# Switchable Fiber Ring Laser Sensor for Air Pressure Based on Mach-Zehnder Interferometer
3918, Zona Playitas, Esnenda 22860, Mexico; [EMAIL_ADDRESS] 1  
Investigadoras e Investigadores por Mexico CONAHCYT, Consejo Nacional de Humanidades Ciencias y Tecnologias, Av. Insurgentes Sur 1582, Col. Credito Constructor, Benito Juarez 03940, Mexico 4  
Tecnologico Nacional de Mexico Campus Conkal, Avenida Tecnologico s/n Conkal, Merida 97345, Mexico; [EMAIL_ADDRESS] 1  
Facultad de Ingenieria y Ciencias, Universidad Autonoma de Tamaulipas, Ciudad Victoria 87149, Mexico; [EMAIL_ADDRESS] 1  
Jauregui-Vazquez  
1 Departamento de Ingenieria Electronica, Division de Ingenierias Campus Irapuato Salamanca, Universidad de Guanajuato, Carretera Salamanca-Valle de Santiago km 3.5 + 1.8 km, Salamanca 36885, Mexico; [EMAIL_ADDRESS] (A.P.-G.); [EMAIL_ADDRESS] (J.C.H.-G.); [EMAIL_ADDRESS] (J.C.H.-G.); [EMAIL_ADDRESS] (J.C.H.-H.); [EMAIL_ADDRESS] (J.M.S.-H.); [EMAIL_ADDRESS] (J.C.H.-L) 1  
Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (CICESE), Division de Fisica Aplicada-Dapartamento de Optica, Carretera Ensenada-Tijuana, No. 3918, Zona Playitas, Esnenda 22860, Mexico; [EMAIL_ADDRESS] 1  
Investigadoras e Investigadores por Mexico CONAHCYT, Consejo Nacional de Humanidades Ciencias y Tecnologias, Av. Insurgentes Sur 1582, Col. Credito Constructor, Benito Juarez 03940, Mexico 4  
Tecnologico Nacional de Mexico Campus Conkal, Avenida Tecnologico s/n Conkal, Merida 97345, Mexico; [EMAIL_ADDRESS] 1  
Facultad de Ingenieria Electronica, Division de Ingenierias Campus Irapuato Salamanca, Universidad de Guanajuato, Carretera Salamanca-Valle de Santiago km 3.5 + 1.8 km, Salamanca 36885, Mexico; [EMAIL_ADDRESS] (A.P.-G.); [EMAIL_ADDRESS] (J. Several fabrication techniques have been proposed to construct the in-line Mach-Zehnder interferometer, including the SMF-MMF-SMF structure [21; 22; 23; 24], multimode fiber-polarization-maintaining fiber Bragg grating-multimode fiber (MMF-PMFBG-MMF) [25], core offset [26], fiber tapering [27], photonic crystal fiber (PCF) configurations [28], twin-core fiber [29] and thin-core fiber modal interferometers [30; 31; 32; 33; 34; 35; 36; 37; 38; 39], and cascade fiber MZIs [40], among others. The sensor proposed by [PERSON], cascaded fiber MZIs, for simultaneous measurement of pressure and temperature, which consists of the cascade the splicing of two MZIs, gives an overview of the implementation of different types of fibers for the creation of the MZI, as well as tapers. The idea of operating with a modal interferometer using two types of fibers, differentiated by the diameter of their core, resulted in the TCFMI. This work differs from the one proposed by [PERSON], and presents a miniature fiber optic pressure sensor made from a Fabry-Perot cavity and a thin silica membrane fabricated via techniques involving fusion splicing and wet chemical etching, using a microscope to make the device splices, and seeks to make a small but more straightforward device to fabricate and manipulate that is low cost using a small length of thin-core fiber. In the literature, thin-core fibers have been employed for temperature [1; 30; 31], curvature [32; 33], refractive index [34], strain [30], gas pressure [35], liquid level [36], pH values [37], humidity [38], and ammonia gas [39]. [PERSON] et al. demonstrated a gas pressure sensor based on a twisted off-axis double strain and an air gap induced by a femtosecond laser in a commercial single-mode fiber (SMF), achieving a phase shift in the interferometer cladding arm. [PERSON] et al. proposed a Mach-Zehnder interferometer based on a twin-core fiber splicing a short section of dual-core fiber between two single-mode fibers. A microchannel was created to form an interferometer arm using a femtosecond laser to pierce one core of the dual-core fiber. In contrast, the core of the other fiber functioned as a reference arm.