Low-loss Splicing Research Articles

The Adoption of Chalcogenide Glass Fiber as Pulse Stretcher in an All-Fiber Structured 2 μm Chirped Pulse Amplification System

We present the development of an As <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> fiber-based reusable inline optical connector; and, for the first time to the best of our knowledge, integrated it into a 2 μm chirped pulse amplification system as the pulse stretcher. By this mechanism, a near 20 times pulse stretching ratio was achieved in 0.5 m-long this As <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> fiber and the introduction of insertion loss as low as 2.84 dB while it was connected with silica fiber. After the follow-up fiber amplification and self-compression mechanism, the laser average output power was boosted to 1.97 W and pulse duration was optimized to 2.53 ps. Moreover, to further inspect the laser pulse property, the pulses were then delivered into a 5.3 m-long ZrF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> -BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -LaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -AlF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -NaF (ZBLAN) fiber which was fusion spliced to SM1950 fiber. Thanks to the 0.4-dB low fusion splice loss between these fibers, a 1.56-W supercontinuum source with bandwidth of 1.93-3.50 μm is obtained. The measured two hours of root-mean-square value of power fluctuation of this laser source is 0.13%, indicating an ultra-high long-term power stability. This work will lay a solid foundation in the realization of the all-fiber structured high-power thulium-doped fiber amplifier with high compactness.

Diode-pumped triple-clad fiber MOPA with an output power scaling up to 4.67 kW.

In this Letter, we have demonstrated a triple-cladded fiber (TCF)-based master oscillator power amplifier (MOPA), with an output power scaling up to 4.67 kW, an optical-to-optical efficiency of 78%, and a beam quality factor ${{\rm M}^2}$M2 of 1.57. The MOPA output power was limited by stimulated Raman scattering (SRS) of which our design yielded a 31.2 dB suppression ratio at the 4.67 kW output power. Such a unique design of a TCF-based structure allows a wide range of flexibility over fiber parameters, mitigation of nonlinear effects, low-loss splice integration, reliable high-power pump guiding in turn, and an ease in overall thermal management at multi-kW output power levels. Together with direct diode-pumping configuration, TCF-based designs promise thermally and mechanically robust, compact, and highly efficient MOPA systems of a superior beam quality.

Furtherance in Splicing Technique of Optical Fiber Communication

The improvement in technology over long distance communication using optical fiber has been regulated over past few decades, and it took drastic enhancement in one of the major parameter for joining two OFC cable (splicing). The different experiments performed in order to bring about the result that can give nearly 0dB splice loss when there is shifting of entire set up of Optical Fiber Communication. The splicing loss is created by the joining of two SMF using fiber optic fusion splicing. The objective of this paper is to determine the low splice loss in joining two single mode or multimode optical fiber, such that long distance communication that required multiple infrastructure assembly for its operational unit can be made relocatable as there is large investment and material and electronic circuitry is associated to it. Therefore to reduce that cost we have sets of analysis that splicing loss can be reduced to 0dB for SMFSMF end face connection or at least no improvement in splice losses while relocation of OFC infrastructure from one place to other place as the result of the tested experiment. Based on experiment conducted we came to conclusion that with essential requirements for establishing a low-loss and high-speed communication line using optical fibers, the need for quality of splicing technology along with perfect core alignment angle is required to reduce splice loss, such that the infrastructure can be shifted to many different location without any additional cost of new material and new resources. The exact measurement of splice loss can be insured by another set of formula which we came across during the experimental performance.

Splicing of silica-based MOF and standard SMF: Loss evaluation using an enhanced field model

Abstract Splice losses between the transmission optical fibers and the fiber-based devices have been considered as one of the bottlenecks in accomplishing the optical networks. Consequently, the practical utilization of specialty optical fibers such as triangular solid-core microstructured optical fibers (T-MOFs) in conjunction with splicing to dissimilar standard single-mode fiber (SMF) prerequisite a trustworthy, repeatable and robust low-loss splicing. Utilizing an enhanced field model, we appraised the splice losses between two similar T-MOFs without considering collapsing of air-holes at the joint interface with azimuthal and transverse offsets, and the splice loses between T-MOF and classical SMF are also explored. Collapsing of air-holes can facilitate to minimize the mode-profile inconsistency at splicing interface and hence, lowering the losses; therefore, we evaluated the mode-field diameter (MFD) as a function of collapse ratio. We reported splice losses of ~0.378 dB and ~5.032 dB at 1.55 µm between two identical T-MOFs with Λ = 4.0 µm, for the case of azimuthal and transverse offset, respectively. Also, we examined the consistency of our results by evaluating the relative errors, and the comparisons have been incorporated with those as reported in the literature.

