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A simple fabrication method of micro/nano-optical fibers (MNOFs) based on near-field melt electrospinning (NMES) is proposed in this Letter. Single fibers with diameters ranging from 500 nm to 6 μm were directly written by near-field electrospinning of molten poly(methyl methacrylate) (PMMA). The morphology and transmission characteristics of single PMMA MNOFs were experimentally measured. The results showed that PMMA MNOFs have the advantages of smooth surfaces, uniform diameters, and low loss. As an example of one-step fabrication for MNOF devices, a planar helical MNOF structure was directly written and optically characterized. To demonstrate the versatility of the NMES process, in combination with the microfluidic technique, a liquid refractive index-sensing chip was fabricated and tested. Our results demonstrate that the proposed fabrication method has strong potential in the direct writing of patterned optical devices and heterogeneous integrated devices.

Polymer-derived ceramic (PDC) is considered an excellent sensing material for harsh environments such as aero-engines and nuclear reactors. However, there are many inherent limitations not only in pure PDC but also in its common fabrication method by furnace thermolysis. Therefore, this study proposes a novel method of rapid in situ fabrication of PDC composite thin-film sensors by laser pyrolysis. Using this method with different fillers, a sensitive PDC composite film layer with high-quality graphite can be obtained quickly, which is more flexible and efficient compared to the traditional furnace thermolysis. Furthermore, this study analyzes the reaction differences between laser pyrolysis and furnace thermolysis. The laser pyrolysis method principally produces β-SiC and enhances the graphitization of amorphous carbon, while the degree of graphitization by furnace thermolysis is low. In addition, it is capable of rapidly preparing an insulating PDC composite film, which still has a resistance of 5 MΩ at 600 °C. As a proof of this method, the PDC composite thin-film strain sensors are fabricated in situ on nickel alloys and aluminum oxide substrates, respectively. The sensor fabricated on the nickel alloy with a high gauge factor of over 100 can be used in high-temperature environments below 350 °C without the protection of an oxidation-resistant coating. In this way, the approach pioneers the in situ laser fabrication of functional PDC films for sensors, and it has great potential for the in situ sensing of complex curved surfaces in harsh environments.