A novel high-sensitive fiber-optic Fabry-Perot sensor with parallel polymer-air cavities based on Vernier effect was proposed and demonstrated for simultaneous measurement of pressure and temperature. The sensor is composed of two parallel Fabry-Perot cavities both are fabricated by splicing a section of silica tube to the single-mode fiber. One cavity is filled with polydimethylsiloxane, and the other cavity is filled with a thin layer of ultraviolet glue at the end-face of silica tube, ensuring that the free spectrum ranges of two Fabry-Perot cavities are similar and generate the Vernier effect. The Fabry-Perot interferometer filled with polydimethylsiloxane was found to be sensitive to pressure as well as temperature, whereas the Fabry-Perot interferometer filled with a thin layer of ultraviolet glue was sensitive to pressure only. Owing to the different features of two Fabry-Perot interferometers, the sensor achieved simultaneous measurement of pressure and temperature. Combined with Vernier effect, the sensor provided a pressure sensitivity of −36.93 nm/MPa and a temperature sensitivity of 10.29 nm/°C, respectively. The sensor has exhibited potential applications in fields of medical diagnostics, environmental monitoring, and biological sensing.

A compact fiber-optic temperature sensor with hybrid interferometers enhanced by the harmonic Vernier effect was proposed, which realized 36.9 times sensitization of the sensing Fabry-Perot interferometer (FPI). The hybrid interferometers configuration of the sensor consists of a FPI and a Michelson interferometer. The proposed sensor is fabricated by splicing the hole-assisted suspended-core fiber (HASCF) to the multi-mode fiber fused with the single-mode fiber, and filling polydimethylsiloxane (PDMS) into the air hole of HASCF. The high thermal expansion coefficient of PDMS improves the temperature sensitivity of the FPI. The harmonic Vernier effect eliminates the limitation of the free spectral range on the magnification factor by detecting the intersection response of internal envelopes, and realizes the secondary sensitization of the traditional Vernier effect. Combing the characteristics of HASCF, PDMS, and first-order harmonic Vernier effect, the sensor exhibits a high detection sensitivity of −19.22 nm/°C. The proposed sensor provides not only a design scheme for compact fiber-optic sensors, but also a new strategy to enhance the optical Vernier effect.

A novel high sensitivity all-fiber Fabry-Perot interferometer (FPI) gas refractive index (RI) sensor based on hole-assisted one-core fiber (HAOCF) and Vernier effect was proposed and demonstrated. The sensor is fabricated by splicing a section of HAOCF to a section of silica tube (ST) fused with the lead-in single-mode fiber (SMF), ensuring that the sensor is composed of an air-cavity FPI and a silica-cavity FPI. The cascaded dual-cavities generate the Vernier effect due to a similar free spectrum range (FSR), which significantly improve the sensitivity of the sensor. Owing to the air hole in the cladding of the HAOCF, gases with different RI can enter or leave the in-fiber air cavity, which makes the device usable as a gas RI sensor. The sensor was used to monitor the RI changes of air with different pressures and provided a high sensitivity of -9462.4 nm/RIU. The proposed sensor has a potential to find further applications in the fields of gas composition detection, medical diagnostics and environmental monitoring.

Despite the numerous available treatments for cancer, many patients succumb to side effects and reoccurrence. Zinc oxide (ZnO) quantum dots (QDs) are inexpensive inorganic nanomaterials with potential applications in photodynamic therapy. To verify the photoluminescence of ZnO QDs and determine their inhibitory effect on tumors, we synthesized and characterized ZnO QDs modified with polyvinylpyrrolidone. The photoluminescent properties and reactive oxygen species levels of these ZnO/PVP QDs were also measured. Finally, in vitro and in vivo experiments were performed to test their photodynamic therapeutic effects in SW480 cancer cells and female nude mice. Our results indicate that the ZnO QDs had good photoluminescence and exerted an obvious inhibitory effect on SW480 tumor cells. These findings illustrate the potential applications of ZnO QDs in the fields of photoluminescence and photodynamic therapy.

A bolt-connected deep-sea manned cabin made of maraging steel 18Ni(250) with an inner diameter of 2.1 m is under development, which will be applied to full ocean depth. As a promising guideline, the design formula by CCS is considered to be applied. However, the formula is originally derived based on titanium alloys with a strength level of 800 MPa. Whether it can be used for manned cabin of maraging steel in case of no change in the design coefficients should be checked. A model sphere will be designed and tested to collapse under uniform external pressure inside a high-pressure chamber to check the effectiveness and practicability of the design formula and the manufacture technology. Results of ultimate strength predicted or calculated by the design formula and direct finite element methods are compared with the experimentally obtained value. The influence of simplification on material properties and initial geometry imperfection is considered and discussed.