Conventional methods for near-field characterization typically relied on the nanoprobe to point-scan the field, rendering the measurements vulnerable to external environmental influences. Here,

Conventional methods for near-field characterization typically relied on the nanoprobe to point-scan the field, rendering the measurements vulnerable to external environmental influences. Here, we study on the direct far-field imaging of the near-field polarizations based on the four-wave mixing effect. We construct a simulation model to realize the instantaneous extraction of the near-field distributions of a wide range of structured light fields, such as cylindrical vector vortex beams, plasmonic Weber beams, and topological spin textures including photonic skyrmions and merons. This method is valuable for the studies on manipulation of structured light fields and light-matter interaction at micro/nano scales.show less

Defects are induced during the fabrication process of a metalens inevitably, which will affect its yield and optical performances. Thus, the investigations on the fabrication defects are becomin

Defects are induced during the fabrication process of a metalens inevitably, which will affect its yield and optical performances. Thus, the investigations on the fabrication defects are becoming increasingly important for mass-production of metalenses. In this letter, optical performances of near-infrared metalenses with four types of fabrication defects are investigated. The results show that the process-induced defects affect the focusing efficiency at λ = 940 nm obviously, but have less impact on the quality of the focal spot. This work providing the fabrication guidance for the large-scale manufacturing of metalenses in future.show less

With the development of big data era, the need for computation power is dramatically growing, especially for solving partial differential equations (PDEs), since PDEs are often used to describe

With the development of big data era, the need for computation power is dramatically growing, especially for solving partial differential equations (PDEs), since PDEs are often used to describe complex systems and phenomena in both science and engineering. However, it is still a great challenge for on-chip photonic solving of time-evolving PDEs because of the difficulties in big coefficient matrix photonic computing, high accuracy and error accumulation. Here, we overcome these challenges by realizing a microcomb-driven photonic chip and introducing time division multiplexing and matrix partition techniques into PDE photonic solving, which can solve PDEs with large coefficient matrix on a photonic chip with limited size. Time-evolving PDEs, including Heat equation with first order of time derivative, wave equation with second order of time derivative and nonlinear Burgers equation are solved with accuracy up to 97%. Furthermore, the parallel solving of Poisson equation and Laplace’s equation are also demonstrated experimentally on a single chip, with accuracy of 95.9% and 95.8%, respectively. This work offers a powerful photonic platform for solving PDEs, which makes a pace forward in the application of photonic chips in mathematical problems and will promote the development of on-chip photonic computing.show less

This letter presents an active coherent beam combining (CBC) of a pulsed laser based on sampling the intrapulse evaluation function. By precisely controlling trigger sequence of an analog-to-dig

This letter presents an active coherent beam combining (CBC) of a pulsed laser based on sampling the intrapulse evaluation function. By precisely controlling trigger sequence of an analog-to-digital converter (ADC), fixed time point of the pulse light is sampled as evaluation function for CBC. The active CBC of two fiber amplifiers with a 500 ns pulse width and 10 kHz repetition rate is experimentally demonstrated by applying a hill climbing algorithm. The residual phase error is approximately λ/27. A coherent Doppler wind lidar (CDWL) based on CBC light source is verified.The experimental results verify the feasibility of using the pulsed CBC to improve the pulse energy of a CDWL without degrading performance.show less