Structured light refers to custom light fields with tailored phase, intensity or polarization. In the recent advances in the field, several classes of complex light beams with novel properties have been experimental produced, and have been successfully applied in many fields, such as Laguerre–Gaussian, elegant Gaussian beams, nondiffracting Bessel beams, accelerating light fields Airy beams. The structured light has found a wide variety of applications, such as optical manipulation, optical metrology, optical imaging, classical optical communications and quantum communications.  This feature issue will highlight research spanning all fields influenced by structured light. We encourage papers that are application based, exploring the use of structured light.

The advanced equipment manufacturing industry demands high-precision, versatile, and multi-dimensional geometric measurements. Multi-channel laser ranging technology offers a unified sensing approach, minimal error sources, and high measurement efficiency. Frequency modulated continuous wave (FMCW) laser measurement technology, with its high precision, wide dynamic range, strong anti-interference capability, and high signal-to-noise ratio, enables precise absolute distance measurements of large-scale, non-cooperative targets. It holds significant potential for industrial applications such as precision machining, equipment assembly positioning, and multi-dimensional surface scanning.

Researchers from Peking University Yangtze Delta Institute of Optoelectronics, have proposed a universal design scheme for discrete whispering gallery mode (WGM) microcavity devices. The developed devices achieve an exceptional quality factor (Q) of up to 1 billion while maintaining remarkable robustness. On this platform, the team has successfully demonstrated low-threshold (4mW) and low-noise (-103dBc/Hz10kHz) soliton microcombs. This groundbreaking research provides an innovative technological pathway for advancing both fundamental research and engineering applications in microcavity-based precision measurement and microwave photonics.

Optical frequency combs (OFCs) are characterized by a comb-like structure in the frequency domain, where the frequency spacing between the comb teeth is equal, and the phases are mutually locked. OFCs have widespread applications in precision measurements, spectroscopy, and optical communications. In particular, in the field of microwave photonics, optical frequency combs serve as a bridge linking the optical frequency domain and the radio frequency (RF) domain. Among various OFC generation techniques, cascaded electro-optic modulator (EOM)-based combs have garnered significant attention in academia due to their inherent advantages, such as flexible control of comb tooth spacing (FSR), adjustable comb line number, and insensitivity to optical wavelength.