Nonlinear Switching mechanism in nanostructures doped in photonic crystals

We have investigated the nonlinear switching mechanism in nanostructures doped in photonic crystals. The nonlinear phenomenon studied in this paper is the two-photon absorption process. A probe laser field is applied between the ground state and the next excited state of the nanoparticles to measure the two-photon absorption spectrum. A coupling field is applied between the two excited states of nanoparticles to control the two-photon process. It is found that when the decay resonance energy lies away from the photonic band edge the inhibition of two-photon absorption is observed. However, when the probe field is not resonance, the inhibition of two photons absorption is not observed. An interesting result is observed when the decay resonance energy lies near the band edge. It is found that the inhibition of the two-photon absorption disappears. It means that the phenomenon of two-photon absorption can be switched on and off by tuning the resonance energy within the lower band of the crystal. This mechanism can be used to make a new type of photonic switching devices using photonic crystals.