Surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA) are complementary techniques, and both provide fingerprint structural information on various materials with a high sensitivity. Herein, Zn–Al layered double hydroxides (LDHs) are proposed for the first time as highly sensitive and uniform substrates for both SERS and SEIRA. Zn–Al LDHs show a remarkable SERS effect with an enhancement factor (EF) as high as 1.637 × 10⁴ by using 4-mercaptobenzoic acid (4-MBA) as the probe molecule, where the charge transfer and hydrogen bonds are believed to result in the SERS effect. Interestingly, Zn–Al LDHs also exhibit SEIRA by using 4-methoxybenzenethiol (4-MTP), where the resultant substrates possess excellent long-term stability. This study not only presents a facile route to fabricate LDH materials, but also provides a novel substrate that can be used in both SERS and SEIRA.

A simple vibration sensor is proposed and demonstrated based on an optical fiber Fabry-Perot interferometer (FPI) with an in-fiber collimator. The device was fabricated by splicing a quarter-pitch graded index fiber (GIF) with a section of a hollow-core fiber (HCF) interposed between single mode fibers (SMFs). The static displacement sensitivity of the FPI with an in-fiber collimator was 5.17 × 10⁻⁴ μm⁻¹, whereas the maximum static displacement sensitivity of the device without collimator was 1.73 × 10⁻⁴ μm⁻¹. Moreover, the vibration sensitivity of the FPI with the collimator was 60.22 mV/g at 100 Hz, which was significantly higher than the sensitivity of the FPI without collimator (11.09 mV/g at 100 Hz). The proposed FPI with an in-fiber collimator also exhibited a vibration sensitivity nearly one order of magnitude higher than the device without the collimator at frequencies ranging from 40 to 200 Hz. This low-cost FPI sensor is highly-sensitive, robust and easy to fabricate. It could potentially be used for vibration monitoring in remote and harsh environments.

The next generation of communication 6G technology in the terahertz band is crucial for the development of the future high-speed information society. How to achieve a highly sensitive response to low power density terahertz signals at room temperature has been one of the frontier research hot issues within this field. In addition, the reproducible line height of the device and its availability for mass production are also urgent issues to be addressed. Here, We have proposed a 6G detector based on combining the advantages of sub-wavelength micro-structures, 3D micro-cavity, and Weyl-semimetallic films. The localized surface plasmon (LSP) effect by the micro-stud array is used for the enhancement of the light-matter interaction. Also, the 3D structure leads to a micro-cavity allowing for a near enhancement of the interaction on a small scale. Furthermore, the 0-band gap of the Weyl-semimetal and the enhanced response to low-energy photon displacement currents near makes the Weyl-semimetal more suitable for detecting terahertz waves. In addition, the use of projection micro stereolithography 3D print technology combined with magnetron sputtering of thin films makes this terahertz detection technology solution reproducible, low cost, simple processing, and promising for industrial production, contributing to the development and diffusion of 6G technology.

Instead of utilizing commercial detectors and a detection scheme based on 2D layer semiconductors or surface plasmon enhancement effect, we have developed a novel THz detector consisting of an array of microgrooves. This device combines the exceptional performance of materials with the localized surface plasmon (LSPs) effect in a sub-wavelength structure electromagnetic induced well detector. At room temperature, our device achieves a detectivity (D*) of 6.3×10 ⁸ cm Hz ^1/2 pW ^-1 and a responsivity (Rv) of 3.31×10 ⁵ V W ^-1 at 0.1 THz, with a 20 μm line spacing array. Furthermore, the effective detection area of our device is 6.5 mm × 2 mm, making it much more suitable for practical applications. These high-performance THz wave photodetectors open up possibilities for the effective detection of THz waves, which have wide-ranging applications in areas such as high-capacity communications, THz radar, biological diagnosis, and THz detection.

We demonstrate the HfSe ₂ saturable absorber (SA) for the generation of ultrafast pulse laser. The HfSe ₂ SA device is fabricated by integrating HfSe ₂ nanosheets (NSs) with a microfiber. The material and optical characteristics of HfSe ₂ NSs show their high quality. The nonlinear optical absorption of HfSe ₂ SA is measured with a modulation depth of 5.8%. Stable soliton mode-locked laser based on HfSe ₂ SA is realized at the central wavelength of 1561.43 nm with pulse duration of 297 fs and the maximum pulse energy of 2.68 nJ. Our soliton fiber laser has a maximum output power of 48.5 mW with a high slope efficiency of 12.8%, which indicate that HfSe ₂ is a good candidate of SA for high efficient ultrashort pulses generation.