Optical nanotweezers based on all-dielectric resonant structures

In recent years, various optical nanotweezers based on all-dielectric structures with low loss and high electromagnetic field enhancement have been proposed, such as single dielectric nanoantenna tweezers, anapole-enhanced tweezers, dielectric metasurface tweezers, and on-chip waveguide tweezers, and demonstrated great application potential in many fields such as biochemistry and cell detection. Thus, in this paper, we review the recent research progress in optical nanotweezers based on dielectric resonant structures, which is of great significance for advancing the development and application of optical tweezers technologies. We classified the research works in this field into two main categories based on the excitation methods of electromagnetic field hotspots: off-chip light source excitation and on-chip light source excitation. Within these categories, we further analyzed and introduced techniques from simple dielectric structures to complex dielectric structures and from low to high-dimensional structures. For the optical nanotweezers based on the off-chip light source excitation, we expand from simple single dielectric nanoantenna structure-based trapping techniques to periodic structure array-based trapping techniques, followed by non-periodic dielectric metasurface-based tweezers techniques and optical fiber facet microstructure-based tweezers techniques. For the optical nanotweezers based on the on-chip light source excitation, we introduce the simple waveguide trapping techniques, followed by the relatively complex photonic crystal array trapping techniques, and further introduce the on-chip lens trapping techniques. Finally, we summarize the above techniques and forecast the future development trends of the all-dielectric structure-based optical nanotweezers.

The optical nanotweezers technologies utilizing dielectric resonant structures have shown the ability to offer novel and robust electromagnetic field resonance enhancement mechanisms, such as BIC and Anapole mode, while minimizing thermal effects. Additionally, these structures enable the reduction of system dimensions to the micro- or even nano-scale, making them a promising research aspect for the development of optical tweezers technologies. A summary of the key technical indicators and parameters of these technologies is provided in Table 1 for comparative analysis. Future advancements of these technologies will focus on four frontiers: exploration of more easily excitable dielectric resonance modes with increased enhancement factors; achieving richer dynamic manipulation effects by combining different resonance modes, chiral structures, and structured light fields; the integration of high-throughput optical manipulation technologies with microfluidic chips for large-scale, high-throughput cell and virus detection; expanding more application scenarios such as nano-robots for drug delivery and quantum computing. By combining various materials, intricate structural designs, and innovative resonance effects, the future dielectric structure-based optical tweezers will become more flexible, integrated and multifunctional, and many new applications in this area will be developed.