Nanowire array lasers readily coupled to waveguides

June 13, 2017 // By Julien Happich
A multi-disciplinary team of researchers has demonstrated room-temperature InGaAs nanowire array lasers directly grown on a silicon-on-insulator (SOI) platform.

By growing periodically arranged InGaAs/InGaP core/shell nanowires aligned on a SOI substrate, the researchers created a one-dimensional (1D) photonic crystal cavity able to achieve a high quality (Q) factor comparable with two-dimensional competing solutions while requiring a much smaller footprint and less nanowires.

Publishing their results in Nano Letters under the title "The Monolithic InGaAs Nanowire Array Lasers on Silicon-on-Insulator Operating at Room Temperature", the international team of researchers also reveal that their optically-pumped lasers (at 660nm) made up of 21 nanowires (with a total cavity is only 6.7×0.14×0.8μm3) provide strong in-plane optical feedback, with the position of 11 nanowires in the centre linearly tapered to form an artificial defect to confine the field in the photonic bandgap.

Nanowire array laser monolithically integrated on SOI. (a) Schematic of the nanowire array laser on a planar SOI substrate. (b) Electric field profile of the fundamental cavity mode, showing tightly confined field in nanowires. (c,d) Thirty degree-tilted SEM images of an InGaAs/InGaP core/shell nanowire array laser (c) and close-up view (d). Scale bars, 500 nm (c) and 100 nm (d).

The aligned InGaAs nanowire arrays were grown on SOI substrates using a catalyst-free selective-area epitaxy technique, before being capped by InGaP shells to reduce non-radiative surface recombination. Lasing emission peaks at 1133nm with a quality factor of nearly 84,000 and this 1D array was efficiently coupled with SOI waveguides (by growing the nanowires on a pre-patterned SOI platform).