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Suzhou, China

Miao P.-P.,Jiangnan University | Zhu Y.-Q.,Jiangnan University | Wang J.,Jiangnan University | Tao X.-C.,Jiangnan University | And 2 more authors.
Guangzi Xuebao/Acta Photonica Sinica | Year: 2015

Based on the gradient characteristic of taper of optical fiber and the change of degree of fusion between two fibers of fused fiber coupler in the drawing process, the changing model of waveguide structure of optical fiber coupler was constructed. The relationship between optical power and stretching length was obtained, and optical field distribution during drawing process was gotten by numerical simulation with beam propagation method. The simulation and experimental results show that hydrogen flow and drawing speed have an influence on degree of fusion. Large hydrogen flow and low speed make degree of fusion large. The coupling effect between fibers is related to the stretching length and the degree of fusion. Long stretching length and large degree of fusion make coupling effect strong. When the stretched length is short, the coupling of taper region can be ignored. On the one hand, it's revealed fibers become thinner and coupling effect becomes stronger in taper region with the increasing of stretched length. On the other hand it is also showed that the energy leaks out of the fiber and it leads to excess loss. ©, 2015, Chinese Optical Society. All right reserved. Source

Wang L.,Tianjin University | Meng Z.,Tianjin University | Yao X.S.,Tianjin University | Liu T.,Tianjin University | And 2 more authors.
IEEE Photonics Technology Letters | Year: 2012

An adaptive speckle denoising method called Volume-BM3D is developed for optical coherence tomography (OCT) volume data processing, including an adaptive noise level estimation algorithm and a denoising strategy based on block-matching and filtering in a highly sparse local 3-D transform domain. Noise level estimation, an important step for denoising, is obtained from estimating signal fluctuations among neighboring A-Scans. Unlike 2-D denoising approaches, the Volume-BM3D considers the similarities of tissue structures either in a single 2-D image or in a volume data simultaneously. It not only effectively suppresses speckle noise, but also improves the visualization of small morphological features, such as sweat glands in finger images. Application of this proposed method to the OCT volume data of a human finger tip shows an 18.4-dB signal-to-noise ratio improvement in speckle noise reduction with little edge blurring. It outperforms other filtering methods in suppressing speckle noises and revealing attenuated subtle features. © 2012 IEEE. Source

Li Z.,Tianjin University | Li Z.,Suzhou Opto ring Co. | Meng Z.,Tianjin University | Wang L.,Tianjin University | And 4 more authors.
IEEE Photonics Technology Letters | Year: 2015

We report the first study of using optical coherence tomography (OCT) to inspect the winding quality of fiber optical gyro coils. We use a swept-source OCT system to scan a quadrupole-wind fiber coil for obtaining its two-dimensional and three-dimensional (3D) tomographic images. The defects beneath the surface of the fiber coil, which otherwise are invisible by video inspection, can be clearly identified with such tomographic images. The winding quality of each layer can also be independently visualized with the reconstructed 3D images from different angles or in different sections. We believe that the proposed method will be useful to ensuring the quality production of each and every fiber gyro coil. © 2014 IEEE. Source

Su Y.,Tianjin University | Meng Z.,Tianjin University | Meng Z.,Suzhou Opto ring Co. | Wang L.,Tianjin University | And 4 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

The living human skin has complex composition of tissue in several distinctive layers with various thicknesses, and different tissues have different glucose dependence of optical properties. Therefore, the calculation analysis method to find the maximum correlation region containing minimum noise to be used for calibration is worth being concerned in noninvasive blood glucose monitoring. We report an algorithm using correlation analysis to calculate the depth of region, which has the maximum correlation between blood glucose concentration and tissue optical properties. The selected correlation region also has the least noise interference from other skin layers. This method can improve the prediction precision of the noninvasive blood glucose concentration measuring and has a value for application. Source

Su Y.,Hebei University of Science and Technology | Yao X.S.,Hebei University of Science and Technology | Yao X.S.,General Photonics Corporation | Wei C.,Hebei University of Science and Technology | And 3 more authors.
IEEE Photonics Journal | Year: 2016

We use optical coherence tomography (OCT) to systematically study the dependence of the optical attenuation coefficient μt upon the applied pressure P in different depth regions of the human skin in vivo. We find that the same OCT data can be used to estimate thicknesses of the epidermis layer and the epidermis-dermis junction and obtain the thickness changes in these skin layers induced by the pressure. We further propose and demonstrate using the correlation map to identify depth regions in which μt has positive and negative correlations with the applied pressure and study in detail the changes of μt in dermis with the applied pressure. By using a low-cost thin-film pressure sensor to monitor the applied pressure accurately, we are able to quantitatively obtain the pressure dependence of μt in different skin layers in vivo with the following interesting findings: When a pressure ranging from 0 to 20 kPa is applied on the volar side of the forearm skin, μt increases with the applied pressure in the epidermis layer, which coincides with the thickness decrease and increase of the epidermis and the epidermis-dermis junction, respectively. In contrast, μt decreases with applied pressure in the upper dermis but increases again in the deeper dermis with applied pressure. Our results demonstrate that the OCT correlation map and the thin-film sensor are effective tools to study the optical scattering properties of human skin under pressure. We anticipate that our experimental and analytical methods reported in this paper can be useful for clinical diagnostic applications, such as noninvasive blood glucose monitoring. © 2009-2012 IEEE. Source

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