A multiplex localized surface plasmon resonance (LSPR) temperature sensor based on grapefruit fiber filled with a silver nanoshell (SNS) and liquid is designed and characterized by the finite element method. Due to the plasmon hybridization in SNS, the designed sensor supports two separate intense LSPR bands that can realize dual-channel temperature sensing at the same time by altering the light wavelength. When temperature increases from 20°C to 80°C, two LSPR bands shift to the shorter wavelength in good linear relationships with wavelength sensitivities of −1.14 and −0.86  nm  /    °  C. The maximum amplitude sensitivity can reach 0.77  °  C^−  1 for peak I with the resolution of 0.01°C. Moreover, the full width half maximum of peak I is <5  nm, exhibiting much better figure of merit than other works, which can provide a new way for multiplex temperature sensing of fiber sensors.

We theoretically and experimentally demonstrated an all-fiber, hundred-watts-level, linearly-polarized, narrow spectral linewidth laser amplifier at a central wavelength of 1018 nm based on master oscillator-power amplifier configuration, which is composed of a laser oscillator and one stage of the fiber amplifier. The laser system can generate 104-W output power with 3- and 20-dB spectral linewidth of ∼0.073 and ∼0.25  nm, respectively, and a higher polarization extinction ratio of ∼17.89  dB at 1018.3 nm was obtained. Theoretical analysis based on the rate equations was used to optimize the parameters of 1018-nm ytterbium-doped fiber laser system for the maximum suppression of amplified spontaneous emission (ASE). The ASE was well depressed based on the optimization for the parameters of the laser system including the seed power, seed spectrum, gain fiber length in the amplifier, etc. And   ∼  27-dB signal-to-noise ratio was achieved at the maximum output power. The slope efficiency for the amplifier stage can reach 79%, and near-diffraction-limited beam quality (Mx2∼1.617 and My2∼1.635) was obtained.

A lead selenide (PbSe) NC-based phototransistor memory (PTM), wherein graphene oxide (GO) sheets covered by Au nanoparticles (NCs) act as double charge trapping layers, is studied under near-infrared (NIR) light. The memory window (ΔV_th) can be significantly enlarged by light-assisted programming and erasing processes, wherein the photogenerated carriers in a PbSe NCs channel can be trapped and detrapped by the GO/Au NCs charge-trapping layers. The PTM achieved an enhanced ΔV_th from 0.7 V in the dark to 1.8 V under the NIR light, due to the increasing number of photogenerated charges due to the NIR light. The PTM exhibited high responsivity (R), external quantum efficiency (EQE), and detectivity (D  *  ) of about 13.9  A  /  W, 2.2  ×  10³  %  , and 1.5  ×  10⁸ Jones, respectively. Due to the good photoresponsibility of the PbSe NCs, the PTM exhibited a large ΔV_th under low programming/erasing voltages under the NIR light and realized multilevel memory. The results presented on photoassisted memory may pave a way to large-area, flexible, low-temperature fabrication, and photoreactive memory devices.

A chloride ion sensor based on a multitaper modulated fiber fabricated via arc discharge is proposed and studied experimentally and theoretically. The sensing unit consists of four periodic tapers with a diameter of 28.24  μm, a period of 676  μm, and a total length of 2.7 mm. The results show that the concentration sensitivity values are 170 pm/(g/L) at a wavelength of 1303.60 nm and 220 pm/(g/L) at a wavelength of 1389.84 nm when the chloride ion concentration is increased from 0 to 40 g/L. The proposed sensor is characterized by a simple manufacturing process, a compact structure, and a low cost, and this sensing unit has great potential for application in marine chloride detection and environmental safety monitoring, especially for monitoring building corrosion and water pollution.

The dielectric properties of 0.55SrTiO₃-0.45NdAlO₃ ceramics under external optical fields were investigated by terahertz time-domain spectroscopy at room temperature. From the experimental results, it could be found that the tunability of permittivity with the external optical pump was reached up to 16% at 0.6 THz. And the change of refractive index has a linear relationship on scale with the applied external light power. These results could be explained by a built-in electric field caused by the excited free carriers in the ceramics.