Single-mode lasing of GaN nanowire-pairs

Abstract

Stable single-mode lasing operation from a pair of coupled GaN nanowires is demonstrated through optical pumping. GaN nanowires with different lengths were placed side-by-side in contact to form a coupled cavity through nanoprobe manipulation. Unlike individual nanowire lasers, which operate in a combined multiple transverse and multiple longitude mode oscillation, a coupled nanowire-pair provides a mode selection mechanism through the Vernier effect, which can strongly enhance the free spectrum range between adjacent resonant modes and generate a stable single-mode operation with a high side-mode suppression ratio.

Gold substrate-induced single-mode lasing of GaN nanowires

“…A minimum spacing of $0.58 nm is observed, much smaller than the calculated longitudinal mode spacing of $2.1 nm for single transverse-mode operation. 9 Taken together, these spectral features are indicative of multiple transverse-mode operation of the GaN nanowire laser. 9 Fig.…”

“…9 In order to obtain single-mode operation, it is necessary to introduce a multimode suppression technique to the nanowire cavity. Previously, we have demonstrated that multiple longitudinal-mode oscillation in GaN nanowires can be suppressed by reducing the nanowire length to $5 lm, at which point the mode competition is strongly enhanced in the cavity.…”

Nanowire Lasers

“…Mode selection was performed and only one mode was stimulated at the end using two GaN nanowires coupled side by side [110]. Yang et al from Berkeley University followed the same principles, except for performing the coupling axially rather than radially [29].…”

Annular-Shaped Emission from Gallium Nitride Nanotube Lasers

“…In order to maximize the potential of nanowire lasers, a greater understanding and control over their properties, including mode control, polarization control, wavelength tuning, and beam shaping, is necessary. Recently, single mode emission from GaN nanowire lasers was demonstrated via several routes, including size (diameter and length) control 6 , coupled nanowires [7][8][9] , distributed feedback 10 , and placement onto a metal substrate, which induces a mode-selective loss 11 . Wavelength tuning of GaN nanowire lasers was demonstrated using GaN/InGaN nanowire photonic crystal arrays 12,13 , hydrostatic pressure 14 , and bandgap graded nanowires 15,16 .…”