Montserrat Fernandez-Vallejo

Internal modulation of a random fiber laser

A characterization of a modulated random mirror laser has been experimentally carried out. Unlike conventional internally modulated fiber lasers, no distortion of the modulating frequency or self-mode-locking effects were measured. The behavior of the laser using pulsed and analog modulation up to 12 GHz is shown.

Stabilization of Dual-Wavelength Erbium-Doped Fiber Ring Lasers by Single-Mode Operation

In this work, a novel single-longitudinal-mode (SLM) dual-wavelength laser configuration is proposed and demonstrated. This laser is based on ring resonators, and employs fiber Bragg gratings to select the operation wavelengths. It includes a short piece of highly doped Er-fiber that acts as the active medium. The stable SLM operation is guaranteed when the two lasing channels present similar output powers. This behavior is shown for different pump powers.

Suspended-core fiber Sagnac combined dual-random mirror Raman fiber laser

In the present work, a multiwavelength fiber laser based in the combination of a double-random mirror and a suspended-core Sagnac interferometer is presented. The double-random mirror acts by itself as a random laser, presenting a 30dB SNR, as result of multiple Rayleigh scattering events produced in the dispersion compensating fibers by the Raman amplification. The suspended-core fiber Sagnac interferometer provides the multi peak channeled spectrum, which can be tuned by changing the length of the fiber. The result of this combination is a stable multiwavelength peak laser with a minimum of ~25dB SNR, which is highly sensitive to polarization induced variations.

Stability Comparison of Two Ring Resonator Structures for Multiwavelength Fiber Lasers Using Highly Doped Er-Fibers

An experimental comparison of stability between two different fiber laser topologies is carried out. The lasers are based on ring resonators that include highly doped Er-fibers. Both topologies use fiber Bragg grating reflectors in order to select the emission wavelengths. The experimental results confirms that the novel topology based on fiber optic circulators arranged in a hybrid serial-parallel configuration offers better stability and a higher optical signal-to-noise ratio (OSNR) than the simpler one based on a parallel configuration.

Optical Fiber Networks for Remote Fiber Optic Sensors

This paper presents an overview of optical fiber sensor networks for remote sensing. Firstly, the state of the art of remote fiber sensor systems has been considered. We have summarized the great evolution of these systems in recent years; this progress confirms that fiber-optic remote sensing is a promising technology with a wide field of practical applications. Afterwards, the most representative remote fiber-optic sensor systems are briefly explained, discussing their schemes, challenges, pros and cons. Finally, a synopsis of the main factors to take into consideration in the design of a remote sensor system is gathered.

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.

Remote (250 km) Fiber Bragg Grating Multiplexing System

We propose and demonstrate two ultra-long range fiber Bragg grating (FBG) sensor interrogation systems. In the first approach four FBGs are located 200 km from the monitoring station and a signal to noise ratio of 20 dB is obtained. The second improved version is able to detect the four multiplexed FBGs placed 250 km away, offering a signal to noise ratio of 6–8 dB. Consequently, this last system represents the longest range FBG sensor system reported so far that includes fiber sensor multiplexing capability. Both simple systems are based on a wavelength swept laser to scan the reflection spectra of the FBGs, and they are composed by two identical-lengths optical paths: the first one intended to launch the amplified laser signal by means of Raman amplification and the other one is employed to guide the reflection signal to the reception system.

L-Band Multiwavelength Single-Longitudinal Mode Fiber Laser for Sensing Applications

In this work, a novel single-longitudinal-mode (SLM) four-wavelength laser configuration for sensing applications in the L-band is proposed and experimentally demonstrated. The sensor system presented here is based on ring resonators, and employs fiber Bragg gratings to select the operation wavelengths. The stable SLM operation is guaranteed when all the lasing channels present similar output powers. It is also experimentally demonstrated that when a SLM behavior is achieved, lower output power fluctuations are obtained. Characterization of the lasing structure for temperature sensing is also shown.

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.

Ultra-Long Laser Systems for Remote Fiber Bragg Gratings Arrays Interrogation

This letter proposes and demonstrates two, 100 and 200 km, long distance fiber laser systems for fiber Bragg grating (FBG) sensors multiplexing. The first system is based on a fiber ring laser and reaches 100 km, whereas the second one is composed by a random fiber laser with a reach of 200 km. Both of them are able to multiplex 11 FBGs. In addition, because of the mode operation of the systems, they are low noise configurations.