Showing papers on "Hard-clad silica optical fiber published in 2018"

Graphene/Au-Enhanced Plastic Clad Silica Fiber Optic Surface Plasmon Resonance Sensor

Abstract: Owing to its large surface-to-volume ratio and good biocompatibility, graphene has been identified as a highly promising candidate as the sensing layer for fiber optic sensors. In this paper, a graphene/Au-enhanced plastic clad silica (PCS) fiber optic surface plasmon resonance (SPR) sensor is presented. A sheet of graphene is employed as a sensing layer coated around the Au film on the PCS fiber surface. The PCS fiber is chosen to overcome the shortcomings of the structured microfibers and construct a more stable and reliable device. It is demonstrated that the introduction of graphene can enhance the intensity of the confined electric field surrounding the sensing layer, which results in a stronger light-matter interaction and thereby the improved sensitivity. The sensitivity of graphene-based fiber optic SPR sensor exhibits more than two times larger than that of the conventional gold film SPR fiber optic sensor. Furthermore, the dynamic response analyses reveal that the graphene/Au fiber optic SPR sensor exhibits a fast response (5 s response time) and excellent reusability (3.5% fluctuation) to the protein biomolecules. Such a graphene/Au fiber optic SPR sensor with high sensitivity and fast response shows a great promise for the future biochemical application.

Twisting-Rate-Controlled 125 μm Cladding Randomly Coupled Single-Mode 12-Core Fiber

Abstract: A multicore fiber design with more than 10 coupled cores is investigated numerically and experimentally. It is revealed that a randomly coupled 12-core structure with a square lattice core arrangement can be realized within a 125 μm cladding by employing fiber twisting of more than a few π rad/m. A 125 μm-clad twisting-rate-controlled 12-core fiber is then fabricated and a relative core density of 12 compared with conventional single-mode fiber is achieved while maintaining a low spatial mode dispersion characteristic of 8.4 ps/√km at 1550 nm. Finally, we experimentally evaluated the performance of 12 spatial channels by conducting a 24 × 24 MIMO transmission experiment.

Laser Cladding-Based Metallic Embedding Technique for Fiber Optic Sensors

Abstract: In many applications in the industry, securely attaching fiber optic sensors to metallic structures is important for optimum monitoring, overcoming the limitations of glues and adhesives which are known to degrade under certain circumstances. To avoid that problem, creating a metallic bond to attach the sensors securely to the metal surface is important. Commercial fiber optics with metal coatings can be used but it is important not to damage the sensor itself which is written in the thin optical fiber. In this work, an alternative laser cladding technology has been studied for embedding metal-coated fiber optics into which fiber Bragg grating (FBG) sensors have been written. A three-step strategy was selected for embedding the metal coating fibers to create the best conditions to allow high-quality measurements. This has been seen to allow good control of the embedding process to be achieved and to minimize the thermal and mechanical stress generated. The research undetaken has shown that it is possible to embed Cu- and Ni-coated fiber optics containing sensors to over 300 μ m with low losses, of between 0–1.5 dB (or 0–30%) and yet still enable satisfactory strain and temperature measurement results to be obtained. The research has shown that both Ni- and Cu-coated FBG-based fiber optic sensors could be embedded successfully and shown to give good mechanical and thermal response to similar nonembedded sensors and excellent cross-comparison with the conventional gauge used for calibration. The results are, therefore, particularly encouraging for the use of sensors of this type when incorporated to create metallic “smart structures” achieving durability of the sensors through the use of this innovative technique.

Compact Single-Mode Nd-Doped Silicate Glass Multitrench Fiber With 40 μm Core Diameter

Abstract: We report a 40 μm core-diameter single-mode multitrench fiber (MTF) based on Nd-doped silicate glass. Both the delocalization effect and leaky nature were considered in the design of the MTF. The silicate MTF was designed and fabricated using the rod-in-tube method. A maximum laser output power of ∼8.4 W with a slope efficiency of 54% was obtained from a 10-cm-long single-mode MTF.

Disilicate Dental Ceramic Surface Preparation by 1070 nm Fiber Laser: Thermal and Ultrastructural Analysis.

Abstract: Lithium disilicate dental ceramic bonding, realized by using different resins, is strictly dependent on micro-mechanical retention and chemical adhesion. The aim of this in vitro study was to investigate the capability of a 1070 nm fiber laser for their surface treatment. Samples were irradiated by a pulsed fiber laser at 1070 nm with different parameters (peak power of 5, 7.5 and 10 kW, repetition rate (RR) 20 kHz, speed of 10 and 50 mm/s, and total energy density from 1.3 to 27 kW/cm2) and the thermal elevation during the experiment was recorded by a fiber Bragg grating (FBG) temperature sensor. Subsequently, the surface modifications were analyzed by optical microscope, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS). With a peak power of 5 kW, RR of 20 kHz, and speed of 50 mm/s, the microscopic observation of the irradiated surface showed increased roughness with small areas of melting and carbonization. EDS analysis revealed that, with these parameters, there are no evident differences between laser-processed samples and controls. Thermal elevation during laser irradiation ranged between 5 °C and 9 °C. A 1070 nm fiber laser can be considered as a good device to increase the adhesion of lithium disilicate ceramics when optimum parameters are considered.

Micro-structured fibers and their applications in fiber-optic sensors and random fiber lasers

Abstract: Micro-structured fibers are important devices that have drawn intensive attentions and proved to be powerful platforms for various applications over the past decades due to their remarkable merits ...