Optical fiber flowmeter based on a single mode-multimode-single mode structure

Single mode-Multimode-Single mode (SMS) sensors have been attracted a relevant attention because of their simple manufacturing, capability sensing different quantities, and enhanced sensitivity compared to the most common fiber optic sensor represented by Fiber Bragg Gratings (FBGs). Moreover, SMS exhibit blue-shift strain, opposite FBGs, making them suitable in applications where strain-temperature cross-sensitivity may be an issue. are made splicing short multimode, preferably two or quasi two-mode, optical jumper between single pigtails. The interference modes propagating at phase velocities produces spectral pattern that shifts with temperature, strain any perturbation difference among modes. In this paper we review main features SMSs as temperature present potential biomedical application all-fiber flowmeter based on hot-wire principle: fiber-coupled laser source 980 nm is used controllable heating that, when immersed fluid flow, converts variation, caused heat removal, into wavelength shift transmitted spectrum. Thermal characterization proof-of-concept experiments show feasibility functionality provide outlook possible developments applications.