Integrating Radio-Over-Fiber Communication System and BOTDR Sensor System

Abstract

In this paper, we propose and experimentally demonstrate for the first time, the integration of a radio-over-fiber (RoF) communication system and a Brillouin optical time-domain reflectometry (BOTDR) distributed sensor system using a single optical fiber link. In this proof-of-concept integrated system, the communication system is composed of three modulation formats of quadrature phase-shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM) and 64-QAM, which are modulated onto an orthogonal frequency division multiplexing (OFDM) signal. Whereas, the BOTDR sensor system is used for strain and/or temperature monitoring over the fiber distance with a spatial resolution of 5 m using a 25 km single-mode silica fiber. The error vector magnitude (EVM) is analyzed in three modulation formats in the presence of various BOTDR input pump powers. Using QPSK modulation, optimized 18 dBm sensing and 10 dBm data power, the measured EVM values with and without bandpass filter are 3.5% and 14.5%, respectively. The proposed system demonstrates a low temperature measurement error (±0.49 • C at the end of 25 km) and acceptable EVM values, which were within the 3GPP requirements. The proposed integrated system can be effectively applied for practical applications, which significantly reduces the fiber infrastructure cost by effective usage of a single optical fiber link.Sensors 2020, 20, 2232 2 of 8 ago, the use of Brillouin based distributed fiber sensor systems for structural health monitoring applications has increased rapidly [5,6], due to their high measurement range up to tens of kilometers. The familiar techniques in time-domain based Brillouin fiber sensors are; Brillouin optical time-domain reflectometry (BOTDR) [7] and Brillouin optical time-domain analysis (BOTDA) [8]. The BOTDR system is implemented using spontaneous Brillouin scattering (SpBS) which requires access to one end of the fiber. The BOTDA system uses stimulated Brillouin scattering (SBS) with counter-propagating continuous probe wave and access to both ends of the fiber is essential. Providing a new fiber infrastructure for a distributed sensing system comes at a huge cost with much complexity, which discourages their widespread use. Therefore, sharing an existing data transmission fiber infrastructure for distributed sensing offers cost-effectiveness and efficiency savings. For example, the railway industry uses a fiber infrastructure installed along the track-side for data transmission. The integration of distributed sensing system with the existing optical cable can be used for real-time condition monitoring of land-slides, track ballast, snowdrifts, flooding and line-side fire detection [9]. The integration of distributed sensing and active data transmission using a single optical fiber is an unexplored area of research.In this paper, we demonstrate a proof-of-concept of simultaneous integration of fiber communication system and the BOTDR sensor system using a single optical fiber, demonstrating the performance of both systems experimentally. For...

Phase-Sensitive Optical Time Domain Reflectometry With Rayleigh Enhanced Optical Fiber

“…This phenomenon is known as fading, which degrades the sensing performance and has a more significant impact in low reflectivity conventional silica fibers. Therefore, it can be seen, the sensing fiber should have high reflectivity scattering points over the fiber distance for better sensing performance [27].…”

Probe pulse design in Brillouin optical time‐domain reflectometry

“…optical fibre sensing networks, which would bring great economic benefits [79,80]. In recent years, new coding sequences are also under investigation to further enhance the SNR of the systems.…”

“…Some researchers have deployed the differential (DPSK) and quadrature phase shift keying modulation formats into the BOTDA systems, to improve the spatial resolution of the system [78]. The deployment of high‐order modulation formats in distributed optical fibre sensing systems can also further promote the integration of optical fibre communication networks and optical fibre sensing networks, which would bring great economic benefits [79, 80]. In recent years, new coding sequences are also under investigation to further enhance the SNR of the systems.…”

Recent development in artificial neural network based distributed fiber optic sensors

“…is the peak BFS. Sweeping the continuous wave probe frequency, the BGS spectrum can be constructed [19]. The measured peak BFS determine the strain and/or temperature information over the sensing fiber.…”