Temperature cross-sensitivity characteristics of singlemode–multimode–singlemode fiber structure

Abstract

The temperature cross-sensitivity characteristics of a singlemode-multimode-singlemode (SMS) fiber structure packaged by a shell are studied both theoretically and experimentally. By theoretical investigation, we found that the temperature sensitivity of a SMS structure is mainly determined by the thermo-optic effect (TOE) of the cladding of the multimode fiber (MMF). Meanwhile, the TOE of the MMF core, thermal expansion effects (TEEs) of the MMF core, and the packaging material also influence the ultimate sensitivity, and the magnitude of their effects depends on the refractive index of the MMF cladding. Among them, the TEE of the packaging material, inducing an axial strain, is considered to be the second main factor. A temperature sensor based on a packaged SMS structure is designed and investigated to experimentally verify the theoretical findings. The experimentally measured temperature sensitivity of the sensor is -453.4 pm/°C, which agrees well with the theoretical prediction.

Optical fiber temperature sensor based on modal interference in multimode fiber lengthened by a short segment of polydimethylsiloxane

“…This value is similar to the simulated result and much higher than the temperature coefficient of pure silica . Meanwhile, it is comparable to the temperature sensitivity of the liquid‐encapsulated modal interferometer …”

“…After the high‐profile single‐mode‐multimode‐single‐mode (SMS) structure, a number of configurations have been implemented as temperature sensor in recent years . To increase the sensitivity, some progress is made to the sensor structure by building high thermal expansion coefficient (TEC) skeleton, bending the fiber, and tubing the sensor with high TOC liquid . All the purposes are to increase the TOC and TEC of the guided modes that participate in the modal interference for sensing.…”

Improvement of Temperature Performance of Singlemode-Multimode-Singlemode Fiber Structure

“…In this work, an SMS fiber temperature sensor is designed. The production and measurement process of the temperature response of the sensor shown in Figure 1 are the same as our previous work [ 15 ]. The SMF and MMF are the standard SMF-28 (Corning Inc., New York, NY, USA) and commercialized no-core fiber (NCF, Prime Optical Fiber Co., Taiwan, China), respectively.…”

“…In our previous work [ 15 ], glycerol–water mixture (3:1 volume mixture) with a RI of 1.43 and a TOC of −1.827 × 10 −4 /°C served as MMF cladding. While in this paper, distilled water with a RI of 1.32 and a TOC of −1.5 × 10 −4 /°C serves as the MMF cladding.…”

“…Nonetheless, the temperature properties of the SMS fiber structure presented by the aforesaid studies are only for the cases with some fixed parameters. In our previous works [ 15 ], the temperature cross-sensitivity characteristics of SMS fiber structure packaged by a shell were studied. But the absorption characteristic of the MMF cladding was not considered, the effect of MMF core diameter on the temperature characteristics of the SMS fiber structure was not studied, and the temperature stability of the non-temperature sensor was not discussed either.…”