Fiber Splicing Research Articles

Tapered Fiber-Optic Mach-Zehnder Interferometer for Ultra-High Sensitivity Measurement of Refractive Index.

A Mach-Zehnder interferometer (MZI) based fiberoptic refractive index (RI) sensor is constructed by uniformly tapering standard single mode fiber (SMF) for RI measurement. A custom flame-based tapering machine is used to fabricate microfiber MZI sensors directly from SMFs. The fabricated MZI device does not require any splicing of fibers and shows excellent RI sensitivity. The sensor with a cladding diameter of 35.5 µm and length of 20 mm exhibits RI sensitivity of 415 nm/RIU for RI range of 1.332 to 1.384, 1103 nm/RIU for RI range of 1.384 to 1.4204 and 4234 nm/RIU for RI range of 1.4204 to 1.4408, respectively. The sensor reveals a temperature sensitivity of 0.0097 nm/°C, which is relatively low in comparison to its ultra-high RI sensitivity. The proposed inexpensive and highly sensitive optical fiber RI sensors have numerous applications in chemical and biochemical sensing fields.

Ring Architecture Analysis Implementation by Using Fiber Network Survivability Techniques

In Optical Communication Network, the Central Officers (CO) can potentially be connected by a ring. The CO’s on the ring are predetermined Hence in this paper the fiber network ring architecture analysis option determines a proto type software for the planning and designing of survivable networks. In this by using simulation package which is used to design survivable Diverse Protection (DP) technique(s). It includes the notes, links, connectivity, topology cost and multiyear point-to-point demands of the networks. It also consists of topology costs include fiber material and splicing, route mileage and regenerator threshold by using demands (circuits) from DS0 to DS3. Finally achieve the Multiperiod Ring Network Assortment Algorithm (MRNAA), Ring Selection Algorithm (RSA) through a Ring Routing Algorithm (RRA). In this the optical network can be enhanced further by means of protection and as well as providing a protection scheme towards a central office failure. It can be implemented by fiber spans from ring node source and detection. Further the Ring Architecture assures the survivable transport through the channel management from single direction self-survivability to multi direction self-survivability techniques.

Custom fabrication and mode-locked operation of a femtosecond fiber laser for multiphoton microscopy

Solid-state femtosecond lasers have stimulated the broad adoption of multiphoton microscopy in the modern laboratory. However, these devices remain costly. Fiber lasers offer promise as a means to inexpensively produce ultrashort pulses of light suitable for nonlinear microscopy in compact, robust and portable devices. Although encouraging, the initial methods reported in the biomedical engineering community to construct home-built femtosecond fiber laser systems overlooked fundamental aspects that compromised performance and misrepresented the significant financial and intellectual investments required to build these devices. Here, we present a practical protocol to fabricate an all-normal-dispersion ytterbium (Yb)-doped femtosecond fiber laser oscillator using commercially-available parts (plus standard optical components and extra-cavity accessories) as well as basic fiber splicing and laser pulse characterization equipment. We also provide a synthesis of established protocols in the laser physics community, but often overlooked in other fields, to verify true versus seemingly (partial or noise-like) mode-locked performance. The approaches described here make custom fabrication of femtosecond fiber lasers more accessible to a wide range of investigators and better represent the investments required for the proper laser design, fabrication and operation.

Highly-sensitive phase-interrogated RI sensor based on twin-core fiber with inherent noise suppression

In this work, we propose a highly-sensitive phase-interrogated RI sensor based on twin-core fiber with inherent noise suppression. This is the first time that optical fiber sensing structure is combined with digital holography technology, which works as the phase interrogation method, for measuring environmental parameters. The proposed system consists of a Mach–Zehnder interferometer formed by interference between the reference Gauss beam and the sensing dual-beam from the twin-core fiber (TCF). In the sensing optical path, a non-core fiber (NCF) and TCF offset splicing structure works as the differential fluid RI sensing element, which provides the capability of suppressing background signal by calculating the phase difference between the two cores of the TCF. This simple and practical phase subtraction method realizes direct background subtraction within a single measurement and reduces the background signal to 1/25 of the original noise level. The fluid is continuously introduced into a fluid tube in which the sensing fiber is installed to realize in-line measurement of fluid RI. Experimental results show that a short response time of about 13 s and a high sensitivity of about 835 rad/refractive index unit (RIU) are obtained. The high sensitivity benefits from direct interaction between light path and fluid, which is about 47 times higher than the sensitivity of a refractive index plasmonic sensor realized by enabling its quadrupole resonance in phase interrogation (17.46 rad/RIU). This scheme will find many applications in little sample consumption and high sensitivity required analytical measurement owing to its merits of high sensitivity, little sample consumption, fast response, and inherent background noise suppression.

