Fusion Splicing Process Research Articles

High-coupling efficiency and robust fusion splicing between fluorotellurite and chalcogenide fibers

We demonstrate a low-loss and high-robustness fusion splicing point between fluorotellurite fiber and arsenic sulfide-based chalcogenide fiber (As2S3) by using an asymmetric fiber splicing technology. The splicing loss of point is less than 0.55 dB at the wavelength of 1.55 μm, and the monitored tension is 129 g by tuning the distance of the fusion splicing head offset in the fusion splicing process. Using an all-fiber testing system, the fusion splicing point loss between the 1.55 μm testing light source tail fiber (silica fiber) and the fluorotellurite fiber is 0.503 dB. The output power from the As2S3 fiber is 0.91 W with a testing light source of 2 W, and the temperature of the splicing joint shows no evident increase. This finding indicates that the fusion splicing point offers excellent beam quality. This work lays a solid foundation for building an all-fiber cascaded system generating mid-infrared supercontinuum with high-coupling efficiency between mid-infrared soft-glass fibers.

Fiber in-line interferometer based on air-cavity with suspended fiber-core for sensing

We demonstrate a new type of fiber in-line Mach–Zehnder interferometer (MZI). The device is fabricated by firstly inscribing a ring structure surrounding the fiber core at the ends of two single-mode fibers using a femtosecond laser micromachining technique and then fusion-splicing the two fibers with end structures. Due to the high temperature produced in the fusion splicing process, the ring structure expands rapidly and results in an inner air-cavity with a suspended fiber-core. The incident light traveling in the fiber core is split into two parts at the edge of the inner air-cavity, one propagating through the air cavity while the other remains traveling along the suspended fiber core; both are collected by the fiber core at the air-cavity end, thus forming an in-line MZI. The device has good high-temperature sustainability up to 900 °C. Moreover, by drilling a hole on top of the air-cavity, an open micro-channel can be created for air pressure measurement with a pressure sensitivity of ~−8214.68 pm MPa−1.

Parallel Fabry-Perot interferometers fabricated on multicore-fiber for temperature and strain discriminative sensing.

We experimentally demonstrate parallel Fabry-Perot interferometers (FPIs) fabrication in multicore-fiber with individually variable cavity length, for the purpose of discriminative sensing of temperature and strain. First, we theoretically find that, in order to obtain a small condition number of sensitivity matrix, it is necessary to fabricate parallel FPIs with large cavity difference in single multicore fiber. Then, parallel FPIs are inscribed by femtosecond laser selective micro-holes drilling on the seven-core fiber facet, together with fiber fusion splicing process. By the use of image processing algorithm, individual core position is precisely locked, and then parallel FPIs can be obtained on arbitrary two cores of seven-core fiber. With the location of parallel micro-holes and duration time of fiber fusion splicing adjusted, parallel FPIs with different cavity length of 26µm and 61µm can be simultaneously obtained at the central core and surrounding core, respectively. Consequently, each FPI possesses different sensitivity towards environmental temperature and strain. Finally, a proof-of-concept experiment verifies that relative measurement errors of both temperature and strain discriminative sensing are less than 0.5% and 2.5%, respectively.

Intensity-modulated temperature sensor based on fiber interferometer with optical bandpass filtering

An intensity-modulated temperature sensor based on fiber Mach-Zehnder interferometer (MZI) is proposed and demonstrated. The sensor is constructed using single mode fiber (SMF) and multimode fiber (MMF) in SMF-MMF-SMF-MMF-SMF sequence. The sensing system is power-interrogated, relies on an optical bandpass filtering of the sensor output at a predetermined wavelength which converts any change in sensor spectra into power change. This sensing scheme is very cost effective, as the temperature can be directly quantified from photodetector voltage measured at the filter output. Furthermore, sensor fabrication only involves conventional fusion splicing process between standard SMF and MMF. Experimental result shows that a sensor with length 20 mm produces linear response of -0.48 mV/°C at 1532 nm passband wavelength, good long-term stability with negligible voltage drift and fluctuation, and wide measurement range within 30-180°C. The proposed scheme potentially can be applied in fiber interferometer sensors for measurement of other physical parameters such as strain, refractive index and vibration.

Low-loss semi-reflective in-fiber mirrors

This paper presents a method for the efficient production of all-fiber semi reflective mirrors suitable for fiber sensors and other all-fiber device applications. The mirrors are obtained by the short duration etching of a standard single mode fiber in hydrofluoric acid, followed by an on-line feedback-assisted fusion splicing process. Fiber mirror reflectance up to 9.5% with excess losses below 0.25 dB were produced in practice, which is in good agreement with provided theoretical and modeling analyses. Control over the etching time and fusion splicing process allows for balancing between reflectance and transmittance, while maintaining low excess loss of experimentally produced mirrors.

光子晶体光纤熔接过程中的空气孔力学特性

光子晶体光纤熔接过程中的空气孔力学特性

Internal mirror optical fiber couplers

A description is given of a way of making mirrored fiber couplers, and test results on both multimode and single-mode taps are reported. The couplers were produced by a fusion splicing process similar to that used for making mirrors oriented normal to the axis in multimode and single-mode fibers. These mirrored fibers serve as compact directional couplers with low excess optical loss ( approximately=0.2 dB for multimode and 0.5 dB for single mode at 1.3 mu m) and excellent mechanical properties. The reflectance is found to be wavelength dependent and strongly polarization dependent, as expected. >

Interferometric examination of spliced optical fibers

We used a Zeiss-Linnik interferometer to obtain interferograms of fusion-spliced optical fibers. A common feature is the presence of buckling of the fiber material on both sides of the splicing point. This resulted from the fusion splicing process. Their heights ranged from 1 to 10 μm, some 300 μm apart for graded-index optical waveguides of 50-μm core and 125-μm clad diameters. Few cases showed the presence of buckling 140 μm from the point of fusion splicing. The power loss resulting from fusion splicing for the specimens examined interferometrically was measured. It is found that the greater the buckling, the greater the power loss. A height of 2λ or less (λ = 535 nm) gave no detectable loss.