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.
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 report research results with regard to AlGaAs/GaAs structure processing for THz quantum-cascade lasers (QCLs). We focus on the processes of Ti/Au cladding fabrication for metal–metal waveguides and wafer bonding with indium solder. Particular emphasis is placed on optimization of technological parameters for the said processes that result in working devices. A wide range of technological parameters was studied using test structures and the analysis of their electrical, optical, chemical, and mechanical properties performed by electron microscopic techniques, energy dispersive x-ray spectrometry, secondary ion mass spectroscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, and circular transmission line method. On that basis, a set of technological parameters was selected for the fabrication of devices lasing at a maximum temperature of 130 K from AlGaAs/GaAs structures grown by means of molecular beam epitaxy. Their resulting threshold-current densities were on a level of 1.5 kA/cm2. Furthermore, initial stage research regarding fabrication of Cu-based claddings is reported as these are theoretically more promising than the Au-based ones with regard to low-loss waveguide fabrication for THz QCLs.
We report our research on processing of AlGaAs/GaAs structures for THz quantum-cascade lasers (QCLs). We focus on
the processes of fabrication of Ti/Au claddings for metal-metal waveguides and the wafer bonding with indium solder.
We place special emphasis on the optimum technological conditions of these processes, leading to working devices. The
wide range of technological conditions was studied, by use of test structures and analyses of their electrical, optical,
chemical and mechanical properties, performed by electron microscopic techniques, energy dispersive X-ray
spectrometry, secondary ion mass spectroscopy, atomic force microscopy, fourier-transform infra-red spectroscopy and
circular transmission line method. On the basis of research a set of technological conditions was selected, and devices
lasing at the maximum temperature 130K were fabricated from AlGaAs/GaAs structures grown by molecular beam
epitaxy (MBE) technique. Their threshold-current densities were about 1.5kA/cm<sup>2</sup>. Additionally we report our initial
stage research on fabrication of Cu-based claddings, that theoretically are more promising than the Au-based ones for
fabrication of low-lossy waveguides for THz QCLs.
Quantum cascade lasers (QCL’s) have proven their usefulness as light sources in many applications, like remote gas
sensing, molecular spectroscopy or free-space communication. In most cases the high-quality low-divergence beam is
desired. This work presents the theoretical analysis of QCL’s beam divergence. The electromagnetic field in the
resonator is calculated according to effective index method. Theoretical results are compared with measurements.
The paper presents results of experimental investigations of spatial distribution of radiation emitted by quantum
cascade lasers. Measurements have been performed by means of a unique goniometric profilometer specially de-
signed for the large angle laser beams. The advantages and limitations of the set-up and the applied experimental
method are discussed. The obtained results have enabled the analysis of dependence of geometry of the beam
on the geometry of the laser structure and on the mount method of the laser chips. The angular divergence of
the beams has also been tested as a function of laser power supply.