مشخصات پژوهش

Finding materials with high and tunable optical response can have very interesting applications in the design of photonic devices. It is shown that the addition of Co2+ ions with half-filled d-orbitals creates deep and tunable intermediate energy levels in the CdS band gap, which directly controls the intensity and mechanism of the nonlinear response. By changing the Co concentration, the dominant mechanism may switch from two-photon absorption and nonlinear Kerr effect to saturable inverse absorption and then to free-carrier absorption. This allows for a systematic study of the concentration-dependent behavior and a precise determination of the optimal concentration for maximum χ³ and optical confinement performance. This system has a better resonance with the 532 nm laser than other common dopants (Mn, Cu, Ni), and its complete and systematic investigation at different cobalt concentrations using the z-scan technique has not been reported so far, and is innovative of the problem.