Sensitivity-Enhanced Strain Sensor Based on Thin-Core Fiber Modal Interferometer Interacted With Tilted Fiber Bragg Grating

A sensitivity-enhanced strain sensor constructed by a 7-mm-long thin-core fiber (TCF) splicing with a 10-mm-long tilted fiber Bragg grating (TFBG) was proposed. The modal interferometer formed by the TCF will interact with the spectrum of the TFBG to form an overlapped spectrum, which will extremely increase the axial strain sensitivity of the TFBG. Experimental results showed that the wavelength shifts of the resonant dip in the overlapped spectra for the applied axial strain have a high sensitivity of 0.67 pm/ $\mu \varepsilon $ . Meanwhile, the proposed sensor has the temperature self-compensation function for the variation of the external temperature simply by measuring the relative wavelength shifts of the Bragg mode of the TFBG.

Polymer optical bridges for efficient splicing of optical fibers

We present an application of optonumerical methodology for improvement of functional parameters of polymer optical bridges that connect two optical fibers. To fully determine and improve the properties of this kind of microstructure, experimental methods are combined with numerical modeling. The parameters describing the functionality of the polymer optical bridges are optical losses (insertion and return), which determine the usability of those elements as optical fiber splices. These parameters are the function of such features as refractive index distribution, microstructure geometry, and propagation of the light wavelength. To analyze the relation of those features on the functional parameters of the studied microstructures, the experimental results are compared to the ones obtained with simulations. Numerical modeling of the aforementioned optical bridges is performed by means of the finite-difference time-domain method. Experimental methods consist of optical diffraction tomography, which is used to obtain a full three-dimensional refractive index distribution of optical bridge, and measurement of optical losses. Implementation of the proposed methodology in iterative procedure allows the optimization of the fabrication procedure to produce efficient and reliable optical splices with desired functional parameters—insertion loss at the level of 0.2 dB and return loss above 60 dB.

Multiparameter miniature fiber-optic sensor: design and signal interrogation

Miniature, all-silica, fiber-optic sensors capable of independent measurement of at least two different parameters are presented. Sensors were produced by a micromachining process based on the selective etching of specially designed phosphorousdoped optical fibers and an assembly-procedure that included fiber cleaving, fiber splicing and etching of fiber-micro-assemblies. Furthermore, an efficient method for independent readout of parameters in sensors that are composed of multiple resonators was also developed. The method utilizes a discrete Furrier transform of sensor’s optical spectrum and allows for simultaneous, crosstalk-free and highly sensitive readout of individual resonators’ path length changes.

Self-Filtering High-Resolution Dual-Sapphire-Fiber-Based High-Temperature Sensor

We present a self-filtering and high-resolution sapphire fiber sensor based on an extrinsic Fabry-Pérot interferometer for high-temperature sensing. The sensor has a high fringe visibility and signal-to-noise ratio. Two well-polished sapphire fibers are aligned side by side to realize shunting transmission between the background light and the interference signal. Heterogeneous fiber splicing between the sapphire fiber and the multimode silica fiber is realized for long-distance transmission of signals. A C-plane double-sided polished sapphire wafer is mounted perpendicularly to the tip of sapphire fibers as the Fabry-Pérot cavity. The crosstalk noise from input light caused by heterogeneous fiber splicing and fiber tip reflection is filtered out to reach a higher signal quality. A series of comparison experiments from 100 to 1080 °C were carried out for the difference in characteristics between self-filtering sensors and traditional sapphire fiber Fabry-Pérot sensors. The self-filtering sensor's fringe visibility was above 43.96%, and its signal-to-noise ratio was above 20.14 dB. The temperature resolution of the self-filtering sensor was better than 0.25 °C.

