Photonic sensors

This invited featured paper offers a Doctrinal Conception of sensing using Light (SuL) as an “umbrella” in which any sensing approach using Light Sciences and Technologies can be easily included. The key requirements of a sensing system will be quickly introduced by using a bottom-up methodology. Thanks to this, it will be possible to get a general conception of a sensor using Light techniques and know some related issues, such as its main constituted parts and types. The case in which smartness is conferred to the device is also considered. A quick “flight” over 10 significant cases using different principles, techniques, and technologies to detect diverse measurands in various sector applications is offered to illustrate this general concept. After reading this paper, any sensing approach using Light Sciences and Technologies may be easily included under the umbrella: sensing using Light or photonic sensors (PS).This work has been supported by Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (Grant PID2019-107270RB-C21 funded by MCIN/AEI /10.13039/501100011033) and also TeDFeS Project (grant RTC-2017-6321-1) co-funded by European FEDER funds ( as a way of making Europe)

Sensing using light: a key area of sensors

This invited featured paper offers a Doctrinal Conception of sensing using Light (SuL) as an "umbrella" in which any sensing approach using Light Sciences and Technologies can be easily included. The key requirements of a sensing system will be quickly introduced by using a bottom-up methodology. Thanks to this, it will be possible to get a general conception of a sensor using Light techniques and know some related issues, such as its main constituted parts and types. The case in which smartness is conferred to the device is also considered. A quick "flight" over 10 significant cases using different principles, techniques, and technologies to detect diverse measurands in various sector applications is offered to illustrate this general concept. After reading this paper, any sensing approach using Light Sciences and Technologies may be easily included under the umbrella: sensing using Light or photonic sensors (PS).This work has been supported by Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (PID2019-107270RB-C21/AIE/10.13039/501100011033) and also TeDFeS Project (RTC-2017-6321-1) co-funded by European FEDER funds

Virtual long-period gratings

A theoretical prediction of a new fiber grating structure is presented. This new device is achieved when a high-birefringence fiber is heavily twisted. It behaves like a long-period grating, but its spectral response can be controlled with the input state of polarization of the light. Since there is no permanent index change, but the index change is instead a product of the polarization evolution along the fiber, this device is called a virtual long-period grating

Brillouin distributed fiber sensors: an overview and applications

A review focused on real world applications of Brillouin distributed fiber sensors is presented in this paper. After a brief overview of the theoretical principles, some works to face the two main technical challenges (large dynamic range and higher spatial resolution) are commented. Then an overview of some real and on-field applications is done.This work has been supported by the Spanish TEC2010-20224-C02-02 Project

Pulsed wavelength-tunable Brillouin fiber laser based on a Fourier-domain mode-locking source

In this work, a pulsed wavelength-tunable Brillouin fiber laser based on a Fourierdomain mode-locking (FDML) source with a repetition rate of 4.2 kHz is presented. The tunable Brillouin laser is formed by a fiber-ring cavity (for the Stokes signal amplification) within a primary fiber-ring cavity for generating an FDML signal. The primary cavity is formed by an erbium-doped fiber amplifier and a fiber Fabry-Perot filter (FFP-F) as the gain medium and the tunable optical bandpass filter, respectively. A spectral laser tuning range of 2.54 nm centered in 1531 nm was achieved by adjusting the offset voltage of the FFP-F, while a variation, from 0.282 to 0.462 nm, on the Brillouin linewidth of the laser was achieved by setting the amplitude of a modulation signal applied in the FFP-F. A laser pulsewidth of 6.50 us was measured, and an output power of -7 dBm was achieved.This work was supported by the Spanish government through project TEC2010-20224-C02-C02

Optica Integrada: diseño de commutadores de acoplo direccional por método del índice efectivo

Se explica cómo diseñar conmutadores electroópticos integrados de acoplo direccional siguiendo el método de índice efectivo

Laser-induced breakdown spectroscopy: fundamentals, applications, and challenges

Laser-induced breakdown spectroscopy (LIBS) is a technique that provides an accurate in situ quantitative chemical analysis and, thanks to the developments in new spectral processing algorithms in the last decade, has achieved a promising performance as a quantitative chemical analyzer at the atomic level. These possibilities along with the fact that little or no sample preparation is necessary have expanded the application fields of LIBS. In this paper, we review the state of the art of this technique, its fundamentals, algorithms for quantitative analysis or sample classification, future challenges, and new application fields where LIBS can solve real problems

Reflection-based lab-in-fiber sensor integrated in a surgical needle for biomedical applications

Recently, lab-in-fiber (LIF) sensors have offered a new paradigm in many different scenarios, such as optofluidics, due to their ability to integrate different multiphysics sensor elements in a small space. In this Letter, the design and manufacture of a multiparameter sensing device is proposed, through the combination of an in-fiber air microcavity and a plane-by-plane fiber Bragg grating (FBG). The reflection-based sensor, with a length of less than 300 µm, is located at the end of a single-mode fiber and integrated into a surgical needle for exploitation in biomedical applications. Here we present the first (to our knowledge) ultra-short LIF sensor reported under the "touch and measure" approach. In this first prototype, the detection of axial tensile strain (6.69pm/µe in air cavity) and surrounding refractive index (11.5 nm/RIU in FBG) can be achieved simultaneously.Agencia Estatal de Investigación (PID2019-107270RB-C21, TEC2016-76021-C2-2-R); Ministerio de Educación, Cultura y Deporte (FPU2018/02797)

Slit beam shaping technique for femtosecond laser inscription of symmetric cladding waveguides

In recent years, the Industry 4.0 paradigm has gained special relevance, focused on the integration of smart structures to increase the efficiency of processes. Photonics, with laser advanced manufacture and light-based sensors, can offer great possibilities in this field. Within advanced manufacturing, femtosecond lasers allow inscribing different optical structures. Waveguides are one of the most widely used structures in photonic sensors. This work proposes the design, simulation and manufacture of symmetric cladding waveguides in optical fibers using the slit beam shaping technique. Cladding waveguides characterized by their low losses (0.21 dB/cm), quasi?step-index refractive index profile, and circular cross-section are used to couple evanescent light from the core of a single-mode fiber to each of the four cores of a multicore fiber.This work has been supported by the Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (PID2019-107270RB- C21), the Ministerio de Educación, Cultura y Deporte of Spain (PhD grant FPU2018/02797), and FEDER funds

Optical strain gauge with high spatial resolution

A technique to enhance the spatial resolution of typical fiber Bragg grating–based strain gauges has been experimentally verified in this study. Just analyzing the intensity of the reflection spectrum of a sampled fiber Bragg grating, its inner deformation profile has been obtained with a spatial resolution of Formula L<1mm. The proposed method employs a synthesis algorithm to retrieve the longitudinal axis strain profile of a sampled fiber Bragg grating glued to an asymmetric plate. The achieved experimental results have been compared to the mechanical simulations of the employed plate, exhibiting a good response even without compensating the residual stress provoked during the installation process.This study was supported by the project TEC2010-20224-C02-02 and grant AP2009-1403