Silvia Diaz

A High-Performance Optical Time-Domain Brillouin Distributed Fiber Sensor

A novel configuration for a Brillouin distributed fiber sensor based on Brillouin optical time-domain analysis is proposed. This configuration eliminates many intensity noise issues found in previous schemes. Resolution of 7 m all over a 47 km single-mode fiber was achieved and resolution down to 30 cm in a few kilometer fiber. Noise reduction makes possible measurements with a 16 times averaging.

Long-range hybrid network with point and distributed Brillouin sensors using Raman amplification.

We propose a novel concept for hybrid networks that combine point and distributed Brillouin sensors in a cost-effective 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 Bragg gratings and tapers with distributed temperature sensing along the network bus. In this network the use of Raman amplification to compensate branching and fiber losses provides a temperature resolution of 0.7 degrees C and 13 m. Moreover, it was possible to obtain good optical signal to noise ratio in the measurements from the four point vibration sensors that were remotely multiplexed in the network. These low-cost intensity sensors are able to measure vibrations in the 0.1 to 50 Hz frequency range, which are important in the monitoring of large infrastructures such as pipelines.

Resilient Amplified Double-Ring Optical Networks to Multiplex Optical Fiber Sensors

In this paper, we report the experimental demonstration of an amplified optical fiber double-ring network for the multiplexing of sensors. The network is designed to be inherently resilient to fiber failures because it enables simultaneous interrogation of all the optical fiber sensors using both rings. We demonstrate the feasibility of so-called ldquodedicated protectionrdquo for fiber optic intensity sensors. Raman amplification is used to overcome the losses of the couplers used in the rings, providing power transparency. In this novel configuration, Raman pumping is activated only when a fiber failure occurs. We demonstrate how the topology allows the received powers from the sensors to be equalized.

Resilient long-distance sensor system using a multiwavelength Raman laser

This paper shows a long-distance remote sensing system using a multiwavelength Raman laser. The sensor network is based on a 50 km long standard single-mode fiber (SMF) and is composed of a simple cavity based on a loop mirror and four fiber Bragg gratings (FBGs) arranged in a star configuration. FBGs are used for both the sensing function and the selection of the lasing wavelengths. The system is designed to be inherently resilient to fiber failures. The multiwavelength laser has been characterized for temperature measurements showing a good stability performance.

Comparison of the Stability of Ring Resonator Structures for Multiwavelength Fiber Lasers Using Raman or Er-Doped Fiber Amplification

An experimental comparison of the stability performance of two multiwavelength lasers, based on either an erbium-doped fiber or Raman amplification, is reported. Both systems employ fiber Bragg gratings to select the operating wavelengths within the resonant ring cavity. The aim of this study is to compare the output power stability of the lasers and also their optical SNR ratios.

Dual-wavelength single-longitudinal-mode erbium fiber laser for temperature measurements

Abstract. A dual-wavelength erbium fiber laser with single-longitudinal-mode characteristic is proposed and demonstrated. The system uses a 7-m-long highly doped erbium-doped fiber as the primary gain medium while two fiber Bragg gratings (FBGs) act as a wavelength selection mechanism. The sensing capability of the FBGs gives this source the possibility to be also used in a dual-sensor multiplexing scheme. The system is very stable and suitable for sensor multiplexing.

Wavelength-division-multiplexed distributed fiber Raman amplifier bus network for sensors

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.

Stable Dual-Wavelength Erbium Fiber Ring Laser With Optical Feedback for Remote Sensing

In this paper, a new stable dual-wavelength erbium fiber ring laser for remote temperature measurements is proposed and experimentally demonstrated. The sensing element is composed of two fiber Bragg gratings and sensor interrogation is achieved with a dual-wavelength erbium fiber ring laser. 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 (SLM) and with power instability lower than 0.23 dB, and an optical signal-to-noise ratio higher than 30 dB for all the emitted wavelengths. The application of this system for remote temperature measurements has been demonstrated even though the SLM regime cannot be maintained.

High performance Brillouin distributed fibre sensor

We propose a novel configuration for a Brillouin distributed sensor based on Brillouin optical time domain analysis. This new configuration eliminates many intensity noise issues found in previous schemes. Resolution of 3.5 m all over a 47 km single-mode fibre was achieved and resolution down to 30 cm in a few kilometre fibre. Noise reduction makes possible measurements with a 16 times averaging.

46-km-Long Raman Amplified Hybrid Double-Bus Network With Point and Distributed Brillouin Sensors

We experimentally demonstrate a 46-km hybrid network that combine point and distributed Brillouin sensors. The proposed sensor network multiplexes low-cost intensity point sensors based on fiber-optic tapers, which are able to measure vibrations in the 0.01 to 50 Hz frequency range. The sensor network with a double-bus is a low noise configuration, which offers a higher optical signal to noise ratio and dynamic range than a single-bus. Thus, the number of sensors to be multiplexed could increase or we could reach further distances. The system also deploys remote distributed Raman amplification to extend the sensing range.