We fabricated three silica glass preforms with different cross-sections, which were used to draw optical fibers. A classic preform had a circular shape and was prepared on the MCVD machine, second preform with a circular outer shape and hexagonal core was fabricated by the hybrid method, last preform with hexagonal core and outer shape and was fabricated by stacking method. Each preform were used to draw series of fibers with parameters corresponding to the geometry of typical telecommunication fibers. In following part of our experiment all fibers were used in microbending tests.
We present an alignment procedure which allows for precise gluing of a structure with an optically pumped quantum emitter to the end face of zirconia ferrule with a specially fabricated high numerical aperture single-mode fiber. The proposed method is an important step towards building a single-photon source based on an InGaAs quantum dot emitting in 1.3 μm range and located deterministically in a microlens fabricated by in-situ electron beam lithography and plasma etching to improve the photon extraction efficiency. Since single QDs are very dim at room temperature which hinders QD-fiber adjustment by maximizing the collected photoluminescence signal, the developed method uses light back-reflected from the top surface of the sample with microlens as a feedback signal. Using this approach, we were able to position the high-NA fiber over the center of the microlens with an accuracy of about 150 nm in a lateral direction and 50 nm in a vertical direction. The alignment accuracy was confirmed by following the room temperature emission from quantum wells embedded in a reference microlens. We also present initial low temperature tests of the coupling system mounted in a compact and portable Stirling cryocooler.
Monitoring the geometry of an moving element is a crucial task for example in robotics. The robots equipped with fiber bend sensor integrated in their arms can be a promising solution for medicine, physiotherapy and also for application in computer games. We report an all-fiber intensity bend sensor, which is based on microstructured multicore optical fiber. It allows to perform a measurement of the bending radius as well as the bending orientation. The reported solution has a special airhole structure which makes the sensor only bend-sensitive. Our solution is an intensity based sensor, which measures power transmitted along the fiber, influenced by bend. The sensor is based on a multicore fiber with the special air-hole structure that allows detection of bending orientation in range of 360°. Each core in the multicore fiber is sensitive to bend in specified direction. The principle behind sensor operation is to differentiate the confinement loss of fundamental mode propagating in each core. Thanks to received power differences one can distinguish not only bend direction but also its amplitude. Multicore fiber is designed to utilize most common light sources that operate at 1.55 μm thus ensuring high stability of operation. The sensitivity of the proposed solution is equal 29,4 dB/cm and the accuracy of bend direction for the fiber end point is up to 5 degrees for 15 cm fiber length. Such sensitivity allows to perform end point detection with millimeter precision.
We report on fabrication of a new type high birefringent microstructured polymer fiber with a PMMA stress applied element in the core. An inner part of preform consists regular three rings of holes, made by drilling method. Inside the microstructure we drilled an additional hole, where a special type – strongly stressed PMMA rod was placed. The manufactured preform was measured in an polarimetric microscope configuration where we observed very large internal stresses - especially seen in a core area.
We present the novel 7-core and 19-core hole-assisted fibers designed to satisfy the most demanding requirements of the ITU-T G.657.B3 recommendation for bend-insensitive fibers. The fibers are compatible with standard single-mode fibers with regard to modal properties, dispersion characteristics, and transmission loss. The fibers presented exhibit no crosstalk and it is possible to use them together with other multiplexing methods like CWDM or DWDM. Dedicated fanin/ fan-outs have been created in order to make immediate use in industry possible. The hole-assisted 19-core fiber with single-mode cores is being presented for the very first time.
The authors designed and fabricated optical power splitters, which make an alternative solution to existing commercial products. The proposed solutions use multicore microstructured optical fiber designed for new generation telecommunication networks made in Spatial Division Multiplexing (SDM) system. The splitters presented in this paper aim to have low loss and to be compatible with existing elements of optical networks, and in the same time to eliminate disadvantages of existing splitters. Two designs presented in this paper are made in all-fiber technology in order to ensure high environmental stability. The authors present detailed description and experimental results for both optical power splitters’ designs.
In presented work, we examined the structures of dual-core fibers paying special attention to the possibility of using them for sensing. In the hole-assisted fiber structure, the character of propagation in the cores was changed fluently, by post-processing the fiber, i.e. tapering with collapsing the holes. Fiber post-processing changed the conditions for supermodes interference and thus the different scale of power transfer between cores was observed. In the paper we investigated the influence of the taper parameters (taper waist, length and ratio) on the properties of the fiber. We have also studied the behaviour of the transmitted signal, while putting post-processed segment of fiber into different external conditions. Presented research shows a great potential of using modified hole-assisted fibers as sensing elements.
The use of optical elements and other photonic components makes it possible to overcome telecommunication satellite’s bottleneck problems such as size and weight reduction. Despite the unquestionable potential of such elements, nowadays they are not widely used in systems operating in space. This is due to many factors, including the fact that space radiation has disruptive influence on optical fibre. Namely it introduces additional radiation induced attenuation (RIA) that significantly lowers efficiency of optical fibre based systems. However, there is a possibility to produce radiation-hardened (rad-hard) components. One of them is seven core erbium-doped active fibre (MC-EDF) for fibre amplifiers in satellites that we have been developing. In this paper we present a detailed description of seven core structure design as well as experimental results. We report that average gain of 20 dB in C-band with noise figure of 5.8 dB was obtained. We also confirmed that low crosstalk value for a multicore fibre amplifier based on our fibre can be achieved.
We present two polymer birefringent fibers with enhanced polarimetric sensitivity to hydrostatic pressure. In the first fiber, with birefringence induced by the arrangement of holes in the microstructured cladding, an increased sensitivity to pressure was obtained by enlarging selected holes in the cladding. The second is a side-hole fiber with an elliptical core made of polymethyl metacrylate–polystyrene (PMMA/PS) copolymer and pure PMMA cladding. The fiber core is located in a narrow PMMA bridge separating the holes. The transmission and sensing characteristics of both fibers are compared, including spectral losses, birefringence, polarization cross-talk and polarimetric sensitivity to hydrostatic pressure.