A sensing system for micro-displacement measurement based in a suspended-core fiber Sagnac interferometer is presented. The suspended-core fiber characterization was made through the use of an optical backscatter reflectometer, screening its multimodal and birefringent behavior. Its sensitivity to displacement measurements is shown to be due only to birefringence, being that core-cladding mode coupling is negligible. High precision ($\sim 0.45\mathrm{\mu m}$) was obtained using three different measurement instruments, showing an extremely high stability and high insensitivity to temperature, demonstrating that the sensing system has the ability for low cost applications.

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.

A real-time switchable and reconfigurable multiwavelength laser has been experimentally carried out. The laser cavity is based on a random distributed mirror and a novel real-time reconfigurable filter mirror structure. The proposed laser has been demonstrated to generate any combination of wavelengths at the 50 and 100 GHz International Telecommunications Union (ITU) grids specifications. By simultaneously using Er-doped fiber and Raman amplification, a 15 nm wide lasing window at the C band can be utilized to create up to 18 different lasing wavelengths into the ITU grid that can be switched automatically and in real time when desired.

In this paper, a theoretical and experimental study of two interferometric sensor multiplexing schemes has been carried out by means of the fast Fourier transform (FFT) analysis. This study addresses one of the main drawbacks of photonic crystal fiber (PCF) sensors, that is, its multiplexing capability. Using a commercial optical interrogator combined with a simple FFT measurement technique, the simultaneous real-time monitoring of several PCF sensors is achieved. A theoretical analysis has been performed where simulations matched with the experimental results. For the experimental verification, highly birefringent (HiBi) fiber sections that operated as sensing elements were multiplexed and tested in two configurations. Due to the FFT analysis, both multiplexing schemes can be properly interrogated by monitoring the FFT phase change at the characteristic spatial-frequency of each sensor. For this purpose, a commercial interrogator and a custom Matlab program were used for computing the FFT and for monitoring the FFT phase change in real time (1 Hz).

In this paper, a random distributed feedback fiber laser is proposed as a multiplexing scheme for ultralong range measurements (up to 200 km). Optical fiber sensors are time and wavelength multiplexed overcoming one of the main limitations of long-range sensing setups, which is their limited multiplexing capability. The direct modulation of the laser's cavity allows the interrogation of sensors by measuring the reflected power for different wavelengths and distances. Fiber Bragg gratings placed at different fiber locations and wavelengths have been interrogated in two different sensor networks. In addition, in order to improve the performance of the system, some features have been analyzed.

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.