Hybrid Plasmonic Coupled Nanophotonic Cavity-Mediated Tunable Nonlinear Absorption in Cobalt Phthalocyanine

Light-matterinteraction in subwavelength-scale opticalconfinement structures is a hot topic in basic science and the photonicindustry. Materials experiencing high electric field strength canchange their optical properties according to the intensity of light,as governed by the laws of nonlinear optics. In this paper, we investigatethe linear and nonlinear optical behavior of cobalt phthalocyanine(CoPc) placed in the combined local fields of plasmonic and photoniccavity modes. Using polymeric layers, we created a planar microcavityand embedded the cavity layer with CoPc/Au nanocomposites. The enormousfield strengths caused by the cavity photon-plasmon couplingsignificantly enhance the nonlinear optical absorption of the CoPc.The combination of photon-plasmon-exciton interactionsin the hybrid microcavity results in an enhancement of the excited-stateabsorption of the system, even at low excitation intensities. Thedegree of light coupling can be altered by tuning the angle of lightincidence, thereby varying the nonlinear transmittance of the microcavitystructure. The proposed system can act as an angle-tunable nonlinearoptical switch that works for laser pulses, with high attenuationat normal incidence and high transmittance at oblique incidence. Ourfindings provide a comprehensive understanding of the resonant light-matterinteractions in tailored photonic crystal structures and how theseinteractions nonlinearly alter the optical properties, with potentialfor use in photonic applications.

Automated summary

In this study, the linear and nonlinear optical behavior of cobalt phthalocyanine (CoPc) in the combined local fields of plasmonic and photonic cavity modes were investigated. A planar microcavity was created using polymeric layers and embedded with CoPc/Au nanocomposites. The strong field strengths caused by the cavity photon-plasmon coupling significantly enhanced the nonlinear optical absorption of CoPc. The proposed system can act as an angle-tunable nonlinear optical switch with potential applications in photonics.