This allows generating highly persistent multipartite high-dimensional entangled states in a wide range of spectrum. The proposed approach paves the way for a hybrid integrated platform for generation of multipartite entangled qudits (high-dimensional qubits) at the MW and THz regimes using highly coherent ultra-short optical pulses in a monolithic integrated platform. This architecture can act as an entangled state source, as a necessary resource for exploiting a wide range of quantum protocols from fault-tolerant computing to enhanced sensing and teleportation.