Optical metasurfaces, as artificially designed two-dimensional photonic materials based on micro-nano structures, can finely control the physical parameters of light fields, such as phase, amplitude, and polarization. When applied to light-emitting devices, the light field manipulation induced by optical metasurfaces enables precise regulation of the device's light-emitting properties, which has garnered widespread attention. We focus on the fabrication processes of optical metasurfaces and their application in light field manipulation within light-emitting devices. We introduce common micro-nano fabrication techniques for optical metasurfaces, provide an overview of the phase control mechanisms of metasurfaces, and summarize the recent research progress on the application of optical metasurfaces in light-emitting devices. We discuss the manipulation effects of optical metasurfaces on device emission characteristics, such as emission color, emission direction, emission polarization, and emission efficiency. Finally, we look forward to the future development and application prospects of optical metasurfaces and light-emitting devices based on optical metasurface light field manipulation.

The development of femtosecond pulse lasers has made it possible to generate and detect terahertz (THz) waves with frequencies between 0.1 THz and 10 THz. Terahertz ultrafast spectroscopy based on terahertz pulses is widely used in the study of physical properties for various materials. Due to the characteristic energy of superconductivity being mostly located in the terahertz frequency range, terahertz ultrafast spectroscopy has unique advantages in probing the excitation of various particles and quasi-particles in superconductors. This paper begins with an introduction to terahertz ultrafast spectroscopy and several related data analysis methods. It then reviews the application of terahertz ultrafast spectroscopy in high-temperature superconductors in detail, including the optical properties of equilibrium states, quasi-particle excitation, superconducting modulation, Higgs response, photo-induced superconductivity, and terahertz radiation from high-temperature superconductors. Terahertz ultrafast spectroscopy provides new insights into the rich physical phenomena in high-temperature superconductors and opens up new avenues for the development of terahertz optoelectronic devices based on high-temperature superconductors.