Fiber Taper Research Articles

Experimental demonstration of mode-matching and Sagnac effect in a millimeter-scale wedged resonator gyroscope

The highly efficient coupling of light from conventional optical components to optical mode volumes lies in the heart of chip-based micro-devices, which is determined by the mode-matching between propagation constants of fiber taper and the whispering-gallery-mode (WGM) of the resonator. Optical gyroscopes, typically realized as fiber-optic gyroscopes and ring-laser gyroscopes, have been the mainstay in diverse applications such as positioning and inertial sensing. Here, the mode-matching is theoretically analyzed and experimentally verified. We observe the Sagnac effect in a millimeter-scale wedged resonator gyroscope, which has attracted considerable attention and has been rapidly promoted in recent years. We demonstrate a bidirectional pump and probe scheme, which directly measures the frequency beat caused by the Sagnac effect. We establish the linear response between the detected beat frequency and the rotation velocity. The clockwise and counterclockwise rotation can also be distinguished according to the value of the frequency beat. The experimental results verify the feasibility of developing the gyroscope in a WGM resonator system and pave the way for future development.

Medial Ulnar Collateral Ligament Injuries in Contact Athletes.

The purpose of this article is to review medial ulnar collateral ligament (UCL) injuries in contact athletes. UCL injuries in overhead throwing athletes are typically chronic attenuation due to repetitive valgus stress on the elbow during the throwing motion. As such, UCL reconstruction is commonly performed for these athletes. In contrast, UCL injuries in contact athletes are usually acute ligament tears or avulsions of a ligament with otherwise normal tissue. Nonoperative treatment is typically the first-line treatment for partial injuries. UCL repair may work well for acute complete injuries and may avoid the donor site morbidity of UCL reconstruction. Most of the literature regarding UCL injuries have been performed in baseball players. Historically, UCL repair has had poor outcomes in baseball players due to the chronic ligament attenuation. Therefore, much of the recent literature has focused on outcomes of UCL reconstruction, which are generally excellent. However, there is a paucity of literature studying outcomes of UCL injuries in contact athletes and those studying UCL repair. One recent study looked at a new technique for UCL repair with collagen-coated fiber tape augmentation in baseball players and found good short-term outcomes. UCL injuries in contact athletes occur typically as acute tears or avulsions. While UCL reconstruction has typically been recommended as the accepted treatment for UCL tears that require operative treatment, UCL repair may be a good alternative in contact athletes.

A novel heterogeneous-particle model based on peridynamics for flexural mechanical properties of randomly oriented fiber reinforced composites

On the basis of peridynamic (PD) theory, a heterogeneous-particle model is proposed to investigate the flexural mechanical properties of a chopped carbon fiber tape reinforced thermoplastic (CTT). In contrast to the numerical analysis on the tensile behavior, the simulation of flexural behavior of CTT is challenging because a full-scale model rather than a representative volume element (RVE) is required in the modeling. The novelty is that the mesoscopic structure, such as the random orientation of fibers and the thickness of tapes, are represented in the simulation of flexural mechanical behavior. This model successfully simulates the flexural fracture morphologies, well predicts the flexural mechanical properties, and effectively captures the characteristic of the scatter in flexural properties. The effects of tape thickness, fiber orientation, support span and specimen thickness on the flexural behavior of CTT are investigated by this model. The influencing mechanism of these factors is revealed through this model.

Evaluation and Modeling of Tensile Properties of Chopped Carbon Fiber Tapes Reinforced Thermoplastics of Different Tape Thicknesses

Evaluation and Modeling of Tensile Properties of Chopped Carbon Fiber Tapes Reinforced Thermoplastics of Different Tape Thicknesses

High Sensitivity Fiber Interferometric Strain Sensors Based on Elongated Fiber Abrupt Tapers.

