Optimizing Lasing Thresholds: Exploring the Impact of Pitch and Nanowire Diameter in InP Photonic Crystal Arrays
- 1Department of Physics, University of Cincinnati
- 2Department of Electronic Materials Engineering, Research School of Physics, Australian National University
Electrically-driven 2D photonic crystal (PhC) lasers show promise for on-chip coherent light sources in photonic integrated circuits, addressing speed, performance, and miniaturization needs. This study explores Wurtzite (WZ) InP nanowire (NW) arrays via selective area epitaxy on an InP substrate, focusing on PhC lattice constant (pitch) and NW diameter impact on the 77 K lasing threshold. NW arrays with pitches of 500, 570, and 630 nm, and diameters of 201, 187, and 175 nm, exhibit lasing at thresholds below 10 μJ/cm². Intriguingly, the lasing characteristics in certain PhC arrays cannot be explained by the conventional population inversion mechanism, suggesting a significant contribution of the valence B-band. Arrays with the lowest thresholds result from a pitch/diameter combination with a slow Bloch mode (SBM) nearly resonant with either A- or B-band emission. PhC samples with off-resonant higher SBM energy display elevated thresholds, explained by considering carrier relaxation and lifetime in the A- and B-bands. Optimizing InP nanowire arrays for low-threshold operation is an important step in advancing electrically-driven PhC lasers.