Ten years of spasers and plasmonic nanolasers

Plasmonic nanolasers and Spasers: Their evolution, properties, and future applications A review of plasmonic nanolasers charts breakthroughs in the technology over the past decade and points towards future research pathways and potential new applications. Plasmonic nanolasers, or spasers, are the counterparts of lasers, but instead of emitting photons, spasers emit composite particles made of photons and plasmons on the surfaces of metal nanoparticles. Their applications range from spectroscopic detection, on-chip light sources, and microscopy to optical sensors and probes. Now, an international team of researchers, led by Cun-Zheng Ning from Tsinghua University, has conducted a comprehensive review of the evolution spasers, from their first experimental demonstrations through to technological advances in the field and future research and new applications. After showing how the drive for miniaturization led to their creation, the review then summarises their properties and crucial progress made, and offers perspectives on unresolved issues and future challenges in the field. Ten years ago, three teams experimentally demonstrated the first spasers, or plasmonic nanolasers, after the spaser concept was first proposed theoretically in 2003. An overview of the significant progress achieved over the last 10 years is presented here, together with the original context of and motivations for this research. After a general introduction, we first summarize the fundamental properties of spasers and discuss the major motivations that led to the first demonstrations of spasers and nanolasers. This is followed by an overview of crucial technological progress, including lasing threshold reduction, dynamic modulation, room-temperature operation, electrical injection, the control and improvement of spasers, the array operation of spasers, and selected applications of single-particle spasers. Research prospects are presented in relation to several directions of development, including further miniaturization, the relationship with Bose-Einstein condensation, novel spaser-based interconnects, and other features of spasers and plasmonic lasers that have yet to be realized or challenges that are still to be overcome.