Ultra-efficient, 10-watt-level mid-infrared supercontinuum generation in fluoroindate fiber.

A 10-watt-level mid-infrared supercontinuum (SC) spanning 0.8-4.7μm with ultra-high-power conversion efficiency is generated in a piece of fluoroindate (InF3) fiber. The pump laser is a master oscillator power amplifier system seeded by a mode-locked fiber laser operating at 1956nm with pulse repetition rate and pulse duration of 33MHz and 60ps, respectively. A piece of InF3 fiber is fusion spliced to the output end of the pump light source with a low fusion splicing loss of 0.12dB. An endcap made of multimode aluminum fluoride fiber is used to protect the fiber tip from possible optical or thermal damage. Benefiting from the fiber endcap as well as the low-loss splicing joint between silica and InF3 fiber, high-power SC generation is achieved with maximal output power of 11.3W. Furthermore, the long wavelength edge of the obtained SC spectrum is extended to 4.7μm. This Letter, to the best of our knowledge, not only demonstrates the first 10-watt-level SC generation in InF3 fibers, but also achieves record power conversion efficiency of 66.5% among reported 10-watt-level fluoride-fiber-based SC laser sources.

Filament fusion of hollow-core photonic crystal fiber and single mode fiber: numerical simulation and experimental analysis

This paper proposes a high strength and low loss splicing method suitable for coupling between hollow-core photonic crystal fiber and single mode fiber, based on filament fusion technology. The essence of this method is keeping the temperature of the single mode fiber above the melting temperature, and that of the hollow-core photonic crystal fiber at around the softening point temperature by modifying several splice parameters, which can be pre-evaluated by numerical simulation. Experimental results have verified the accuracy of the numerical model, and ideal splicing results can be made under proper splice parameters. In this paper, repeatable splicing between hollow-core photonic crystal fiber and single mode fiber with a loss of less than 2.3 dB, and a strength higher than 38 Kpsi is demonstrated.

Optimum splicing of high-index core microstructured optical fibers and traditional single-mode fibers using improved field model

Traditional fusion splicing technologies are not usable for the high-index core triangular lattice microstructured optical fibres (MOFs), as the characteristic air-holes pattern often collapse during splicing, significantly increasing splice losses due to distortion of the waveguiding structure. The low-loss splicing of MOF and the traditional single-mode fibre (SMF) can be achieved by enlarging the mode-field diameter (MFD) of MOF, facilitating to an optimum mode-field match at the splicing interface. Using our recently developed improved field model Sharma and Sharma (2016), we aim to investigate the modal characteristics of high-index core MOF as a mode-field expander, and low-loss splicing between an MOF and the standard step-index single-mode fiber by using controlled all air-hole collapse method. For comparison, experimental and the numerical simulation results have been included, as available in the literature. Relative errors are also given.

空芯反谐振光纤与单模光纤的低损耗熔接研究

空芯反谐振光纤与单模光纤的低损耗熔接研究

Extremely High-Efficiency Coupling Method for Hollow-Core Photonic Crystal Fiber

We report a novel low-loss splicing approach for hollow-core photonic crystal fiber (HC-PCF) and conventional single mode fiber (SMF) by inserting an etched SMF tip into the hollow core. If the divergence solid angle (DSA) of the inserted fiber tip is smaller than the guiding solid angle (GSA) of HC-PCF, all the radiated optical power from the tip will be collected by PCF with an extremely high coupling efficiency and guided by the PCF based on photonic bandgap effect. A DSA-GSA matching model is proposed to calculate the efficiency for different splicing situations. In the optimal condition of GSA > DSA, the transmission loss could approach zero, only including the scattering loss of etched fiber. Then, we experimentally demonstrate the splicing between NKT HC19-1550-01 and SMF-28 with coupling efficiency of 84.5%, agreeing well with the theoretical result of 85%. In addition, our proposed method is coaxiality error free, angle deviation free, and insertion length insensitive. This new technique is expected to provide new possibilities in some special system designs for HC-PCF-based applications.

