Vertical emitting semiconductor nanowire lasers for monolithically integrated photonic circuits

With the advent of the post-Moore era and the rapid advancement of emerging industries such as artificial intelligence (AI) and the Internet of Things, there is an urgent demand for optoelectronic devices with ultra-small dimensions, ultra-high performance, ultra-fast response, and ultra-low power consumption. Benefiting from their extremely small size and exceptional physical properties, semiconductor nanowires (NWs) are regarded as one of the fundamental building blocks for next-generation optoelectronic devices. Vertical emitting NW lasers, offering significant advantages such as the ultra-small footprint, ultra-high integration density, and substantial tolerance to lattice mismatch, have gained increasing attention in recent years and demonstrated great potential for applications in Si-based optoelectronic integration. In this review, representative achievements of vertical emitting NW lasers are summarized in detail. The research background and significance of vertical emitting NW lasers are elaborated from the perspectives of the evolution of semiconductor lasers and the demands of the information industry. Methods of growing vertically aligned NWs, including catalyst-assisted and catalyst-free growth, are given. The structural designs of vertical emitting NW lasers, including the gain medium structure and resonant cavity configuration, are introduced. Different types of vertical emitting NW lasers, including single NW lasers, ordinary NW array lasers, NW photonic crystal lasers, NW topological lasers, as well as NW structured light lasers, are presented. The integration of vertical emitting NW lasers is briefly described. Finally, the related prospects and major challenges are discussed.