No abstract

We suggest a mechanism for the emergence of a superradiance burst in a subwavelength array of nonlinear classical emitters. We assume that the emitters interact via their common field of radiative response and that they may have an arbitrary distribution of initially phases. We show that only if this distribution is not uniform, a non-zero field of radiative response arises leading to a superradiance burst. Although this field cannot synchronize the emitters, it forces fast oscillations of a classical nonlinear emitter to have long-period envelopes. Constructive interference in the envelopes creates a large dipole moment of the array which results in a superradiance pulse. The intensity of the superradiance is proportional to the squared number of the emitters, which envelopes participate in the fluctuation.

Plasmonic distributed-feedback lasers based on a two-dimensional periodic array of metallic nanostructures are the main candidate for nanoscale sources of coherent electromagnetic field. Strong localization of the electromagnetic field and the large radiation surface are good opportunities for achieving an ultrashort response time to the external actions and creating beam directionality. At the same time, the investigation of such a system is a challenging problem. In this paper, we present an exhaustive study of the operation of a two-dimensional plasmonic distributed-feedback laser. We show that the complex structure of the modes of a periodic plasmonic array and the nonlinear interaction between the modes through the active medium lead to a new effect, namely, mode cooperation. Mode cooperation is manifested as the generation of the modes in an allowed band with a high threshold instead of modes localized near the band gap with a low threshold. Suppression of lasing of the modes at the edge of the band gap results in widening of the radiation pattern above the generation threshold. This paves the way for effective control and manipulation of the radiation pattern of nanoscale systems, which is of great importance for applications in spectroscopy and optoelectronics.

We theoretically study the role of strong coupling between an organic J-aggregated chromophore and a plasmonic nanostructure in the process of photobleaching suppression. We take into account the influence of vibrational degrees of freedom of nuclei in the molecules of J-aggregates in the Born–Markov approximation. We then show that in the strong coupling regime in this system, the stability of the J-aggregated chromophore increases by an order of magnitude. We also show that there is an optimal value of red detuning between the plasmon resonance frequency and the frequency of the dipole transition in the J-aggregate, for which the photobleaching suppression is most pronounced. We find this optimal value at different Rabi frequencies. Our results clarify the role of strong coupling between a plasmon structure near field and a molecular dipole moment in the process of photobleaching suppression and they pave the way for control of a chemical reaction in the vicinity of a plasmonic nanostructure.