Showing papers by "Jinhui Yuan published in 2023"

Switchable multi-wavelength fiber laser based on a taper-coupled microbottle resonator

Abstract: • A taper-coupled microbottle resonator as high Q factor comb filter was applied in erbium-doped fiber laser. • This laser can achieve the switchability in up to quint-wavelength output laser states. • This laser system has good stabilities in laser wavelength shift and power fluctuation. A multi-wavelength erbium-doped fiber laser (EDFL) based on a taper-coupled microbottle resonator is proposed and investigated experimentally. The taper-coupled microbottle resonator has the comb filter characteristics with Q factor 2.9 × 10 4 , which is integrated into an EDFL system. The taper-coupled microbottle resonator was packaged by ultraviolet glue, which has excellent stability of output power and wavelength at room temperature. Then, switchable dual-, triple-, quad- and quint-wavelength fiber laser states can be achieved by adjusting the polarization controller (PC). Furthermore, for dual-wavelength and triple-wavelength laser state, the position of output wavelengths also can be precisely modulated with the PC. The developed multi-wavelength EDFL has the optical signal to noise ratio as high as 40 dBm, and the wavelength shift and peak power fluctuation are less than 0.03 nm and 6 dBm.

Highly Sensitive Dual-Core Microstructured Fiber Sensor Operating Near the Dispersion Turning Point

Abstract: In this article, a highly sensitive dual-core microstructured fiber (DC-MSF) sensor is proposed. Because of the adjustable dispersion characteristic of the DC-MSF, the group refractive index (RI) difference between the ${y}$ -polarization odd and even supermodes could achieve a zero value at the dispersion turning point (DTP), which makes the DC-MSF sensor have a high sensitivity. The simulation results show that the sensitivity can be up to 52 875 nm/RIU around the RI of 1.4, the operating bandwidth of sensitivity over 104 nm/RIU is 625 nm, and the operating bandwidth of sensitivity over 105 nm/RIU is 100 nm. Moreover, the DC-MSF can also be used as a temperature sensor by coating the polydimethylsiloxane (PDMS) on the surface, and the sensitivity can be up to 23.12 nm/°C around 22 °C. The detectable RI and temperature ranges of the proposed DC-MSF sensor are 1.375–1.425 and −15 °C–95 °C, respectively.

Long-Period Fiber Grating Based on Side-Polished Optical Fiber and Its Sensing Application

Abstract: A novel side-polished long-period fiber grating (LPFG) sensor was proposed and experimentally validated. Side-polished can provide a stronger evanescent field than traditional grating and bring superior sensitivity. The greater the side-polished depth, the higher the refractive index (RI) sensitivity. When $d = 44\,\,\mu \text{m}$ , the RI sensitivity reached 466.85 nm/RIU in the range of 1.3330–1.3580, which is fourfold higher than the LPFG prepared by the electric-arc discharge (EAD) method. A graphene oxide (GO) nano-film is coated on the LPFG to make it realize high sensitivity relative humidity (RH) sensing. Humidity sensitivity reached −0.193 nm/%RH in the range of 40%–80% RH. In addition, side-polished breaks the symmetry of the distribution of the cross-sectional light field, which determines the ability to achieve vector curvature measurement. It shows good sensing performance in the same/opposite bending direction as the side polished surface. When the input light polarization is 90°, the average sensitivity reaches 5.03 and −5.9 nm/ $\text{m}^{-1}$ in the range of 0–19.67 $\text{m}^{-1}$ , respectively. This strongly indicates that the fabricated sensors show high sensitivity, low-cost materials, and robust performance and break the limitations of the EDA method to prepare gratings, which have good application potential for biomedicine and the field of construction.

Plastic Optical Fiber Enabled Smart Glove for Machine Learning-Based Gesture Recognition

Abstract: Gesture recognition has always been an important research direction in the field of human-computer interaction (HCI). In this paper, a wearable gesture recognition system based on D-shaped plastic optical fiber (POF) curvature sensor was proposed and experimentally studied. A highly bend sensitive D-shaped POF curvature sensor was made and integrated into a five-channel signal acquisition system on a PCB board (8×4.5 cm), which was embedded into an elastic glove to collect fingers' movement data. Thirteen gestures and eleven grasping actions were defined, and the gesture data, the grasping action data and the gesture data mixed with grasping action data were normalized, calibrated and imported into a support vector machine (SVM) classifier based on Gaussian kernel function and feedforward neural networks (FNN) respectively. The recognition accuracy based on SVM of 13 gestures and 11 grasping actions reached 99.8% and 97.7% respectively. The recognition accuracy of 13 kinds of gesture data mixed with 11 kinds of grasping action data based on Gaussian kernel function in SVM classification model and FNN were 98.9% and 99.4% respectively.

Novel layered double hydroxides for uranium removal: a review

Abstract: In recent years, due to the rapid development of China’s nuclear industry, the need for uranium has been expanding, while the environmental pollution of water caused by uranium is also receiving more and more attention. Laminated double hydroxide (LDH) is favored by researchers in water pollution removal due to its special layered structure, good adsorption performance, regeneration and easy recycling. The mechanism of adsorption of uranium by the new LDH is summarized, the preparation process and removal effect are introduced, the removal mechanism and influencing factors are analyzed, and on this basis, the future development and research of adsorbent materials are proposed.

