Plasmon Particle Array Lasers

Diffractive arrays of strongly scattering noble metal particles coupled to a high-index slab of gain material can form the basis for plasmonic distributed feedback lasers. In this chapter, we discuss recent theoretical and experimental results describing the electromagnetic properties of these structures. Particularly, we investigate bandgap topology versus detuning between the plasmonic and Bragg resonances. We examine the complex dispersion relation, accounting for the fact that the particles are electrodynamic scatterers with radiation loss, that couple via a stratified medium system supporting guided modes. From the complex dispersion of this array we can deduce loss and outcoupling properties of the various Bloch modes, giving a handle on its lasing properties. From the experimental side, we show how to measure the dispersion relation using fluorescence microscopy, and systematically examine the array dispersion for realized plasmonic lasers as function of detuning between particle and lattice resonance. We conclude the chapter with a vision towards employing disordered, quasiperiodic and random plasmonic arrays to induce different optical responses, and experimentally demonstrate the exceptional robustness of lasing to disorder in these systems.