We demonstrate high-sensitivity fiber strain sensors based on an elongated abrupt taper. The fiber abrupt taper, with a tapered diameter ranging from 40–60 μm, was made by using a hydrogen microflame to break the waveguide adiabaticity so as to convert the fundamental mode into cladding modes. The abrupt taper was further uniformly tapered by using a normal moving flame with a torch diameter of 7 mm to elongate the tapered region until the tapered diameter was down to 2.5–5 μm. The excited high-order modes were confined to propagate along the cladding and then recombined at the rear edge of the fiber taper to produce interferences with extinction ratios of up to 16 dB. The tapered region was pulled outwardly to change the optical path difference (OPD) between modes to measure the tensile strain with all the interfering wavelengths blue-shifted. The measured best strain sensitivity was 116.21 pm/με and the coefficient of determination R2 of linear fitting exhibits high linearity. This strain sensor based on elongated abrupt taper is several times higher than that of most of the fiber strain sensors ever reported.

Fabrication of low-loss adiabatic optical microfibers using an attainable arc-discharge fiber tapering setup

Based on an attainable cost-effective homemade arc-discharge fiber heating and pulling setup, a fast and highly controllable process for fabricating low-loss adiabatic optical microfibers (AMFs) is presented. For this purpose, two linear translation stages driven at the same direction with different speeds stretch and shift a silica fiber through a heating arc-discharge zone induced between two tungsten electrodes. In this process, the amplitude of the inducing arc voltage and the relative positions of the electrodes and the tapering fiber adjust the characteristics of the heating zone. This technique is relatively fast and takes only about 55 s to form a low-loss (<0.2 dB) AMF. By this setup, the fabricated microfiber samples with the input and output transitions of about 12 mm lengths and the waists diameters of 3, 5, and 8μm exhibit very low insertion losses of 0.16, 0.13, and 0.07 dB, respectively. The adiabaticity of the resultant microfibers is experimentally examined by monitoring their spectral responses and is theoretically investigated based on fiber tapers adiabaticity criteria. Finally, as an important application of the microfibers, two knot resonator configurations are manually implemented on the 5μm AMFs, and their external sensitivities are investigated using the ethanol/water solutions of different concentrations. This study shows the functionality of an affordable arc-discharge setup and appropriate process for fabricating high-performance AMFs, which could be useful for their future applications.

Quantum-Enhanced Fiber Curvature Sensor Exploiting Intensity-Correlated Pulse Twin Beams

A quantum-enhanced fiber curvature sensor based on single-mode fiber (SMF) taper exploiting intensity-correlated pulse twin beams has been proposed and experimentally realized. The curvature can be measured by intensity difference noise power and degree of intensity difference squeezing which are tailored by the bending-induced loss of one beam’s SMF taper. In addition, the three different waist diameters of SMF tapers, i. e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$52.12~ \boldsymbol {\mu }\text{m}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$61.68~ \boldsymbol {\mu }\text{m}$ </tex-math></inline-formula> , and 67.54 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\mu }\text{m}$ </tex-math></inline-formula> respectively have been prepared using a fusion splicer. Finally, the maximum measured sensitivity enhancement of 4.42 dB/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and signal-to-noise ratio enhancement of 2.0 dB have been experimentally implemented through intensity difference measurement technique compared with the corresponding classical counterpart (double-channel light source). In contrast to other curvature sensors, this proposal has the advantages of high sensitivity, ease of fabrication, simple structure, and low cost.

Peak wavelength and bandwidth tunable fiber Bragg grating notch filter induced by femtosecond laser point by point inscription

In this work we present a novel fiber wavelength notch filter induced by femtosecond laser point-by-point technique. The filter consists of a pair of slightly shifted grating inscribed around a fiber taper. Such a structure offers similar properties as that of phase shifted Bragg grating, but with more facile fabrication process. More interestingly, simultaneous modulation of peak position and bandwidth can be easily realized. The proposed fiber notch filter may find applications in the areas of multi-parameter sensing and tunable fiber lasing.

