In this paper we propose an efficient technique for micromachining lithium niobate that is used in Ti-diffused waveguides. The use of Focused Ion Beam (FIB) etching allows obtaining homogeneous periodic microstructures. Bragg gratings with a period of 1.05 m and an aspect ratio of 6:1 (depth-to-half period ratio) have been achieved. A reflectivity greater than 95% associated with a bandwidth at half maximum of about 100 nm within a window centered at 1550 nm, is demonstrated for a Bragg grating of period 3=18 m and a length of 144 m, in good agreement with theoretical predictions.
International audienceThe authors have already presented a novel surface acoustic wave device for vacuum pressure measurement by employing a piezoelectric substrate that has a high value of temperature coefficient of frequency. Frequency-shift measurements as a function of vacuum pressure can be used to extract information about the pressure sensitivity of the device. In this paper, we report that the deposition of an aluminum thin-film layer and rise in the sensor's operating temperature significantly improve the sensitivity of the device. The results are crucial for improving the lower limit of the vacuum pressure measurement, which currently stands around 10-3 Pa
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