Truly remote fiber optic sensor networks

Abstract

An overview of truly remote fiber optic sensors is presented in this work. It starts with a brief introduction of fiber optic sensor networks, showing their advantages and multiple applications. Then, the definition of truly remote networks is provided, and their main challenges discussed, such as increasing the sensing distance and the number of sensors interrogated. Several multiplexing techniques have been compared, such as wavelength, time and coherence division multiplexing. In relation to this, the most recent works showing multi wavelength fiber lasers for wavelength division multiplexing have been grouped and their versatility analyzed. Finally, recent and relevant truly remote fiber optic networks have been gathered and some of the most representative schemes explained in detail, comparing their multiplexing capability and the remoteness of the monitored sensors. Random distributed feedback fiber lasers form part of a number of these schemes, proving the suitability of this type of lasers for their use in ultra-long truly remote sensing applications.

Multiplexed Passive Optical Fiber Sensor Networks for Water Level Monitoring: A Review

“…There are various criteria to classify the type of sensor networks: the network topology (bus or star); transducing approach (intrinsic or extrinsic); and modulation mechanism (intensity, frequency, phase, and so on) [14]. On the other hand, the OFS networks can be categorized into two different groups according to the spatial distributions of the measurement points, as shown in Figure 2 the Fabry-Perot interferometer (FPI) [13] employed as one of the discrete sensors.…”

“…There are various criteria to classify the type of sensor networks: the network topology (bus or star); transducing approach (intrinsic or extrinsic); and modulation mechanism (intensity, frequency, phase, and so on) [14]. On the other hand, the OFS networks can be categorized into two different groups according to the spatial distributions of the measurement points, as shown in Figure 2 The distributed sensors perform continuous sensing within a specific area/range at relatively high spatial resolutions that are realized by a Rayleigh-, Brillouin-, or Raman scattering-based optical time-domain reflectometer (OTDR) [6,11,15], which is the basic mechanism of fault localization in fiber optic communications.…”

“…In the quasi-distributed OFS network, the multiplexing allows a single interrogation system (i.e., a single optical source and a single detector) to support multiple SUs, enhancing the system performance, as well as the practicability (in terms of install and operation costs/efforts) [14,30]. As summarized in Table 2, various multiplexing techniques have been proposed for the OFS network with discrete SUs [31][32][33][34][35][36][37][38][39][40][41][42][43].…”

“…Then, the optical signals from the multiple SUs are multiplexed, as shown in Figure 3a, which provides good scalability and network transparency. The implementation of the WDM system relies on the wavelength-independent (i.e., color-free) optical sources that are realized by arrayed DFB-LD [45], multimode Fabry-Perot laser [46], amplified spontaneous emission (ASE) light [47], multi-wavelength fiber lasers [14], and wavelength tunable laser sources [48,49]. The WDM can be further divided into two groups according to the channel spacing: (i) coarse WDM (CWDM) and (ii) dense WDM (DWDM).…”

Ultrafast convergent power-balance model for Raman random fiber laser with half-open cavity

“…For the distributed amplification, the power distribution is the focus of consideration, and for point-sensing system it could be the threshold. In fact, a model that can quickly calculate these features in a half-open cavity RRFL is highly desired for most applications [20,21], as it would help to the system designer to grip the major outcome without going through all the details. The first analytical RRFL model with formulas describing power features was proposed in Ref.…”