The edge-triggered generation of baseband ultra-wideband (UWB)
monocycle pulse using a dual-parallel Mach-Zehnder modulator is
proposed and experimentally demonstrated. By setting three biases of
the modulator at maximum, minimum and linear transmission points
respectively, a monocycle UWB pulse sequence with the fractional
bandwidth of ~ 155% is generated. The pulse sequence is
differential encoded and the pulse bandwidth is determined by the
transition time of the drive edge due to the nonlinear biases of the
modulator. Furthermore, by using a basic digital signal processing
(DSP) algorithm to calculate the bit error rate (BER), the
transmission performance over a 25km-fiber is studied.
A 2×2 and a 1×4 fiber-type optical phased array with PZT phase shifters have been implemented. Fibers are adopted as
transmission paths and emitting antennas in the optical phased array system. By using the feedback optimization we had
proposed before, the inaccuracy of fiber length is overcome. By adjusting the phase shift of each PZT phase shifter
repeatedly according to the algorithm we had proposed for optimization, 1-D and 2-D beam forming and beam steering
in a short period of time have been observed respectively. Moreover, a 1×6 fiber array is also tried. Although the
interference is not stable enough, much narrower beams are achieved.
Vacuum packaging is very important for some micro-electro-mechanical systems (MEMS) devices to perform their basic functions properly and to enhance their reliability by keeping these devices away from harmful external environment. In order to maintain high vacuum in a cavity of MEMS devices, residual gases and leaking gases must be eliminated by getter materials embedded. This paper will report the fabrication and characterization of advanced getter, or micro/nano getters for MEMS applications.
High-temperature and high-pressure connection between micro combustor and macro world for feeding of air/fuel gas is required in PowerMEMS development. A Kovar tubing-Glass-Si sealing process has been developed for an on-going PowerMEMS project to connect Kovar tubes with diameters of 2mm and 4mm, to top Si wafer of micro combustor fabricated by DRIE process. Due to the different CTEs (coefficients of thermal expansion) of the connected materials, thermal stress around the sealing area could probably influence the obturation and other properties of the sealed combustor. A numeric simulation on sealing of the structure was conducted on ANSYS software to investigate this kind of sealing process. The thermal stress and displacement from room temperature to combustion circumstance and to sealing condition as high as 1220K were simulated. The size affection of glass bonder and the metal tubes was investigated. A process of high temperature sealing Kovar-glass-silicon was developed and a prototype of the packaged micro combustor was manufactured.
High-temperature and high-pressure connection between micro combustor and macro world for feeding of air/fuel gas is required in PowerMEMS development. A Kovar tubing-Glass-Si sealing process has been developed for an on-going PowerMEMS project to connect Kovar tubes with diameters of 2mm and 4mm, to top Si wafer of micro combustor fabricated by DRIE process. Due to the different CTEs (coefficients of thermal expansion) of the connected materials, thermal stress around the sealing area could probably influence the obturation and other properties of the sealed combustor. A numeric simulation on sealing of the structure was conducted on ANSYS software to investigate this kind of sealing process. The thermal stress and displacement from room temperature to combustion circumstance, and to sealing condition as high as 1220K were simulated. The size affection of glass bonder and the metal tubes was investigated. A process of high temperature sealing Kovar-glass-silicon was developed and a prototype of the packaged micro combustor was manufactured.
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