Tapered fiber coated with hydroxyethyl cellulose/polyvinylidene fluoride composite for relative humidity sensor

A new evanescent wave based sensor is proposed and demonstrated using a silica fiber interferometer coated with Hydroxyethyl Cellulose/Polyvinylidene Fluoride (HEC/PVDF) composite. The performance of the sensor is investigated for two different types of interferometer structure: inline Mach Zehnder Interferometer (MZI) with dumbell structure and non-adiabatic etched fiber. The measurement is based on interferometric technique where the transmission spectrum of the reflected light is investigated for changes in relative humidity. For instance, the resonant dip wavelength for MZI dumbbell shape increases from 1555.76 to 1556.34 nm as the RH increases from 10 to 80. While, for etched SMF the resonant dip wavelength increases from 1554.58 to 1554.85 nm as the RH increases from 10 to 80. Both sensors demonstrated a linear shift especially within a range from 20 to 45. It is found that the MZI-based sensor has a sensitivity of 0.0123 nm/ with a linearity of 99.88 and limit of detection of 0.44. On the other hand, the etched SMF structure also shows change in the resonant wavelength with the increase in RH. The tapered fiber based sensor has a sensitivity of 0.0074 nm/ with linearity of 98.85 and limit of detection of 0.65. The lower limit of detection for dumbbell structure shows that the system is more efficient than etched SMF structure. The proposed sensor has a high potential for RH measurement as it has easy to fabricate, low fabrication cost, and compact size. (C) 2015 Elsevier B.V. All rights reserved

Multi-wavelength fiber laser with erbium doped zirconia fiber and semiconductor optical amplifier

Multi-wavelength hybrid fiber lasers are demonstrated in both ring and linear cavities using a fabricated Erbium-doped Zirconia fiber (EDZF) and semiconductor optical amplifier (SOA) as gain media. In both configurations, the a fiber loop mirror, which is constructed using a 3 m long polarization maintaining fiber (PMF) and a polarization insensitive 3dB coupler is used as a comb filter for the fiber laser. In the ring cavity, 10 simultaneous lines with peak power above -26 dBm is obtained at 1550 nm region. This is an improvement compared to the linear cavity configuration which has only 5 simultaneous lines observed from wavelength 1556.1 nm to 1563.0 nm with the peak power above -40 dBm. Both hybrid lasers has a constant line spacing of 1.7 nm, which is suitable for wavelength division multiplexing and sensing applications and shows a stable operation at room temperature

Control of vehicle driving model by non-linear controller

A new drive control system which has an effect on controlling the vehicle slip during accelerating and braking is proposed in this paper. This drive control system uses a nonlinear controller designed by following the Lyapunov theorem. The controller is designed in order that it can work at both conditions that is the slippery and non-slippery road. The effectiveness of this control system is proved by a basic experiments

Dual-wavelength thulium ytterbium Co-doped fiber laser

We report on the generation of dual-wavelength fiber laser peaking at 1990.64 and 1998.92 nm with a simple ring cavity setup. The lasers are demonstrated using a fabricated silica-based nanoengineered octagonal shaped double-clad Thulium-Ytterbium co-doped fiber (TYDF) as a gain medium in a simple all-fiber ring configuration. By using 980 nm multimode laser, a stable dual-wavelength laser is generated at a threshold pump power of 1500 mW due to the non-polarization rotation (NPR) effect occurred in the cavity. The effect has been self-controlled by a suppression of mode competition in the gain medium. The result shows that the slope efficiency of the generated dual–wavelength laser is measured to be 27.23%. This dual-wavelength TYDF laser operated steadily at room temperature with a 34 dB optical signal-to-noise rati

Local Descriptor for Retinal Fundus Image Registration

A feature-based retinal image registration (RIR) technique aligns multiple fundus images and composed of pre-processing, feature point extraction, feature descriptor, matching and geometrical transformation. Challenges in RIR include difference in scaling, intensity and rotation between images. The scale and intensity differences can be minimised with consistent imaging setup and image enhancement during the pre-processing, respectively. The rotation can be addressed with feature descriptor method that robust to varying rotation. Therefore, a feature descriptor method is proposed based on statistical properties (FiSP) to describe the circular region surrounding the feature point. From the experiments on public Fundus Image Registration dataset, FiSP established 99.227% average correct matches for rotations between 0° and 180°. Then, FiSP is paired with Harris corner, scale-invariant feature transform (SIFT), speeded-up robust feature (SURF), Ghassabi's and D-Saddle feature point extraction methods to assess its registration performance and compare with the existing feature-based RIR techniques, namely generalised dual-bootstrap iterative closet point (GDB-ICP), Harris-partial intensity invariant feature descriptor (PIIFD), Ghassabi's-SIFT, H-M 16, H-M 17 and D-Saddle-histogram of oriented gradients (HOG). The combination of SIFT-FiSP registered 64.179% of the image pairs and significantly outperformed other techniques with mean difference between 25.373 and 60.448% (p = <;0.001*)

Lutetium Oxide Film As A Passive Saturable Absorber For Generating Q-Switched Fiber Laser At 1570 nm Wavelength

We report for the first time, the application of Lutetium oxide (Lu2O3) thin film as a saturable absorber (SA) in generating a stable and compact Q-switched Erbium-doped fiber laser (EDFL) operating at 1570 nm. The film SA was prepared by embedding the Lu2O3 particles into a polyvinyl alcohol (PVA) host film. By integrating the film SA in a laser cavity, a stable pulsed laser appeared when the input pump power hit the threshold at 26.3 mW. The frequency of the pulsed laser rose from 18.4 kHz to 30.4 kHz, matching the increase of pump power from 26.3 mW to 71.6 mW. The shortest pulse width of 8.47 µs and the highest peak power of 8.98 mW were obtained at the maximum available pump power of 71.6 mW. Meanwhile, the maximum output power and pulse energy were measured at approximately 2.32 mW and 76 nJ, respectively. In addition, the signal to noise ratio (SNR) was 40 dB. These indicators suggest that Lutetium oxide film is a good passive SA that can be used to generate pulsed laser operating at1.55 µm region

Vacuum/Compression Valving (VCV) Using Parrafin-Wax on a Centrifugal Microfluidic CD Platform

This paper introduces novel vacuum/compression valves (VCVs) utilizing paraffin wax. A VCV is implemented by sealing the venting channel/hole with wax plugs (for normally-closed valve), or to be sealed by wax (for normally-open valve), and is activated by localized heating on the CD surface. We demonstrate that the VCV provides the advantages of avoiding unnecessary heating of the sample/reagents in the diagnostic process, allowing for vacuum sealing of the CD, and clear separation of the paraffin wax from the sample/reagents in the microfluidic process. As a proof of concept, the microfluidic processes of liquid flow switching and liquid metering is demonstrated with the VCV. Results show that the VCV lowers the required spinning frequency to perform the microfluidic processes with high accuracy and ease of control.open5