Articles
Publication Date: 2025
Optics Express (10944087)33(3)pp. 4550-4562
All-optical switches (AOSs) with the unique functionality of light controlling by light are the essential components of advanced photonics. However, it is still a grand challenge to propose materials with appropriate nonlinear effects and structures with high-performance all-optical switching. This study proposes an AOS with a hybrid silica-azopolymer optical microfiber coupler configuration. This structure is characterized by in-line switching functionality, extremely high extinction ratio of 22 dB at λ = 1550 nm, low-insertion loss (<1 dB), and ease of fabrication process. It is shown that, because of the photo-induced birefringence in the azopolymer microfiber, the functionality of the introduced switch depends on the polarizations of the controlling and propagating light signals. Moreover, using full-wave electromagnetic simulations, the performance of the hybrid AOS is explained and clarified. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
Publication Date: 2024
IEEE Sensors Journal (1530437X)24(24)pp. 40994-41002
Optical microfiber couplers (OMCs) with simple structure, low loss, and high sensitivity have been broadly involved in physicochemical fiber sensing applications. Until now, the fabrication of OMCs using arc discharge as a fast, clean, and low-cost method has not been explored. In this study, an arc-discharge fiber heating and pulling process for OMC manufacturing is presented and the characteristics of the arc-induced structures are investigated. It is shown that, in addition to high spectral visibility and refractive index (RI) sensitivity, importantly, the arc-induced OMCs exhibit ultralow temperature dependency of less than 1.9 pm/°C, over the wide testing range of 15 °C to 315 °C. Finally, an exact theoretical explanation is presented for the observed different temperature coefficients using analytical expressions and full-wave simulations based on the modal analysis of OMCs. Thus, the introduced arc-discharge technique and the resultant OMCs with ultralow temperature dependency could be useful for real-world applications of microfiber (MF) couplers. © 2001-2012 IEEE.
Publication Date: 2024
Journal of Industrial and Engineering Chemistry (1226086X)130pp. 623-637
A new high-efficiency continuous photocatalytic system composed of a microreactor and an optical fiber coated with a ZnO nanorod array/TiO2/GO with a retention time of 4–7 min was introduced. Using a new step-by-step chemical bath deposition method, a ZnO nanorod array coated with TiO2 and GO was grown on the surface of an optical fiber with different mass ratios. The coated photocatalytic layer was characterized using XRD, XPS, Raman spectra, UV-drs, TEM, and SEM. The photocatalytic degradation efficiency of Cefixime (CEF) in the microreactor was studied under irradiation from two diffusing and focusing light sources to determine the effect of light radiation type on the efficiency. ZnO nanorods/TiO2 coated optical fiber (Ti/Zn weight ratio = 0.37) and GO deposition during the growth of ZnO nanorods demonstrated the highest degradation efficiency. The operational and geometrical parameters were optimized as fiber length = 15 cm, fiber diameter = 500 µm, CEF concentration = 10 ppm, and pH = 4.8. The removal efficiency under these conditions was approximately 67 % with a diffused light source and 80.1 % with a focused light source. The coated photocatalytic composite showed high stability to the liquid flow after 1200 min of continuous operation, indicating the ZnO nanorods/TiO2/GO coating method's success. © 2023 The Korean Society of Industrial and Engineering Chemistry
Publication Date: 2023
IEEE Sensors Journal (1530437X)23(14)pp. 15570-15577
With strong evanescent waves, optical microfibers (MFs) provide guided lights the ability to directly interact with surrounding environments, whereby several fiber optics chemical sensors have been realized. In this study, based on MFs external refractive index (RI) sensitivity, a multimode optical fiber (MMF) specklegram RI sensor with MMF-MF-MMF configuration is presented. As the MF Section is exposed to the liquids of different RIs (in the range of 1.333-1.368), the interaction between the liquids and evanescent waves modulates the guidance status of the MF, thereby changes the excited modes within the end MMF Section and affects the output speckle pattern accordingly. The evaluation of the functionalities of the MFs with different waist diameters (11, 18, 33, and 42 μ m ) shows that the MF with 33- μ m waist diameter results in the highest output specklegram RI sensitivity, which has been quantified by the zero-mean normalized cross correlation coefficient (ZNCC). Moreover, the response time and sensitivity of the proposed fiber specklegram sensor (FSS) have been simultaneously improved by applying spacial filter on the captured speckles. The RI sensor has also been studied for the temperature detection and showed 0.013°C-1 linear sensitivity within the range of 25 °C-65 °C. Finally, the theoretical analysis of the supported modes by the MFs of the specified waist diameters verifies that 33- μ m sample with high number of guided modes and strong total evanescent waves is the optimum case for the MMF-MF-MMF specklegram RI sensor. © 2001-2012 IEEE.
Publication Date: 2022
Journal of Lightwave Technology (15582213)40(24)pp. 7930-7936
Optical microfiber long period gratings (MLPGs) with advantages such as low insertion loss, polarization independence, high resonance dip, and simple configuration are broadly involved in different applications, including fiber optics micro-scale components and sensors. However, it is still a grand challenge to fabricate MLPGs by using current long-time multistep processes. Herein, based on the typical arc-discharge fiber heating and pulling technique, a very fast single-step process for MLPGs fabrication is presented. In this process, the applied fiber heating arc-discharge is functionalized by a series of narrow OFF-pulses to simultaneously modulate the being pulled microfibers. Through the developed one-step technique, a low-loss adiabatic optical microfiber with a periodic array of micro-tapers along its waist region is implemented in less than 100 s, which is much faster than current methods. It is shown that the realized single-step MLPGs with the diameter of 20 μm are characterized by high resonance dip (>27 dB), low transmission loss (≤1.2 ± 0.2 dB), narrow FWHM (<20 nm), and high repeatability. The measured external refractive index (RI) sensitivity and temperature dependency of the gratings are 744 nm/RI-unit and 12 pm/°C, respectively. The results of this study could be of interest for the applications of the MLPGs for miniature fiber optics elements and sensors realization. © 1983-2012 IEEE.
