Waveguide optimization and its evaluation of a doped polymer optical fiber designed for visual detection of stress

Abstract

A fiber-optic strain sensor using a fluorophore-doped polymer optical fiber (POF) was fabricated at various waveguiding conditions. The effects attributed to each structural feature of the sensor were characterized by observing the sensor's response. Two fluorophores, Coumarin 540A and Rhodamine 6G, were used to dope the core and the cladding of a poly(methyl methacrylate)-based POF, respectively. Using doped POFs with different numerical apertures (NAs), the changes in the fluorophore peaks upon the application of stress were analyzed by applying macrobending(s) to the fiber. Although the sensor response did not show linearity with respect to the NA, it was found that the shape of the Coumarin 540A-attributed peak was a factor that represented the sensor's sensitivity. As a result, the double-cladding structure demonstrated its effectiveness in improving the stress sensitivity.

Mode-dependent dye absorption in phthalocyanine-doped acrylic optical fiber

“…Chemicals were purchased from the same supplier and purified in the same way as mentioned in previous reports. [20][21][22][23] In this study, we adopted four new phthalocyanine derivatives to be doped in the POF core. Their molecular structures are shown in Fig.…”

“…[13][14][15][16][17][18][19] We had previously reported POF sensors using fluorophores or dichroic dyes as dopants by using their absorption, emission, or radiative emission-absorption mechanism to produce improved sensing signals. [20][21][22][23] The problem is that all familiar dopants had absorption peaks in the range of 400-600 nm. This wavelength range does not reasonably match the transmission window of the POF, in particular, 650 nm.…”

“…24) For example, the Coumarin 540A and Rhodamine 6G used in our on-site visualization sensor have prominent absorption peaks around 420 and 550 nm, respectively. [20][21][22] The dichroic dye used in our strain-vector sensor has an absorption peak around 540 nm. 23) As long as we select acrylic polymers to synthesize the POF, 400-600 nm is absorbed significantly by the host polymer.…”

Nano‐dielectrics in biosystems

“…Engineering waveguides are usually built up with metallic plates, so that electromagnetic waves can be contained within the frames of metallic walls [78]. Or, they are made of a coaxial structure with two or three materials of different dielectric constants, that is, an optical fibre [79,80], so that electromagnetic signals can be reflected as much as possible at the material interface with less loss.…”