Fiber optic imaging systems (FOISs) play a critical role in clinical practice and biological research due to their flexibility and small size, such as medical fiber endoscopes for imaging the inside of natural human tubes or surgical incisions, and deep tissue imaging microscopes. A multimode fiber (MMF) supports the simultaneous propagation of over hundreds of optical modes through a hair-thin imaging probe, further reducing the invasiveness of FOIS, which gives MMF-based imaging systems great potential in the field of medical endoscopy. However, the imaging resolution of MMFs is inevitably limited by their inherent physical conditions. Especially for an ultrafine core diameter MMF, the limited spatial mode quantity becomes the bottleneck to achieve high resolution imaging. To break this limitation and fully unlocked the imaging potential of MMF, the team has proposed a mode modulation method based on singular value decomposition. This method can autonomously modulate the excitation modes of MMF during transmission, and significantly improve the imaging quality of MMF-based imaging systems. For the ultrafine 40μm core MMF, the image reconstruction accuracy achieved an increase of up to 7.32dB in peak signal-to-noise ratio (PSNR) and 0.103 in structural similarity (SSIM). This study is expected to promote the further development of MMF imaging towards lower invasiveness and higher resolution, and has great value in the field of MMF-based medical endoscopy imaging. Relevant research results were recently published in Photonics Research, Volume 12, Issue 10, 2024. [Ning Zhan, Zhenming Yu, Liming Cheng, Jingyue Ma, Jiayu Di, Yueheng Lan, Kun Xu, "Enhanced ultrafine multimode fiber imaging based on mode modulation through singular value decomposition," Photonics Res. 12, 2214 (2024)]

Optical forces are crucial in understanding light–matter interactions across various scientific fields, including atomic physics, optics, photonics, and nanotechnology. Since the advent of laser tweezers, significant advancements have been made in optical trapping, binding, sorting, and transporting particles using optical forces. Current research focuses on enhancing control over different types of optical forces to better manage the dynamics and interactions of microparticles and nanoparticles.

In recent years, bound states in the continuum (BIC), have attracted much attention because of their infinite photon lifetime and quality factor, and their applications in enhancing light-matter interactions. However, optical BIC or quasi-BIC structures are generally machined by metamaterial/ metasurface/ photonic crystal of metal or dielectric materials. Once the structural parameters are determined, it is difficult to realize the active regulation of the device, which greatly limits its functionality and application scenarios. The combination of tunable materials with metamaterials or metasurfaces provides an effective way to realize tunable terahertz (THz) quasi-BIC devices. In particular, liquid crystal (LC) has large birefringence and low absorption loss in the THz band, and its orientation can be actively controlled by external electric, magnetic or light fields, which is a very effective THz active material. At present, metasurfaces based on liquid crystal integration have attracted much attention due to their advantages in the tunable control of electromagnetic waves.