Investigation of Multimode Self-Similar Pulse Compression in Tapered Photonic Crystal Fibers

Abstract: In this paper, we theoretically investigate the multimode self-similar pulse compression (MM-SSPC) in tapered photonic crystal fibers. To expand the self-similar theory beyond single-mode scenarios, we have discovered through analytical analysis that the width of the input pulse has a significant impact on perturbing the MM-SSPC process. We proceed to solve the multimode generalized nonlinear Schrödinger equation using numerical methods for various input pulse widths, which leads to the observation of three distinct types of multimode pulse compression. MM-SSPC only takes place when the input pulse width is comparatively longer. Our numerical results are consistent with the predictions of analytical calculations. Our results demonstrate that by using input pulses of 2.5 ps in duration, three modes can be compressed in a self-similar manner to 200 fs, which corresponds to a compression factor of 12.5. Finally, We establish the minimum input pulse width required to enable the MM-SSPC to function for the three specific modes of interest. Our findings provide an effective guidance to design pulse compressor for the generation of pedestal-free, high-energy femtosecond pulses.

A Sensor With Coating Pt/WO Powder With an Erbium-Doped Fiber Amplifier to Detect the Hydrogen Concentration

Abstract: A highly sensitive hydrogen sensor (HS) coated with Pt/WO3 powder with an erbium-doped fiber amplifier (EDFA) is proposed and experimentally demonstrated. The sensing head is constructed by splicing a short Section of tapered small-diameter coreless fiber (TSDCF diameter of 62.5 $\mu \text{m}$ and tapered to 14.5 $\mu \text{m}$ ) between two single-mode fibers (SMFs). The Pt/WO3 powder adheres to the surface of polydimethylsiloxane (PDMS) film coated on the TSDCF structure, which is sensitive to hydrogen. An EDFA is introduced into the sensor system to improve the quality factor ( ${Q}$ -factor) of the output spectrum and thus improve the sensor’s resolution. As the hydrogen concentration varies from 0% to 1.44%, the measured maximum light intensity variation and the sensor’s sensitivity are −32.41 dB and −21.25 dB/%, respectively. The sensor demonstrates good stability with the light intensity fluctuation of < 1.26 dB over a 30-min duration.

Rapid Detection of SARS-CoV-2 Nucleocapsid Protein by a Label-Free Biosensor Based on Optical Fiber Cylindrical Micro-Resonator

Abstract: The current global outbreak of coronavirus (COVID-19) continues to be a severe threat to human health. Rapid, low-cost, and accurate antigen detection methods are very important for disease diagnosis. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) nucleocapsid protein (N-Protein) is often used as the diagnostic and screening for coronavirus detection. To this end, we propose and experimentally validate a highly sensitive whispering gallery mode (WGM) optical cylindrical micro-resonator (CMR) for bioimmunoassay detection. To study the biokinetic process of immunoassay, the surface of the WGM micro-resonator is functionalized with N-Protein monoclonal antibody (N-Protein-mAb), which led to the specific detection of N-Proteins. The spectral characteristics of the WGM resonance dip were investigated, and it is found that the transmission spectrum of WGM shows a monotonically increasing red-shift as a function of recording time. The WGM red-shift is due to the antibody-antigen reaction and can be used for the analysis of the immunoassay process. The wavelength shift is shown to be proportional to the concentration of N-Protein, which ranges between 0.1 and 100 $\mu \text{g}$ /mL. Finally, different types of samples (concentration of $10~\mu \text{g}$ /mL of N-Protein) were prepared and tested to simulate the specificity of the sensor in the practical application environment. This method has the merits of a rapid assay, lower expense, easy preparation, and miniaturization, which makes the sensor have the potential for broad applications in the field of biochemistry and biomedical detection.

(3-Aminopropyl) triethoxysilane-based immobilization of Pt/WO3 on a microfiber sensor for high sensitivity hydrogen sensing

Abstract: A novel high stability hydrogen sensor based on a Pt/WO3 coated single-mode tapered-no-core single-mode (STNCS) fiber interferometer is proposed and experimentally studied. The STNCS structure is treated by (3-Aminopropyl) triethoxysilane (APTES) and then coated with Pt/WO3 nanorods. Compared to the traditional method of using poly (dimethylsiloxane) (PDMS) to adhere Pt/WO3 nanorods on the fiber surface, the APTES modified fiber forms strong covalent bonds with Pt/WO3 with stronger adhesion to the fiber surface, resulting in improved long-term stability. Experimental results show that the sensitivity of the sensor varies from -31.05 nm/% to -4.30 nm/% as the hydrogen concentration increases from 0 to 1.04%. The sensor also demonstrates good reproducibility, longer term stability and repeatability.

A Graphene Coated Micro-Channel Fiber Sensor Based on Localized Surface Plasmon Resonance

Abstract: In this paper, a novel localized surface plasmon resonance (LSPR)-based micro-channel photonic crystal fiber (PCF) sensor is proposed. The LSPR-PCF sensor is designed with the three micro-channels, and the metal nanostraps and graphene are coated onto the PCF as the sensing elements. To realize high refractive index (RI) sensitivity, the influence of different plasmon materials, structure parameters, and graphene layers on the sensing performance of the LSPR-PCF sensor is investigated. The maximum wavelength sensitivity and amplitude sensitivity of the optimized LSPR-PCF sensor are up to 45800 nm/RIU and 1818RIU −1 , respectively, when the RI changes from 1.35 to 1.42. Furthermore, the proposed LSPR-PCF sensor achieves the maximum figure of merit of 594.8, alone with a resolution of 2.18×10 −6 RIU. Because of its simple structure and excellent sensing performance, the proposed LSPR-PCF sensor has potential applications in biochemistry and environmental science.