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

Abstract

A fiber optics structure for temperature measurement is presented and demonstrated. This structure is composed of segments of single mode fiber (SMF), no-core fiber (NCF), hollow core fiber (HCF), and cured polydimethylsiloxane (PDMS) which is inserted into the cavity of HCF. Owning to the high thermal expansion coefficient (TEC) and thermooptic coefficient (TOC) of PDMS, the optical path length and the effective refractive index (RI) all register much larger change, leading to the higher temperature sensitivity of the sensor. Simulation showed similar result with experiment. The temperature sensitivity of 580.6 pm/ C is achieved in the range of 28 C to 50 C. K E Y W O R D S modal interference, optical fiber, PDMS, sensor, temperature

A Review of Coating Materials Used to Improve the Performance of Optical Fiber Sensors

“…PDMS acts as the cladding and core at the same time. In order to give the fiber structure greater mechanical strength, a segment of hollow core fiber (HCF) filled with PDMS can be connected within the sensor [ 29 ]. In a similar fiber optic structure, two air chambers are added to both ends of the PDMS [ 30 ].…”

“… The sensors were filled with PDMS: ( a ) D-shaped fiber coated with PDMS [ 28 ]; ( b ) Hollow core fiber filled with PDMS [ 29 ]; ( c ) Hollow core fiber filled with air gap-PDMS-air gap [ 30 ]. …”

“…SMF Lead out SMF In the literature described above, PDMS was coated outside the cladding of the fiber as a coating material. In [28][29][30], PDMS was filled into the fiber as a special fiber core. As you can see in Figure 4, a section of the cladding and core of the standard single-mode fiber was removed, and the damaged area of the fiber was filled with PDMS with a certain thickness [28].…”

Application of microstructured fiber sensor in the field of temperature detection

“…Fiber optic temperature sensor has been widely used in the field of temperature measurement due to its good flexibility, resistance to electromagnetic interference and high sensitivity [1][2][3]. There are many kinds of optical fiber temperature sensors, and their sensing mechanism is not the same.…”

Dynamic Characterisation of Fibre-Optic Temperature Sensors for Physiological Monitoring

“…Many of the aforementioned techniques are performed as minimally invasive interventional procedures, in which highly miniaturised and flexible sensors are needed for integration into catheters, needles and guidewires. Fibre-optics can readily meet these requirements, and fibre-optic temperature sensing approaches include fibre Bragg gratings (FBG) and long period fibre gratings (LPFG) [ 32 , 33 , 34 , 35 , 36 , 37 ]; polymer-based [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ], inorganic [ 48 , 49 , 50 ] and microbubble-based [ 51 ] Fabry–Pérot (FP) cavities; multimode interference (MMI) segments [ 52 , 53 , 54 , 55 , 56 , 57 , 58 ]; infiltrated photonic crystal fibre and hollow-core fibre [ 59 , 60 ]; fluorescence-based methods [ 22 , 23 , 24 ]; and sensors based on polymer optical fibres [ 61 , 62 , 63 , 64 ]. The wide variety of geometries and materials employed in these sensors can lead to very different response times, from sub-millisecond for a silicon FP cavity [ 50 ] to hundreds of milliseconds for packaged FBGs [ 18 , 36 ].…”