Enhanced Lasing from InP Hetero-PCSEL Nanowire Arrays

Electrically driven 2D photonic crystal lasers play a crucial role in advancing miniaturization and efficiency in photonic technologies. We investigate the optically pumped lasing characteristics of InP nanowire (NW) hetero-PCSELs (Photonic Crystal Surface Emitting Laser) which consist of a hexagonal shaped NW inner array surrounded by an outer NW array. Both arrays have the same hexagonal lattice constant (pitch) of 500 nm but different NW diameters such that the laser light generated from the inner array is forbidden from propagating into the outer array. Instead, it is back reflected at the heterostructure interface enhancing the cavity resonance and leading to reduced lasing thresholds. A series of samples of differing side lengths were studied ranging from 15 to 1.5 μm under pulsed and continuous excitation. At 77 K, an optimum pulsed threshold fluence reduction from 18 to 3 μJ/cm² is observed when transitioning from a conventional reference PCSEL to the hetero-PCSEL with an inner region of side length 5 μm. Under continuous wave excitation at 77 K, the reference PCSEL shows no laser emission while the heterostructures with different inner regions having side lengths of 15 to 3 μm show lasing thresholds ranging from 17 to 5 kW/cm².