A Multi-D-Shaped Optical Fiber for Refractive Index Sensing

Abstract

A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 μm depth, 250 μm width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 10−3–3.13 × 10−4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions.

High sensitivity SMS fiber structure based refractometer – analysis and experiment

“…Optical fiber based RI sensors have been studied extensively due to the advantages they offer, such as small size, immunity to electromagnetic interference, the potential for remote operation, high sensitivity, etc [1][2][3][4][5][6][7][8][9]. There are a number of ways to implement RI sensing, for example using a fiber Bragg grating (FBG) [1][2][3], long period grating [4], macro-bend singlemode fiber (SMF) [5], surface plasmon resonance [6], a Fabry-Perot interferometer [7], a multi-D-shaped optical fiber [8] or a singlemode-multimode-singlemode (SMS) fiber structure [9].…”

“…There are a number of ways to implement RI sensing, for example using a fiber Bragg grating (FBG) [1][2][3], long period grating [4], macro-bend singlemode fiber (SMF) [5], surface plasmon resonance [6], a Fabry-Perot interferometer [7], a multi-D-shaped optical fiber [8] or a singlemode-multimode-singlemode (SMS) fiber structure [9]. An SMS fiber structure based optical sensor has the additional advantages of low cost and ease of fabrication.…”

Overview of Micro- and Nano-Structured Surface Plasmon Resonance Fiber Sensors

“…The ability of multiple D-shaped zones in multi-mode fiber as a high sensitivity RI sensor was Fig. 16.7b [22]. When the number of D-shaped zones augments, the sensor resolution improves and then becomes worse after exhibiting the best value at five D-shaped zones in this work.…”

Experimental study of liquid refractive index sensing based on a U-shaped micro-fiber

“…One is to make micro-structure in the fiber such as Fabry-Perot cavity [6][7][8], fiber Bragg grating (FBG) [9][10][11] and optical fiber interferometer [12,13], with which physical quantity can be measured through the changes of optical signals' intensity, phase and wavelength. Another is to make the optical fiber the fiber carrying evanescent field by corroding or drawing a fiber, such as U-shaped fiber [14,15], D-shaped fiber [16][17][18][19] and taped-fiber. Their evanescent field is modulated by external media to measure.…”