2016/02/26 by Baldacci, Lorenzo, Pitanti, Alessandro, Masini, Luca +4
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Optics (physics.optics)
paper · doi:10.48550/arxiv.1602.08453
We demonstrate the use of a compound optical cavity as linear displacement detector, by measuring the thermal motion of a silicon nitride suspended membrane acting as the external mirror of a near-infrared Littrow laser diode. Fluctuations in the laser optical power induced by the membrane vibrations are collected by a photodiode integrated within the laser, and then measured with a spectrum analyzer. The dynamics of the membrane driven by a piezoelectric actuator is investigated as a function of air pressure and actuator displacement in a homodyne configuration. The high Q-factor (∼ 3.4⋅ 104 at 8.3 ⋅ 10-3 mbar) of the fundamental mechanical mode at ∼ 73 kHz guarantees a detection sensitivity high enough for direct measurement of thermal motion at room temperature (∼ 87 pm RMS). The compound cavity system here introduced can be employed as a table-top, cost-effective linear displacement detector for cavity optomechanics. Furthermore, thanks to the strong optical nonlinearities of the laser compound cavity, these systems open new perspectives in the study of non-Markovian quantum properties at the mesoscale.