Experimental and numerical study on a new floor heating system using carbon fiber tape embedded in cement mortar

A new design for a floor electrical heating system manufactured with commercially available carbon fiber tape (CFT) as heating source embedded in cement mortar is proposed in this study. The characterization on thermal performance of the system was then performed to analyze the heating efficiency, temperature change with spatial and temporal variations, and energy consumption. The experimental results showed that the temperature of the CFT surface could increase at a rate of 1.83 °C/min through the heating system, and the heating flux is 16.31W/m2. Numerical analysis was also conducted on the heating panel and its associated heating system. The temperature gradient in the vertical direction is much greater than that in the horizontal direction. The heating power of the CFT is stable at a constant voltage, and the reflective film and insulation board effectively minimize the heat transfer towards the bottom of the device, thus enhancing the heating efficiency. The automatic temperature control device can also decrease energy consumption. The temperature increase and power-on time of the device are affected by the ambient temperature. The temperature change and distribution obtained by FE thermal analysis are in good agreement with the experimental results. Finally, the number and spacing of CFT are optimized to improve the performance of the heating system, and more uniform temperature distribution can be achieved using more CFTs with the same power consumption.

Single system for online monitoring and inspection of automated fiber placement with object segmentation by artificial neural networks

The reduction of material defects in the automated fiber placement process is one of the significant factors for manufacturing large and complex components more efficiently in the future. However, the monitoring of complex manufacturing processes usually requires complex sensor and computer systems that are often quite sensitive to disturbances and errors. New techniques such as image segmentation with neural networks provide a new approach to this problem and have the potential to solve complex processes faster and more robustly. In this study, a system is presented that performs monitoring, inspection and measurement tasks simultaneously in automated fiber placement processes. The system is based on the SiamMask network which is used for the automatic image processing. The artificial neural network is trained to recognize individual carbon fiber tapes and segment them for additional analysis. For the creation of the testing- and training data, an analytical approach is presented. The post-processing of the object segmentation, which is the primary output of the SiamMask network and the identification of individual tapes, provides accurate measurements which are demonstrated by an example. We show that image segmentation with modern approaches like SiamMask offers great potential to handle highly complex engineering tasks in a faster and more intelligent manner in comparison to conventional methods.

НЕКОТОРЫЕ СПОСОБЫ УСИЛЕНИЯ ФУНДАМЕНТНЫХ ПЛИТ

Various ways of strengthening foundation slabs are analyzed in relation to cases when, after the construction of foundation slabs, as a result of project adjustments, the load on them increases. An example of the implementation of the reinforcement of the foundation plate in the case of an increase in the number of storeys of the building from 10-14 floors to 17 is given. The effectiveness of various ways of strengthening foundation slabs is investigated by the example of the regional children’s clinical hospital under construction in Tver. The methods of reinforcement of foundation slabs are conditionally divided into two groups within the framework of constructing a finite element computational model. The first group includes methods that compensate for the lack of upper stretched reinforcement of the foundation plate by sticking on the surface of problem areas of steel or carbon fiber tapes. The second group includes a method that redistributes bending forces in the foundation plate from more loaded to less loaded sections. Methods of modeling of sub-columns in the computing environment of the LIRA-CAD software complex are investigated

Quasi-Distributed Refractive Index Sensing by Stimulated Brillouin Scattering in Tapered Optical Fibers

In this paper, we demonstrate that multiple tapers in optical fibers allow for quasi-distributed refractive index sensing via a high spatial resolution Brillouin Optical Frequency-Domain Analysis (BOFDA) configuration. We first characterize, theoretically and experimentally, the variation of the Brillouin frequency shift (BFS) with the diameter of the tapered fiber. Then, we characterize the dependence of the BFS from the outer refractive index in an optical fiber taper with a waist diameter of 10 &#x00B5;m. Finally, we show that more tapers can be realized along the same fiber, in order to provide multi-point refractive index sensing.

