Innovation in metamaterials and beyond:an interview with Prof.Xiang Zhang

Ren-Min Ma: Prof. Zhang, you have made a series of groundbreaking discoveries in metamaterials. How did you get started in this field?Xiang Zhang: The research in metamaterials started about two decades ago. We are very lucky to have worked in this field from the very beginning, especially with John Pendry and David Smith.

Twisted lattice nanocavity with theoretical quality factor exceeding 200 billion

Simultaneous localization of light to extreme spatial and spectral scales is of high importance for testing fundamental physics and various applications.However,there is a longstanding trade-off between localizing a light field in space and in frequency.Here we discover a new class of twisted lattice nanocavities based on mode locking in momentum space.The twisted lattice nanocavity hosts a strongly localized light field in a 0.048𝜆3 mode volume with a quality factor exceeding 2.9×1011(∼250𝜇s photon lifetime),which presents a record high figure of merit of light localization among all reported optical cavities.Based on the discovery,we have demonstrated silicon-based twisted lattice nanocavities with quality factor over 1 million.Our result provides a powerful platform to study light-matter interaction in extreme conditions for tests of fundamental physics and applications in nanolasing,ultrasensing,nonlinear optics,optomechanics and quantum-optical devices.

Ten years of spasers and plasmonic nanolasers

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.

Twisted phonon polaritons at deep subwavelength scale

Hyperbolic polariton vortices carrying reconfigurable topological charges have been realized at deep subwavelength scale.

Lasing-enhanced surface plasmon resonance spectroscopy and sensing

Surface plasmon resonance(SPR)sensors are a prominent means to detect biological and chemical analytes and to investigate biomolecular interactions in various fields.However,the performance of SPR sensors is ultimately limited by ohmic loss,which substantially weakens the resonance signal and broadens the response linewidth.Recent studies have shown that ohmic loss can be fully compensated in plasmonic nanolasers,which leads to a novel class of lasing-enhanced surface plasmon resonance(LESPR)sensors with improved sensing performance.In this paper,we detail the underlying physical mechanisms of LESPR sensors and present their implementation in various sensing devices.We review recent progress on their applications,particularly for refractive index sensing,gas detection and biological imaging,labeling,tracking,and diagnosis.We then summarize the review and highlight remaining challenges of LESPR sensing technology.