Óptica Pura y Aplicada through the purple filter

En sus cincuenta y cinco años de historia, la revista insignia de la sociedad científica SEDOPTICA ha asistido, junto a sus socios y socias, a la transformación de un país. En este artículo analizamos cómo valores como la igualdad entre hombres y mujeres se han reflejado en la revista a lo largo de este tiempo.During its fifty-five years of history, the flagship journal of the scientific society SEDOPTICA has, together with its members, witnessed the transformation of a country. In this article we analyse how values such as equality between men and women have been reflected in the magazine over this time.Sección Deptal. de Óptica (Óptica)Fac. de Óptica y OptometríaTRUEpu

Robust fiber-optic sensor networks

The ability to operate despite failure will become increasingly important as the use of optical sensor networks grows, and the amount of sensing information to be handled by a sensor network is increasing, especially for safety and security applications. In this review, the four categories of protection to allow service to be reestablished after a failure (dedicated/shared and line/path) are thoroughly discussed. This paper also presents an overview of the most representative robust fiber-optic sensor systems, discussing their schemes, pros and cons.The authors are grateful to the Spanish Government project TEC2010-20224-C02-01

Single longitudinal mode lasers by using artificially controlled backscattering erbium doped fibers

In this work, we propose and experimentally demonstrate a new distributed short linear cavity fiber laser. At one of the cavity ends, fabricated by a commercial femtosecond fiber laser chirped pulse amplifier, an artificially controlled backscattering erbium doped fiber section has been connected. This distributed reflector acts also as a saturable absorber, leading to the generation of tunable and switchable single longitudinal-mode laser emissions. The distributed reflector consists of 9 micro-drilled sections of about 1cm each one and randomly spread throughout 2 meters of highly doped erbium fiber. The total length of the fiber laser is 9.5 m and the laser shows a single mode behavior at all the emitted wavelengths. Using this new kind of reflecting saturable absorber, single and multiple single-mode emissions can be obtained. The achieved laser presents a pump threshold as low as 45 mW and shows up to 8 different single-mode emission lines with an optical signal to noise ratio of 45dB.This work was supported in part by the MINECO/AEI (Ministerio de Economía y Competitividad/Agencia Estatal de Investigación), Spain, under Grant TEC2016-76021-C2-1-R, Grant TEC2016-76021-C2-2-R, and Grant PID2019-107270RB; in part by the Ministerio de Educación, Cultura y Deporte of Spain under Grant FPU2018/02797, and in part by the Projects for Young Researches UPNA 2019 (Universidad Publica de Navarra) and FEDER Funds (European Regional Development Fund)