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In this work, a new stable dual-wavelength erbium fiber ring laser is proposed and experimentally demonstrated. This configuration is made by creating two symmetrical laser cavities with similar optical power. This topology allows the performance of two laser emission lines in single-longitudinal mode and with a power instability lower than 0.23 dB, and an optical signal-to-noise ratio higher than 40 dB for all the emitted wavelengths. The sensing capability of the FBGs enables this source to be also used as sensor-network multiplexing scheme. The system offers a better stability and higher optical signal to noise ratios than similar configurations.

In this work, a new configuration of a multi-wavelength erbium fiber ring laser is proposed and demonstrated experimentally by introducing a feedback fiber loop in a fiber ring cavity. Four-wavelength laser emission lines were obtained simultaneously in single-longitudinal mode operation showing a power instability lower than 0.56 dB, and an optical signal-to-noise ratio higher than 50 dB for all the emitted wavelengths. The sensing capability of the FBGs gives this source the possibility to be also used as sensor-network multiplexing scheme. The system offers a better stability and higher optical signal to noise ratios than similar configurations.

In this work, a remote powered by light fiber optic switch is experimentally demonstrated. This fiber optic switch is powered by a photovoltaic power converter illuminated by a Raman laser working at distances up to 50 km. This switch is used to develop a remote resilient FBG multiplexing network interrogated by a commercial FBG interrogator. In the proposed set-up the switch selects the branch of the FBG network 50 km away in order to enable a two-way interrogation path for each sensor to prevent connection failures.

We propose a hybrid network that combine point and distributed Brillouin sensors in an architecture that also deploys remote distributed Raman amplification to extend the sensing range. A 46-km proof-of-concept network is experimentally demonstrated integrating point vibration sensors based on fiber-optic tapers, with distributed temperature sensing along the network bus. The sensor network with a double-bus topology offers a higher optical signal to noise ratio and dynamic range than a single-bus for intensity point multiplexed sensors. In this network, we include low-cost intensity sensors that are able to measure vibrations in the 0.01 to 50 Hz frequency range, which are important in the monitoring of large infrastructures such as pipelines.

We experimentally demonstrate a novel application of distributed fibre Raman amplification to a bus network for the wavelength multiplexing of optical sensors. Each sensor is uniquely identified by reflection from a fibre Bragg grating (FBG) and the distributed gain allows the number of sensors to be increased without using costly remote amplifiers. We show how the topology allows the received powers from the sensors to be equalised, even though only one Raman pump wavelength is used and we investigate how the performance depends on the launched pump power. The spectral filtering of the FBGs, combined with the distributed gain, jointly reduce the noise and we report measured signal to noise ratios.

A theoretical investigation on two techniques for the interrogation of fiber Bragg gratings (FBG) is reported. We compare two methods for decoding the Bragg wavelengths of gratings: the Fast Fourier Transform (FFT) processing and a parametric frequency estimation method called MUSIC. Results demonstrate that the second technique has advantages over the first one.

A novel method for interrogating interferometric sensors, based on analyzing the characteristics of the light expelled from a tilted fiber Bragg grating and captured by a photodetector linear array, is presented in the paper. Also a novel algorithm for the recovery of the measured information is proposed and its performance explored. It belongs to the parametric frequency estimation methods and is an adaptation of the MUltiple SIgnal Classification (MUSIC) algorithm. Finally an insight to the possibility of interrogating multiplexed interferometric sensors is given.