Claude Chartier

A micropillar for cavity optomechanics

We have designed a micromechanical resonator suitable for cavity optomechanics. We have used a micropillar geometry to obtain a high-frequency mechanical resonance with a low effective mass and a very high quality factor. We have coated a 60-μm diameter low-loss dielectric mirror on top of the pillar and are planning to use this micromirror as part of a high-finesse Fabry-Perot cavity to laser cool the resonator down to its quantum ground state and to monitor its quantum position fluctuations by quantum-limited optical interferometry.

Free-space cavity optomechanics in a cryogenic environment

We present a free-space optomechanical system operating in the 1-K range. The device is made of a high mechanical quality factor micropillar with a high-reflectivity optical coating atop, combined with an ultra-small radius-of-curvature coupling mirror to form a high-finesse Fabry-Perot cavity embedded in a dilution refrigerator. The cavity environment as well as the cryostat have been designed to ensure low vibrations and to preserve micron-level alignment from room temperature down to 100 mK.

An integrated resonator-based thermal compensation for Vibrating Beam Accelerometers

Although the Vibrating Beam Accelerometer (VBA) shows excellent performances (resolution <; 1 μg), its bias drift over temperature and temperature gradient is a main performance limitation. Numerical compensation can be performed with a temperature sensor in the accelerometer package, but this approach shows two drawbacks for fast measurements: first, there is a time delay between the temperature of the vibrating beam and the temperature of the package, and second the noise level is very high. In order to overcome these limitations, a new structure comprising a second resonator in torsional mode placed in the middle of the vibrating beam was designed. It shows good sensitivity and linearity over temperature and senses the instantaneous temperature of the vibrating beam with low noise, allowing a better compensation of thermal drifts. A new accelerometer with resonator-based thermal compensation was designed, realized and tested. Experimental results confirm the excellence of the torsional mode resonator used as a temperature sensor.