Supercontinuum Generation in an Ytterbium-Doped Fiber Amplifier With Cascaded Double-Clad Passive Fiber Tapers

Supercontinuum (SC) generation directly from an Ytterbium-doped fiber amplifier (YDFA) has many advantages such as high output power, low splicing loss, and high optical to optical conversion efficiency. However, the output spectrum can only extend to longer wavelength. We report a method to further extend the spectral range of SC generated in an YDFA at short wavelength direction by using cascaded double-clad passive fiber tapers. A 750 ps seed pulse at 1060 nm is amplified to 15.9 W and spectrally broadened from 1000 to 1600 nm in an YDFA system. Using this broadband source to pump cascaded double-clad passive fiber tapers, a 14.1 W SC source is obtained, covering 630 to 2000 nm, which is in an all-fiber and low-cost structure. It is found that, in fiber tapers, especially at the taper waist, the frequency shift rate of solitons increases significantly, and those red-shifted solitons are group-velocity matched to dispersive waves even in the red wavelength region. To our best knowledge, this is the first time there has been generation in tapered double-clad passive fiber.

End-View Image Processing Based Angle Alignment Techniques for Specialty Optical Fibers

We propose two end-view-based digital image processing algorithms for high-precision rotational angle alignment of specialty optical fibers. The first technique is based on the cross-correlation calculation between images of two fiber ends. Accurate alignment can be achieved between identical specialty optical fibers with arbitrary end face structures. The other one is based on the self-correlation method. Two fibers with different refractive index profiles in the fusion splicer can be rotated to preset angles independently with high precision. Accurate angle alignment of less than 0.5° uncertainty and low average splicing loss for seven-core multicore fibers have been achieved in experiment. To speed up the alignment process, we further proposed two simplified algorithms for the above-mentioned techniques. Time consumption can be reduced by about 50% with acceptable alignment accuracy. We confirmed that all the methods are suitable for other kinds of specialty optical fibers, such as polarization maintaining fibers and photonic crystal fibers.

Design and demonstration of single-mode operation in few-mode optical fiber with low-bending loss

Single-mode operation with low-bending loss based on few-mode optical fiber is investigated. The fiber is designed with a group of ring modes in the cladding. The higher-order modes in the fiber can be eliminated by splicing with the single-mode optical fiber and bending the fiber to induce a strong coupling between the ring modes and the higher-order modes. Experimental results show that the bending losses of the LP01 mode can be lower than 0.001 dB/turn for a low-bending radius of 7.5 mm. The low-bending loss and the low splicing loss characteristics are also demonstrated. The proposed fiber can be bent multiple turns with a small bending radius which is preferable for fiber-to-the-home-related applications.

High strength fusion splicing of hollow core photonic crystal fiber and single-mode fiber by large offset reheating

Abstract High strength fusion splicing hollow core photonic crystal fiber (HC-PCF) and single-mode fiber (SMF) requires sufficient energy, which results in collapse of the air holes inside HC-PCF. Usually the additional splice loss induced by the collapse of air holes is too large. By large offset reheating, the collapse length of HC-PCF is reduced, thus the additional splice loss induced by collapse is effectively suppressed. This method guarantees high-strength fusion splicing between the two types of fiber with a low splice loss. The strength of the splice compares favorably with the strength of HC-PCF itself. This method greatly improves the reliability of splices between HC-PCFs and SMFs.

Differential Modal Gain Reduction of L-band 5-Mode EDFA Using EDF With Center Depressed Core Index

We report a 5-mode erbium-doped fiber (EDF) amplifier operating in the L -band (1570–1605 nm) designed to extend the bandwidth of mode division multiplexed transmission. We design an EDF with a center depressed core index and a ring-doped erbium concentration profile to obtain a low differential modal gain (DMG) and a low splice loss with a graded-index fiber as a transmission line. Then, we fabricate a center depressed core EDF and realize a gain of 20 dB for all the modes and a low DMG with a deviation of less than 3 dB in the 1570–1605 nm range with a 48-m-long erbium-doped fiber when the pump mode is ${\rm{LP}}_{{01}}$ mode.

