We present and discuss an experimental fiber-optic sensing system developed for application in a coal mine. One of the major issues of coal mine engineering is the condition of the rock mass above the roadways in which miners extract coal. The condition is typically monitored using measurement anchors with electronic strain gauges. In the demonstrated system, the electronic sensors are replaced with FBGs. A fundamental cell of the network consists of gratings that are glued to a special groove on the anchor, while the output signal is read out with an interrogation system. The interrogator is realized either using a commercially available device or with a photonic integrated circuit. The system has been assembled and tested both in the anchor laboratory and in a test site in a roadway of a mine. The first characterization results are promising and prove the feasibility of fiber-optic sensors for rock mass monitoring.
The first ruby laser, developed by Theodore Maiman in 1960 initiated the era of laser technology, characterized by rapid progress in all fields benefiting from unique features of coherent radiation sources. Among various types of lasers developed so far, fiber lasers plays continuously increasing role in those areas where high output powers and high efficiency combined with single mode operation and excellent heat dissipation are of concern. In the recent years, fiber laser-based systems dominated the market of material processing (cutting, welding, hardening, etc.) and military systems, while rare-earth doped fiber amplifiers became a key element of modern telecommunication systems.
It should be noted, however, that despite a large number of fiber lasers manufacturers around the world, there are only a few companies with technological skills enabling manufacturing the active fibers of sufficient quality. In this work we would like to show the progress of Polish research teams in this field. The R&D works, conducted for the last few years in cooperation with Laboratory of Fiber Optic Technology at the Faculty of Chemistry of Maria Curie-Skłodowska University, Lublin, Poland, enabled mastering the technology of manufacturing the first active optical fibers applicable to laser systems.
In this work the overview of the technology will be presented together with the results of characterization of ytterbium, erbium, thulium and dysprosium doped optical fibers, dedicated to laser applications. The absorption/emission spectra and luminescence kinetics profiles of active preforms and optical fibers will be discussed and compared to the results obtained for commercially available samples. Also the results of amplification and laser experiments will be presented and perspectives of the active fiber technology in Poland will be discussed.
This work has received partial support from the National Centre for Research and Development through project NMKM+ (TECHMATSTRATEG1/348438/16/NCBR/2018).
Increasing demand for high data transmission rates and bandwidth availability driven by the rapid development of the broadband services becomes challenging in the context of constraints imposed by nowadays exploited telecommunication optical fibers. Based on single-mode fibers and multiplexing in the wavelength domain (wavelength division multiplexing, WDM), the current technology seems to have reached its fundamental limits. At present, two promising technologies are a subject of intensive research. One of them is the increase of the data transmission through multiplying the number of fiber cores, thus implementing the concept of Multi-Core Fibers (MCF), where each core is used as a separate data transmission channel. The second widely investigated technique is based on the idea of mode division multiplexing (MDM), where different transverse modes of a Few-Mode Fiber (FMF) can be used as different carriers for data channels.
In this work, we demonstrate the results of R&D works and the comprehensive tests of the few-mode fibers developed within the project NMKM+. Developed few-mode fibers (both passive and active) and their commercially available counterparts have been tested with respect of transmission parameters and applicability to the real telecom systems. In particular, guided mode profiles, numerical apertures, OTDR, and dispersion characteristics for the passive fibers have been recorded and compared. Also, methods of selective excitation and detection of singular modes have been discussed and partially verified. The results of data transmission experiments have been performed and discussed with respect to the quality of transmitted signals. These have been complemented by the amplification experiments with the use of erbium-doped few-mode fibers in “classical” and microstructural geometry. The results were studied and analyzed, showing the potential for future optimization.
Acknowledgement: This work has received support from the National Centre for Research and Development through project NMKM+ (TECHMATSTRATEG1/348438/16/NCBR/2018).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.