Release of Respirable Fibrous Dust from Carbon Fibers Due to Splitting along the Fiber Axis

ABSTRACT The aim of this report is to sensitize to the fact that some types of carbon fibers can split along the fiber axis during machining processes, thus becoming a source of respirable fibrous fragments in high concentrations. The risk of releasing respirable fiber dust must be assessed both in terms of carbon fiber materials and handling processes. We present an analysis of fiber concentrations released during mechanical processing of carbon fiber reinforced polymers at two different workplaces together with measurements from abrasion testing in a closed laboratory setup with inherent bulk sample analysis. During workplace measurements of the machining of polymer composites that were reinforced with pitch-based carbon fibers, concentrations of 830,000 WHO-fiber m–3 were observed 15 cm from the source and of 33,000 WHO-fiber m–3 at about 3 m distance. An explanation for such a high release propensity for respirable fibers with diameters below 3 µm is a fiber splitting along the axis of the studied fiber type. Comparative abrasion experiments of pitch and polyacrylonitrile-based carbon fiber reinforced polymer composites revealed that their fracture behavior differs from another. The studied polyacrylonitrile-based carbon fibers broke primarily perpendicular to their axis, whereas the studied pitch-based carbon fibers show fiber splicing and splitting along the fiber axis. In order to predict and manage health risks of the large variety of existing carbon fiber materials, the understanding of the relation between fiber microstructure, fracture morphology and WHO-fiber release propensity must be urgently improved. In the meantime, all handling and processing steps of pitch-based carbon fibers have to be accompanied by precautionary or exposure measurement-controlled safety measures to protect the employees.

Design of Automatic cutting and coating collection System Based on Optical Fiber

In order to meet the requirement of fiber splicing, the problem of low efficiency and manual operation is adopted. The device is designed and fabricated to meet the convenience and convenience of splicing and equipping in optical fber production. The simulation design and control system design of SolidEdge are discussed. At present, there isno such device in the market, and it has certain value in optical fber equipment.

28 μm all-fiber Q-switched and mode-locked lasers with black phosphorus

In past years, rare-earth-doped fluoride fiber lasers (FFLs) have developed rapidly in the mid-infrared (mid-IR) region. However, due to the lack of fiber optic devices and challenge of fluoride fiber splicing, most mid-IR FFLs have been demonstrated with free-space optic elements, limiting the advantages of all-fiber lasers for flexible delivery, stability, and compactness. Here, we report, to the best of our knowledge, the first pulsed all-fiber FFL in the mid-IR region. By taking advantage of the integration of black phosphorus flake, stable Q-switched and mode-locked pulses were obtained at 2.8 μm wavelength. We believe that this all-fiber design will promote the application of pulsed FFL in the mid-IR region.

Tapered-fiber-enabled high-power, high-spectral-purity random fiber lasing.

Random distributed feedback Raman fiber laser is a new kind of light source that can be applied to generate a high-power laser. In this Letter, we report on a high-power, high-spectral-purity random Raman fiber laser based on tapered fiber, in which the four-wave mixing (FWM) effect has been sufficiently suppressed. By choosing an appropriate tapered fiber length, we achieve a maximum random laser output of 491W, and the spectral purity can reach to as high as 94%. We carefully compare the influence of different tapered fiber lengths and splicing patterns on the FWM effect by the cutting-back method and lateral-offset splicing. The results show that the transverse modes dispersion is responsible for the appearance of FWM by compensating the phase mismatch. It is believed that a kilowatt-level random laser can be obtained by further optimizing the parameters of tapered fiber.

Yb-doped large mode area fiber for beam quality improvement using local adiabatic tapers with reduced dopant diffusion.

A newly designed all-solid step-index Yb-doped aluminosilicate large mode area fiber for achieving high peak power at near diffraction limited beam quality with local adiabatic tapering is presented. The 45µm diameter fiber core and pump cladding consist of active/passively doped aluminosilicate glass produced by powder sinter technology (REPUSIL). A deliberate combination of innovative cladding and core materials was aspired to achieve low processing temperature reducing dopant diffusion during fiber fabrication, tapering and splicing. By developing a short adiabatic taper, robust seed coupling is achieved by using this Yb-doped LMA fiber as final stage of a nanosecond fiber Master Oscillator Power Amplifier (MOPA) system while maintaining near diffraction limited beam quality by preferential excitation of the fundamental mode. After application of a fiber-based endcap, the peak power could be scaled up to 375 kW with high beam quality and a measured M2 value of 1.3~1.7.

High-spatial-resolution ultrasonic sensor using a micro suspended-core fiber.

A high-resolution fiber-optic ultrasonic sensor based on a suspended-core fiber was designed and experimentally demonstrated. The intrinsic Fabry-Perot interferometer consisting of a micro suspended-core from acid corrosion of a grapefruit fiber proved highly sensitive to a wide range of ultrasonic wave (UW) frequencies. A compact interrogation system using spectral sideband filtering was constructed for UW detection. The sensor exhibited significantly improved spatial resolution and detection sensitivity by etching the suspended-core diameter to few microns. Sensor fabrication involves only fiber splicing and corrosion, which provide a self-shielding cladding surrounding and protecting the core from collisions. This sensor is an excellent candidate for high-quality UW detection.

