Polarization dependent beaming properties of a plasmonic lattice laser

Abstract

We study beaming properties of laser light produced by a plasmonic lattice overlaid with organic fluorescent molecules. The crossover from spontaneous emission regime to stimulated emission regime is observed in response to increasing pump fluence. This transition is accompanied by a strong reduction of beam divergence and emission linewidth due to increased degree of spatial and temporal coherence, respectively. The feedback for the lasing signal is shown to be mainly one-dimensional due to the dipolar nature of the surface lattice resonance. Consequently, the beaming properties along x and y directions are drastically different. From the measurements, we obtain the M 2 value along both principal directions of the square lattice as a function of the pump fluence. Our work provides the first detailed analysis of the beam quality in plasmonic lattice lasers and reveals the underlying physical origin of the observed strong polarization dependent asymmetry of the lasing signal.

Scattering dominated spatial coherence and phase correlation properties in plasmonic lattice lasers

“…These various degrees of freedom indicate that many areas of the parameter space may still be unexplored, even in some of the simplest cases. For instance, in the case of square lattice symmetry with cylindrical particles, the polarization dependence of the radiative feedback and the consequent anisotropy of the spatial coherence of lasing has only recently been recognized [15]. The results from [15], suggest that since the feedback mechanism is based on radiative coupling, the directionality and the polarization dependence of the nanoparticle scattering govern the spatial coherence properties of the laser.…”

“…For instance, in the case of square lattice symmetry with cylindrical particles, the polarization dependence of the radiative feedback and the consequent anisotropy of the spatial coherence of lasing has only recently been recognized [15]. The results from [15], suggest that since the feedback mechanism is based on radiative coupling, the directionality and the polarization dependence of the nanoparticle scattering govern the spatial coherence properties of the laser. Thus, the control over the scattering properties of the particles (and radiative feedback) could play a crucial role also for the beaming properties of these coherent light sources.…”

Elliptically Polarized Plasmon Resonances for Optical Polarization and Phase Control

“…Despite these properties, there remains limited control over polarization because SLR is commonly mediated by linearly polarized dipole resonances within the structures. ,− Achieving elliptical or circular polarization within a structure requires the ability to specify a phase and amplitude relationship between two orthogonal dipole resonances. Realizing elliptically polarized resonances could allow for the development of plasmonic lattice lasers with elliptically polarized beams because the scattering from the lattice is mediated by the structures .…”

Loss-driven topological transitions in lasing

“…The impossibility of defining a propagation wavevector at the center of a vortex makes the BICs appear dark in the far-field radiation. BICs can be weakly coupled to the radiative continuum via an intentionally designed leakage mechanism or due to material loss [4,5,15]; the presence of an edge can also act as a leakage channel [16,17]. In this way, quasi-BICs of extremely large Q-factors can be observed [18][19][20][21][22][23][24][25].…”

“…BICs of topological charge |q| = 1 have been observed in many systems, from photonic crystals to nanoplasmonic structures [4,13,14,16,17,[26][27][28]. Switching between non-degenerate BICs with different topological charge of |q| ≤ 1 was recently achieved [28].…”