Comparative theoretical study of polarising Panda-type and microstructured fibres for fibre-optic gyroscope

Comparative study is fulfilled for different polarising fibres: Panda fibres with match-clad and depressed-clad W-profiles, along with microstructured fibres. Comparison is made for their spectral width of single-polarisation windows taking into account bending, and for their splice losses with conventional fibres. A new type of match clad fibre is also proposed polarising even without bending. It is shown that the optimal is W-fibre Panda. At the same time, truly broadband polarising microstructured fibres demonstrate enormously large splice losses, whereas those of them with relatively low splice losses could not be wound into the coil of reasonable size due to large bend losses.

Fusion splice techniques for multicore fibers

Fusion splice techniques for multicore fibers (MCFs) are discussed here. We demonstrate a swing electrode system for uniform discharge and an end-view function for automatic and precise core alignment. The influence of the cleaved angle was investigated for stable and low-loss fusion splicing. Using these techniques, we achieved a low-loss splicing of not greater than 0.3 dB at all cores for a 32-core fiber and for all modes for a 2-LP-mode 12-core fiber, in which a precise core alignment and a uniform discharge of wide range were required. These results indicate that the techniques we proposed are promising for fusion splicing of MCFs.

Ultrabroadband polarization splitter based on three-core photonic crystal fiber with a modulation core.

We design an ultrabroadband polarization splitter based on three-core photonic crystal fiber (PCF). A modulation core and two fluorine-doped cores are introduced to achieve an ultrawide bandwidth. The properties of three-core PCF are modeled by using the full-vector finite element method along with the full-vector beam propagation method. Numerical results demonstrate that an ultrabroadband splitter with 320 nm bandwidth with an extinction ratio as low as -20 dB can be achieved by using 52.8 mm long three-core PCF. This splitter also has high compatibility with standard single-mode fibers as the input and output ports due to low splicing loss of 0.02 dB. All the air holes in the proposed structure are circular holes and arranged in a triangular lattice that makes it easy to fabricate.

Low-Loss Microfiber Splicing Based on Low-Index Polymer Coating

Splicing is an essential technique for optical microfibers. In this letter, we report on low-loss splicing of evanescent-wave-coupled microfibers by coating them with a low-index polymer named high-substituted hydroxypropyl cellulose (H-HPC). The polymer coating can significantly increase the overlap of mode fields and effectively enhance the coupling strength. As a result, the transmission ratio can reach 94% over a wavelength range of 100 nm by controlling the coating thickness and length. H-HPC coating also enables a high mechanical strength at the joint segment. The coated microfibers can stand a pulling force up to 1 N. Compared with existing techniques, the present splicing method offers a great operation convenience and easiness.

Highly stable, monolithic, single-mode mid-infrared supercontinuum source based on low-loss fusion spliced silica and fluoride fibers.

A 0.8 to 4.5 μm highly stable all-fiber spliced mid-infrared supercontinuum (SC) source was presented. The joint between the single-mode (SM) pump silica fiber and the ZBLAN fiber (ZrF4 - BaF2 - LaF3 - AlF3 - NaF, a type of fluoride fiber) was fusion spliced, which greatly improved the SC's stability. The low-loss splicing was guaranteed by the similar mode field areas of the fundamental mode LP(01) of the silica and ZBLAN fibers. At the splicing joint the ZBLAN fiber enveloped the silica fiber, thus increasing the robustness of the splice. A low splicing loss of less than 0.1 dB was calculated, which ensured that the whole SC source was very reliable. The SC had a maximal average power of 550.8 mW with a 1.5 dB spectral bandwidth ranging from 2642 to 4065 nm. In particular, the SC power for λ>3.8 μm was measured to be 116.1 mW with a power ratio of ∼21.1% of the total SC power. Perfect Gaussian beam profiles of the SC source demonstrated its SM operation. Over 12 h of continuous operation of this SC source showed its outstanding power stability with a root mean square variation of 0.59%, which also demonstrated the high quality of the fusion spliced joint.

Low-Splice Loss Design of DS and DF Single-Mode Fibers

Low-Splice Loss Design of DS and DF Single-Mode Fibers