Cover story: Zhang FL, Su ZC, Li Z, Zhu Y, Gagrani N et al. High-speed multiwavelength InGaAs/InP quantum well nanowire array micro- LEDs for next generation optical communications. Opto-Electron Sci 2, 230003 (2023).

On-chip optical networks utilize light for data transmission, offering significant advantages over electrical signals, including faster speed, higher bandwidth and lower power consumption. Key to on-chip optical networks are miniaturized light sources such as micro-/nano-scale lasers or light-emitting diodes (LEDs). However, most developments on micro-/nano LEDs are based on III-nitride material systems at visible wavelengths; there have been limited reports on high-speed infrared micro- LEDs at telecommunication wavelengths. Epitaxial grown In(Ga)As(P)/InP nanowires hold great potential for miniaturized LEDs and lasers at telecommunication wavelength range, as their wide bandgap tunability could enable monolithic integration of multi-wavelength light sources on a single chip through a single epitaxial growth, which could boost the data transmission capacity by wavelength division multiplexing (WDM) and multiple-input multiple-output (MIMO) technologies. Recently, the research team led by Profs. Lan Fu and Chennupati Jagadish at the Australian National University demonstrated the selective-area growth and fabrication of highly uniform p-i-n core-shell InGaAs/InP single quantum well (QW) nanowire array LEDs. The QW nanowire LEDs exhibited strong bias-dependent electroluminescence, covering telecommunication wavelengths (1.35~1.6 μm). The compatibility of the nanowire array LEDs with WDM and MIMO technologies for high-speed communication was further illustrated by the monolithic growth of nanowire array LEDs on the same substrate with different pitch sizes (and thus different emission wavelengths), GHz-level modulation and much-reduced array sizes (< 5 μm in width), indicating a promising pathway for the development of nanoscale on-chip light sources for next generation highly integrated optical communication systems.