scholarly journals Strain-Independent Temperature Measurements with Surface-Glued Polarization-Maintaining Fiber Bragg Grating Sensor Elements

Sensors ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 144 ◽  
Author(s):  
Barbara Hopf ◽  
Bennet Fischer ◽  
Thomas Bosselmann ◽  
Alexander W. Koch ◽  
Johannes Roths
Keyword(s):  
Measurement Range ◽  
Temperature Measurements ◽  
Temperature Dependent ◽  
Sensor Element ◽  
Space Applications ◽  
Optical Axes ◽  
Polarization Maintaining Fiber ◽  
Polarization Maintaining ◽  
Bragg Grating Sensor ◽  
First Time

A novel technique for strain and temperature decoupling with surface-glued fiber Bragg gratings (FBGs) is presented and applied for strain-independent temperature measurements in a temperature range between −30 °C and 110 °C with uncertainties below 4 °C over the entire measurement range. The influence of temperature-dependent glue-induced transversal forces on the fiber sensor could be eliminated with a sensor element consisting of two FBGs in identical polarization-maintaining fibers that were spliced perpendicular to each other. After aligning and gluing the sensor element with its optical axes parallel and perpendicular to the specimen, the averaged Bragg wavelength shifts of both FBGs were proven to be independent of the glue’s influence and therefore independent of any change in the material characteristics of the glue, such as aging or creeping behavior. For the first time, this methodology enables temperature measurements with surface-attached bare FBGs independently of arbitrary longitudinal and glue-induced strains. This is of great value for all applications that rely on a fully glued sensor design, e.g., in applications with high electromagnetic fields, on rotating parts, or in vacuum for space applications.

VLSI for Space Applications—Single Event Effect Investigation and Optical Analysis on an Integrated Laser Platform

2017 ◽  
Author(s):  
Samuel Chef ◽  
Chung Tah Chua ◽  
Yu Wen Siah ◽  
Philippe Perdu ◽  
Chee Lip Gan ◽  
...  
Keyword(s):  
Pulsed Laser ◽  
Single Event ◽  
Optical Analysis ◽  
Space Applications ◽  
Laser Probing ◽  
Single Event Effect ◽  
Evaluation Time ◽  
Black Boxes ◽  
System Use ◽  
First Time

Abstract Today’s VLSI devices are neither designed nor manufactured for space applications in which single event effects (SEE) issues are common. In addition, very little information about the internal schematic and usually nothing about the layout or netlist is available. Thus, they are practically black boxes for satellite manufacturers. On the other hand, such devices are crucial in driving the performance of spacecraft, especially smaller satellites. The only way to efficiently manage SEE in VLSI devices is to localize sensitive areas of the die, analyze the regions of interest, study potential mitigation techniques, and evaluate their efficiency. For the first time, all these activities can be performed using the same tool with a single test setup that enables a very efficient iterative process that reduce the evaluation time from months to days. In this paper, we will present the integration of a pulsed laser for SEE study into a laser probing, laser stimulation, and emission microscope system. Use of this system will be demonstrated on a commercial 8 bit microcontroller.

scholarly journals Group-Birefringence-Dispersion Measurements for Polarization-Maintaining Fibers Using a Kerr Phase-Interrogator

2020 ◽  
Vol 10 (24) ◽  
pp. 9031
Author(s):  
Yang Lu
Keyword(s):  
Group Delay ◽  
Laser Wavelength ◽  
Differential Group Delay ◽  
Optical Signals ◽  
Differential Group ◽  
Principal Axes ◽  
Polarization Maintaining Fiber ◽  
Elliptical Core ◽  
Polarization Maintaining ◽  
The Impact

A method which utilizes a Kerr phase-interrogator to measure the group birefringence dispersion (GBD) of a polarization-maintaining fiber (PMF) is systematically studied in this paper. The differential group delay of two sinusoidally modulated optical signals (SMOSs) polarized along the principal axes of the PMF is measured by a Kerr phase-interrogator, which leads to the group birefringence of the PMF. As the laser wavelength of the SMOSs varies, the group birefringence as a function of the laser wavelength is obtained, and the GBD is calculated as the derivative of the group birefringence with respect to the laser wavelength. The proposed method is experimentally demonstrated by characterizations of a Panda PMF with high GBD and an elliptical core PMF with low GBD, and its performance is analyzed. The proposed method eliminates the impact of the laser coherent length and allows for characterizing the GBD of PMFs that are tens of kilometers long.

scholarly journals Temperature-Dependent Photoluminescence of ZnO Thin Films Grown on Off-Axis SiC Substrates by APMOCVD

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1035
Author(s):  
Ivan Shtepliuk ◽  
Volodymyr Khranovskyy ◽  
Arsenii Ievtushenko ◽  
Rositsa Yakimova
Keyword(s):  
Optical Properties ◽  
Structural Quality ◽  
Organic Chemical ◽  
Zno Films ◽  
Vicinal Surfaces ◽  
Temperature Dependent ◽  
Step Flow ◽  
Step Flow Growth ◽  
First Time ◽  
Temperature Dependent Photoluminescence

The growth of high-quality ZnO layers with optical properties congruent to those of bulk ZnO is still a great challenge. Here, for the first time, we systematically study the morphology and optical properties of ZnO layers grown on SiC substrates with off-cut angles ranging from 0° to 8° by using the atmospheric pressure meta–organic chemical vapor deposition (APMOCVD) technique. Morphology analysis revealed that the formation of the ZnO films on vicinal surfaces with small off-axis angles (1.4°–3.5°) follows the mixed growth mode: from one side, ZnO nucleation still occurs on wide (0001) terraces, but from another side, step-flow growth becomes more apparent with the off-cut angle increasing. We show for the first time that the off-cut angle of 8° provides conditions for step-flow growth of ZnO, resulting in highly improved growth morphology, respectively structural quality. Temperature-dependent photoluminescence (PL) measurements showed a strong dependence of the excitonic emission on the off-cut angle. The dependences of peak parameters for bound exciton and free exciton emissions on temperature were analyzed. The present results provide a correlation between the structural and optical properties of ZnO on vicinal surfaces and can be utilized for controllable ZnO heteroepitaxy on SiC toward device-quality ZnO epitaxial layers with potential applications in nano-optoelectronics.

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