In this paper, an all-fiber Mach-Zehnder interferometer (MZI) based on a non-zero dispersion-shifted fiber (NZ-DSF) is presented. The MZI was implemented by core-offset fusion splicing one section of a NZ-DSF fiber between two pieces of single mode fibers (SMFs). Here, the NZ-DSF core and cladding were used as the arms of the MZI, while the core-offset sections acted as optical fiber couplers. Thus, a MZI interference spectrum with a fringe contrast (FC) of about 20 dB was observed. Moreover, its response spectrum was experimentally characterized to the torsion parameter and a sensitivity of 0.070 nm/° was achieved. Finally, these MZIs can be implemented in a compact size and low cost.

In this letter, a curvature sensing setup based on a fiber ring laser containing a long-period fiber grating (LPFG) is presented. The LPFG operates as a wavelength selective filter and as a curvature sensing head. The LPFG consists of a periodically tapered fiber section written by a CO2-laser glass processing system. Experimental results show that by increasing the curvature values from 0 to 0.266 m-1, the laser wavelength emission shifts linearly from 1572 to 1560 nm, and a curvature sensitivity of -42.488 nm/m-1 is achieved. Additionally, the laser emission has a linewidth of 0.05 nm, a slope laser efficiency of 0.43single-mode suppression ratio (SMSR) of 60 dB. Finally, this fiber laser offers output power stability at room temperature, compactness, and robustness.

In this work an Intrinsic Fabry-Perot Interferometer (IFPI) based on an air-microcavity is presented. Here the air microcavity, with silica walls, is formed at a segment of a hollow core photonic crystal fiber (HCPCF), which is fusion spliced with a single mode fiber (SMF). Moreover, the spectral response of the IFPI is experimentally characterized and some results are provided. Finally, the viability to use the IFPI to implement a simple, compact size, and low cost refractive index sensor is briefly analyzed.

This manuscript experimentally validates a thin-film polymer and multimode fiber optic interaction-based low-cost optical fiber displacement sensor. The sensing setup is operated by deflecting a commercially Mylar® polymer film using multimode optical fiber. The sensor exhibits a higher sensitivity of 24nm/μm and resolution of 41.6nm. The sensor’s analyses also demonstrate good polynomial approximation, with a maximal adjusted square of R=0.9801, and high stability, in which minimal power (0.4dBHour) and wavelength (<2nm-Hour) variations are observed. Moreover, thermal experiments prove that the sensor has lower temperature traits (0.05μm/°C), and this parameter can be distinguished considering the wavelength shifting direction. The simplicity of the scheme, as well as the cost of the elements involved, make this technique a reliable alternative to detect micro-displacements.

This paper presents an axial strain laser sensing setup based on a core-offset Mach-Zehnder interferometer (MZI). The core-offset MZI was implemented by fusion splicing of three segments of single mode fiber and was used as wavelength selective filter and sensing head. The experimental results show that in the strain range from 0 to 333.333 με, the laser wavelength emission shifts linearly from 1554 to 1557 nm, achieving a strain sensitivity of 5.2332 pm µε⁻¹ and an R ² value of 0. 9988. The laser emission has a linewidth of 20 pm and a single-mode suppression ratio of 45 dB. Furthermore, the fiber laser offers output power stability at room temperature, compactness, and robustness.

Fiber laser sensors have been present for almost four decades as versatile sensing devices with a simple demodulation process, high sensitivity, and competitive resolution. This work discusses the most representative fiber laser sensor configurations employed for detecting critical parameters such as temperature, refractive index, and strain. However, essential information about other interesting parameters that have been measured is considered in this manuscript. Concurrently, the sensing elements and principle operation are described. Furthermore, these configurations are analyzed in terms of their principle of operation, sensitivity, gain medium, and wavelength operation range. According to the literature reviewed, fiber laser sensors offer the possibility of new interrogation techniques and simultaneous, independent detection. Considering interferometric fiber sensors, the fiber laser sensors offer high brightness, good output power, and high resolution. As a result, it is demonstrated that fiber laser sensors are a robust alternative for multiple sensing applications.