Magnetic field sensor based on the magnetic-fluid-clad combined with singlemode–multimode–singlemode fiber and large core-offset splicing structure

A simple, compact optical fiber magnetic field sensor is proposed and experimentally demonstrated in this paper. It is based on the magnetic-fluid-clad combined with singlemode–multimode–singlemode fiber structure and large core-offset splicing structure. It was protected by a section of capillary tube and was sealed by UV glue. A sensing property study of the combined optical fiber structure and the proposed sensor were carried out. The experimental results show that the sensitivity of the refractive index of the optical fiber sensing structure is up to 156.63 nm/RIU and the magnetic field sensitivity of the proposed sensor is up to −97.24 pm/Oe in the range from 72.4 Oe to 297.8 Oe. The proposed sensor has several other advantages, such as simple structure, small size, easy fabrication and low cost.

High sensitive temperature sensor based on a polymer waveguide integrated in an optical fibre micro-cavity

A Mach–Zehnder interferometer (MZI) based on a polymer waveguide integrated in an optical fibre micro-cavity was proposed. The micro-cavity with two symmetric openings was fabricated in single mode fibre by using femtosecond laser micromachining and fibre splicing. Then, the polymer waveguide with a length of 70 μm was integrated into the micro-cavity by using a two-photon polymerization fabrication method. The MZI exhibited a perfect interference spectrum with a fringe visibility of almost 25 dB. Owing to the high thermo-optical coefficient of the polymer material, the temperature sensitivity of the proposed MZI reached 447 pm/°C. Meanwhile, it can be used as a reliable temperature sensor as its perfect linearity (99.7%) and repeatability.

Modalmetric interferometer under Fingerprint disturbances: The effect of lateral offset between the single‐mode and multimode fiber splice

AbstractWe report on the wavelength and time‐domain responses of a lumped or distributed fiber‐optic modalmetric interferometer under a very smooth pressure (fingerprint) disturbances in the 1530–1610 nm wavelength range. A simple method to quantify such disturbances is proposed. It is shown that the lateral offset shift of 5.9 mm between the single‐mode and the multimode fiber splice makes the device even more sensitive. It was measured an electrical signal power enhancements of 3.5 and 7.5 dB for 1 m and 1.65 km multimode fiber link, respectively.

CO2 Laser‐Based Fiber Splicing System

AbstractThe outstanding spatial and temporal flexibility and precise control of a laser beam enable automated, reliable and individualized production of single‐ and multi‐mode fiber components. These components can be used for fiber lasers and amplifiers, fiber‐coupled diode lasers and fiber‐based beam delivery systems. The cost‐efficient customization of fiber components is important for the support of the wide range of laser wavelengths and fiber types used for different applications in the laser market. In the following sections, this will be representatively described for our CO2 laser‐based fiber splicing system, which is made for individual fiber splicing tasks using large optical elements such as fiber end caps.

Sensitivity improvement by fusion splicing of single mode fibers with core offset

We demonstrate a Fabry-Perot fiber cavity for strain measurement with highly improved sensitivity. The cavity is fabricated by the fusion splicing of two etched single-mode fibers with a core offset in the X axis or both X and Y axes. It is found that the strain sensitivity can be increased from 2.39 to 7.75pm/μe by adopting offset splicing. Such a Fabry-Perot cavity device is compact in size, simple in structure, easy in fabrication and of low cost, and has high potential in strain sensing.

A micro S-shaped optical fiber temperature sensor based on dislocation fiber splice

We fabricated a simple, compact, and stable temperature sensor based on an S-shaped dislocated optical fiber. The dislocation optical fiber has two splice points, and we obtained the optimal parameters based on the theory and our experiment, such as the dislocation amount and length of the dislocation optical fiber. According to the relationship between the temperature and the peak wavelength shift, the temperature of the environment can be obtained. Then, we made this fiber a micro bending as S-shape between the two dislocation points, and the S-shaped micro bending part could release stress with the change in temperature and reduce the effect of stress on the temperature measurement. This structure could solve the problem of sensor distortion caused by the cross response of temperature and stress. We measured the S-shaped dislocation fiber sensor and the dislocation fiber without S-shape under the same environment and conditions, and the S-shaped dislocation fiber had the advantages of the stable reliability and good linearity.