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.