Scattering Dominated Spatial Coherence and Phase Correlation Properties in Plasmonic Lattice Lasers

TL;DR

This study investigates how scattering properties of individual particles influence the polarization and spatial coherence of lasing modes in a plasmonic lattice, revealing a transition from 1D to 2D coherence and phase locking of modes.

Contribution

It demonstrates the role of particle scattering in coherence and polarization changes in plasmonic lattice lasers, distinguishing effects from lattice geometry.

Findings

Transition from 1D to 2D spatial coherence with increasing particle size

Enhanced radiative coupling in diagonal directions at larger particle sizes

Degenerate lasing modes become phase locked with larger particles

Abstract

We present a comprehensive study of the polarization and spatial coherence properties of the lasing modes supported by a 4-fold symmetric plasmonic lattice. By modifying only, the scattering properties of the individual particles while keeping the lattice geometry constant, we are able to distinguish the scattering induced effects from the lattice geometry induced effects. Customized interferometric measurements reveal that the lasing emission undergoes a drastic change from 1D to 2D spatial coherence with increasing particle size, accompanied with dramatic changes in the far field polarization and beaming properties. By utilizing T-matrix scattering simulations, we reveal the physical mechanism governing this transition. In particular, we find that there exists increased radiative coupling in the diagonal directions at the plane of the lattice when the particle diameter is increased. Finally, we demonstrate that the x- and y-polarized (degenerate) lasing modes become phase locked with sufficiently large particles.