KEYWORDS: Fiber Bragg gratings, Sensors, Waveguides, Demultiplexers, Temperature metrology, Optical design, Channel projecting optics, Data processing, Signal detection, Temperature sensors
A Fiber Bragg Grating (FBG) sensor interrogation system using Arrayed Waveguide Gratings(AWGs) demultiplexer
is designed and studied theoretically and experimentally. By using a temperature tunable arrayed waveguide grating
(AWG), the center wavelength of the FBG sensor is successfully interrogated, with the linear temperature dependence
of the AWG transmission wavelengths. Initial results show that the proposed wavelenght interrogation technology using
AWG demultiplexer could potentially offers a low-cost, compact, and high-performance solution for the interrogation of
FBG distributed sensors and multisensor arrays.
Finite-Difference Beam Propagation Method (FD-BPM) in conventional is modified, according to more accurate
Helmholtz equation, a new arithmetic is advanced. By using the new arithmetic and the old arithmetic in calculating slab
waveguide and calculate the parameter which scales the precision of the method and the calculating time, we prove that
the accuracy of the new arithmetic is improved without affecting time performance. At last we calculate the transmission
mode in the AWG by the new method to show the practical value of the modified arithmetic.
A tunable Fourier domain mode-locked (FDML) laser is designed and realized with Semiconductor Optical Amplifier
(SOA), and laser with wide tunable range and high stability could be acquired. Applying the tunable laser to fiber grating
sensor system could improve Signal Noise Ratio and demodulation precision, enhance the ability of multiplexing and
advance the system performance.
A novel arrayed-waveguide grating (AWG) based on unbent waveguides is proposed. Two graded-index planar waveguides (GISLAB) are used as input and output planar waveguides, respectively, and the arrayed waveguides are replaced by unbent waveguides, which are photosensitive waveguides exposed to UV light twice. Next, the 2-D semivectorial beam propagation method is adopted to simulate the light transmitting process in the device, and the simulation shows that this device and the design are feasible.
X-ray phase contrast imaging is a promising new technology today, but the requirements of a digital detector with large
area, high spatial resolution and high sensitivity bring forward a large challenge to researchers. This paper is related to
the design and theoretical investigation of an x-ray direct conversion digital detector based on mercuric iodide
photoconductive layer with the latent charge image readout by photoinduced discharge (PID). Mercuric iodide has been
verified having a good imaging performance (high sensitivity, low dark current, low voltage operation and good lag
characteristics) compared with the other competitive materials (α-Se,PbI2,CdTe,CdZnTe) and can be easily deposited on
large substrates in the manner of polycrystalline. By use of line scanning laser beam and parallel multi-electrode readout
make the system have high spatial resolution and fast readout speed suitable for instant general radiography and even
rapid sequence radiography.
A novel arrayed-waveguides grating (AWG) used for demultiplexer is proposed. Two graded index planar waveguides (GRIPW) were used for input and output planar waveguide respectively, and the arrayed waveguides were replaced by unbent waveguides that were directly fabricated through UV Written. Theoretical analysis and numerical simulation showed that this device and the design were feasible. The design of the device was also optimized.
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