Automated in situ consolidation process for pre-impregnated carbon fibers: a cyber phisycal approach

The concept known as the fourth industrial revolution (Industry 4.0) has developed a wide field of study, such as the Internet of Things (IoT), Cyber-Physical Systems (CPS) and Information and Communication Technology (ICT), with the objective to achieve enhancing the processes performance of automated systems. This work focuses on the field of CPS for an in situ consolidation machine, which handles pre-impregnated, in this case unidirectional carbon fiber tapes with polyamide 6, in order to create composite laminates. The physical model involves an unwinding system that feeds the tape into a turning table through a pressing mechanism, which has a radiation heater before and refrigeration after the presser to guarantee the composite temperature. The objective is to model and simulate the heating process before, during and after the pressing mechanism to feed an optimization algorithm in order to calculate the optimal working parameters such as heaters power, heater positioning and process speed taking into account the temperatures of the tape, to avoid overheating and to improve process time. The results are processed, so that they can send and receive data constantly, to an optimization system to alter parameters, without making programing code changes and avoiding the need to stop the consolidation. The CPS can handle different classes of pre-impregnated composites, by learning during the consolidation process, in order to improve the overall result, without the need of fully or partially reprograming the code, which a main characteristic of CPS.

Design of the scintillator imaging lens for the neutron imaging system at the 100 kJ-level laser facility.

Deuterium-tritium neutron yield has reached up to about 1013 at the 100 kJ-level laser facility, which makes measurement of neutron emission images possible with the neutron imaging system. There are two methods to collect neutron images from the scintillator array, optical fiber taper and the lens system. Here, we report a design of the lens system for the neutron imaging system at the 100 kJ-level laser facility. The lens system, which consists of a nine-element collecting lens, with a spatial resolution of 20 µm and a light-collection efficiency of 5.9% has been designed.

Analysis of Fiber Orientation and a Simulation of Damage Fracture Prediction Using an X-ray Phase Imaging Method for Discontinuous Carbon Fiber Random Laminated Molded Products

In chopped carbon fiber tape reinforced thermoplastic（CTT）material, the anisotropic region of fiber orientation after press molding often causes the degradation of mechanical properties and damage and fracture. This study explores means of obtaining the fiber shape and fiber orientation tensors from molded products and then predicting the CTT mechanical properties and damage fracture locations. Extensive fiber shape data obtained by X-ray CT image processing are analyzed using a simple method to create a fiber waviness model.The fiber orientation tensor of the molded product is obtained through X-ray phase imaging. The material properties of a finite element model with CTT are calculated and mapped from the fiber waviness model and orientation tensor, and damage fracture prediction is simulated. Results showed that the fracture positions of both the test and simulation agreed in specimens having large anisotropic regions. However, the specimens with small anisotropic regions did not match. Therefore, the images of strain distribution of the test piece under a tensile load were compared by cross-correlation. Results showed a large correlation between the tensile test and simulation results, thus confirmed the effectiveness of the simulation.

Near-Field Modulation of Differently Oriented Single Photon Emitters with A Plasmonic Probe.

Single photon emitters (SPEs) are critical components of photon-based quantum technology. Recently, the interaction between surface plasmons and emitters has attracted increasing attention because of its potential to improve the quality of single-photon sources through stronger light-matter interactions. In this work, we use a hybrid plasmonic probe composed of a fiber taper and silver nanowire to controllably modulate the radiation properties of SPEs with differently oriented polarization. For out-of-plane oriented SPEs such as single CdSe quantum dots, the radiation lifetime could be reduced by a factor as large as seven; for in-plane oriented SPEs such as hBN defect SPEs, the average modulation amplitude varied from 0.69 to 1.23, depending on the position of the probe. The experimental results were highly consistent with the simulations and theory. This work provides an efficient approach for optimizing the properties of SPEs for quantum photonic integration.

An ultra-sensitive gas pressure sensor based on tapered fiber coated with PDMS film working at TAP

An ultra-sensitive gas pressure sensor based on tapered single-mode fiber (SMF) coated with thin polydimethylsiloxane (PDMS) film which works at turning around point (TAP) is proposed and demonstrated. Ascribing to the high refractive index of PDMS, the tapered SMF covered with PDMS can work at TAP with larger taper diameter, which effectively enhance the structural strength and stability. At the same time, the porous character of PDMS film makes the interferometer have ultrahigh gas pressure sensitivity. By using spin-processing method, the thickness of the PDMS film covering the fiber taper can reach only the order of micron, so that the pressure recovery time of the sensor is as short as 20 s. Experimental results show that the gas pressure sensitivity of the proposed sensor can be as high as −159.80 nm/MPa in the range from 1 KPa to 100 KPa, and another dip away from the TAP obtains the sensitivity of −69.61 nm/MPa.

