A novel quasi-distributed fiber temperature sensor based on the cascaded quantum dot fibers (QDFs) is proposed in this paper. The cascaded QDFs are fabricated by the 3D printing technology and can be divided into two parts QDF1 and QDF2. When the excitation light is coupled into the fiber, the QDF1 emits the 630nm fluorescence and the QDF2 emits the 530nm fluorescence. Because the fluorescence peaks will change with the temperature linearly, it can be used as the fiber temperature sensor. In the experiment, by controlling the temperature at each QDF, the sensor realizes the temperature measurement at different position. The sensitivity of the sensor at different position is 0.15nm/°C and 0.153nm/°C, respectively. The results verify the feasibility of the structure for distributed temperature sensing. The spatial resolution is 1.8mm, which is limited by the length of the printed QDF.
Based on the principle of Solc interferometer, an optical fiber sensor which can realize torsional direction and torsion angle measurement simultaneously is proposed in this paper. The sensor is consisted of a segment of single mode fiber (SMF), polarization maintaining fiber (PMF) and two polarizers. When the light of the broad band source is transmitted in the sensor, the interference spectra can be observed at the output of the sensor. The interference spectra of the sensor can be changed when the sensor is twisted clockwise or counter-clockwise. Because the peaks position and dips position in interference spectra are reversed when clockwise and counter-clockwise torsions are applied, the torsional direction can be judged conveniently. With the increase of the torsion angle, the extinction ratio (ER) of interference spectra will change significantly. By measuring the changes of the ER, torsion angle can be calculated easily. The highest sensitivity can reach to 0.79dB/° in the range of [-50,52°].
A printing method of quantum dots (QDs) optical fiber is presented in this paper. The printing ink with suitable viscosity is composed of the UV adhesive and the CdSe/ZnS quantum dot. By adjusting the pressure and waveform parameters of inkjet printer, a stable droplet is formed. A segment of QDs optical fiber is printed on the organic polymer material substrate subjected to viscous treatment by controlling the spacing between adjacent droplets. When the printed QDs optical fiber is aligned to multi-mode optical fiber which is used to transmit the excitation light, strong fluorescence of the QDs fiber is detected by the optical spectrum analyzer (OSA). Using the printed QDs optical fiber as the senor, the temperature measurement is realized. The sensitivity of the luminescent peak with the temperature is about 115.0pm/°C.
A compact high birefringence polarization maintaining fiber (PMF) sensor for simultaneous strain and temperature measurement is proposed. This sensor is a modal interferometer (MI) sensor which is composed of a segment of high birefringence polarization maintaining fiber. One side of the fiber is spliced to the pigtail of a polarization beam splitter (PBS) with core-offset and axes alignment, the other end is spliced to the standard single-mode fiber (SMF) with core alignment and forms a fiber bubble. In experiments, an optical switch and the PBS are used to generate two orthogonal linear polarized lights. When the two orthogonal linear polarized lights enter the sensing fiber respectively, two different interference spectra will be achieved and own different response to the strain and temperature. Using these properties, the sensor realizes the simultaneous strain and temperature measurement. For 0.01 nm wavelength resolution, the strain and temperature resolution of the sensor are 10 uε and 0.285°C, respectively.
Proc. SPIE. 9685, 8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems; and Smart Structures and Materials
A novel fiber relative humidity (RH) sensor is demonstrated in this paper. The sensor is composed of a fiber Michelson modal interferometer (MMI) and the ZnO nanorods which grown on the fiber to improve the sensitivity of the sensor. Two standard single mode fibers are spliced to form the MMI, misaligned splicing program is used at the spliced point. Relative humidity sensing experiment shows that the intensity of interference spectrum changes linearly with relative humidity. With the relative humidity increasing in the range from 30% to 85%, the intensity of the dip in the interference spectrum linearly increases higher than 50%. The relative humidity response of the sensor is induced by the interference between core mode and cladding mode. The ZnO nanorods with high surface to volume ratio grown outside of the fiber cladding enhance the sensitivity of the sensor.