Fabrication of highly stable microfiber structures via high-substituted hydroxypropyl cellulose coating for device and sensor applications

Abstract

We demonstrate a cost-effective approach to fabricate stable microfiber structures taking advantage of high-substituted hydroxypropyl cellulose (H-HPC) coating. The microfibers are bent, twisted, or coiled to form desired geometries, and then the segments in contact are coated to resist the existing bending or twisting stresses to stabilize the structures. Coated devices including a twisted Sagnac interferometer, a ring resonator, and a Fabry-Perot cavity have been exhibited. Measured result suggests that the coated structures are highly stable over 20 days. The thin, low-index coating material allows for a strong evanescent-field interaction between the mode field and ambient solution. As an example, the coated twisted Sagnac interferometer can act as a refractive-index sensor with a sensitivity as high as 2600 nm/RIU. The present technique is greatly beneficial for long-term working of microfiber devices and sensors and offers a possible approach for the development of integrated microphotonic devices and platforms.

A Comprehensive Review of Optical Fiber Refractometers: Toward a Standard Comparative Criterion

“…Although there is an exceptional case of low sensitivity, they show sensitivities from thousands to tens of thousands of nm per RIU, with a record sensitivity of 24 373 nm per RIU . Regarding the Q factor, the best value has been obtained with a coated twisted Sagnac interferometer: 25 833, which permits obtaining a record FOM of 43 333 in the water range.…”

Optical Refractive Index Sensors with Plasmonic and Photonic Structures: Promising and Inconvenient Truth

“…Twisted micorfibre is another effective way for SI construction [90,91,478]. For example, as shown in Figure 10, panel E, b, a twisted micorfibre SI is composed of a fibre loop and a twisted micorfibre.…”

Optical microfiber or nanofiber: a miniature fiber-optic platform for nanophotonics

“…While a bare MNF decreased with a rate of ∼0.2 dB/h in optical transmittance, the embedded MNF remained basically unchanged within 6 days. After that, a variety of low-loss, low-refractive-index materials have been employed for MNF packaging, including polydimethylsiloxane (PDMS) [243–247] , Teflon [248,249] , hydrophobic aerogel [250] , ultraviolet (UV) curable polymer [251,252] , and high-substitution hydroxypropyl cellulose [253,254] . Figure 13(a) illustrates a silica MNF embedded in a PDMS film [247] , showing the advantages of a small footprint, high flexibility, and conformability to non-flat surfaces (e.g., a human hand).Air-tight sealingSealing the MNFs inside an air-tight box has also been commonly adopted.…”