Formation mechanism of blemishes in a fiber-optic imaging element.

A rigid fiber-optic imaging element with high fidelity, high resolution, and high contrast is applied in low-level-light night vision and particle detection devices. Any optical fiber in elements is an image transmission unit. However, the independence and integrity of image transmission are disturbed constantly, resulting in blemishes. This paper studies the formation mechanism of the blemishes of rigid fiber-optic imaging elements. The existence of defects with different sizes in or among the optical fibers, and fiber deformation decreasing light transmission ability are simulated theoretically. Then experiments are carried out to verify the simulation results. It is theoretically concluded that a blemish forms when the equivalent sphere radius (RES) of a stone defect is greater than 1.2 µm in a normal fiber, and 1.1 µm in a taper fiber. The RES of a bubble defect is greater than 1.3 µm in the fiber, which can form blemishes. Excessive deformation of fibers behaving as a clad layer with thickness less than 0.3 µm also results in the formation of blemishes. When fiber deformation and the existence of stone are considered, blemishes can occur as long as the size of the stone defect among the fibers is greater than 0.823 µm. The results provide data support and theoretical guidance in solving blemishes and other fixed pattern noises, and significantly improve the engineering and application level of fiber-optic imaging elements.

Metal-Free Fixation for Free Bone-Block Reconstruction of Chronic Anteroinferior Shoulder Instability

Background: Anterior shoulder instability is common and may cause a considerable effect on quality of life. For cases with glenoid bone loss, there is still a controversial discussion regarding the optimal treatment. Most of the recent methods are using metal implants to attach the needed graft to the glenoid with reported disadvantages such as metal impingement, damage to the humeral head, cartilage destruction, and premature arthritis. Indications: (1) Erosion-type defects with significant bone loss (&gt;15%-20%); (2) chronic fragment-type defects if the size of the fragment is not large enough for an anatomical reconstruction; and (3) non-reconstructible, multifragmented acute fragment type of lesions. Technique Description: After placing the patient in a lateral decubitus position and fixing the arm in a traction devise, 3 arthroscopic entries are established: a posterior portal, an anterosuperior portal, and an anteroinferior portal. A harvested tricortical iliac crest bone graft is provided with 2 drilling holes which match the drilling holes through the glenoid. The tapes are then placed from the posterior to the anterior side of the glenoid, and then the graft is passed from the anterior to the posterior side, thus compressing the cancellous side of the bone block onto the glenoid defect. A following interconnection of the sutures creates a continuous loop. The end of the tapes was loaded into a pretied racking hitch knot system, which creates sliding knots between the 2 pair of tapes, whereon the knots can be reduced to the glenoid in a symmetrical fashion. Finally, the reconstruction of the anterosuperior labrum can be done, to cover the bone block with enough soft tissue. Results: First short-term results show radiographic consolidation after 3 months and an increased median glenoid estimated surface area at 12 months. The functional scores showed good outcomes, and there were no serious complications reported. Discussion/Conclusion: The presented arthroscopic reconstruction of the glenoid using a tricortical bone graft and high-strength fiber tapes provides a metal-free technique which results in a high primary stability of the construct and should therefore be considered when treating anterior shoulder instability with significant bone loss.

Taper-assisted coupling between two optical cavities at exceptional point and bound state in the continuum

Long-distance coupling between two optical cavities is enabled through a taper fiber. Phase shift and loss induced by the taper lead to complex coupling strength and hence observation of various distinctive coupling conditions like exceptional points, bound state in the continuum, and dissipative coupling with optothermal effect. Large tunability of coupling conditions is demonstrated via controlling the translation stage, as manifested in the transmission spectrum. Theoretical prediction and simulation coincide well with experimental measurement. Lastly, we propose to advance the role of taper for application in taper-based sensing and optomechanics.