(a) Trampoline and (b) phononic crystal based nanomembranes. (c) Amplitude and phase of the fundamental mode of a trampoline membrane detected with Self-Mixing interferometry. Reducing the atmospheric pressure increases the mechanical resonance quality factor.

Silicon nitride over silicon is an ideal material for mechanical devices. The strong tensile stress allows the realization of large footprint devices with extreme aspect ratios, comparable or exceeding most single-domain 2D materials. The simplest mechanical device, a suspended membrane, is routinely used for advanced optomechanical experiments, including systems governed by quadratic optomechanical coupling in "membrane-in-the-middle" configuration. Our research exploits the mechanical membrane for tuning and control of laser emitters via the external optical feedback (Self-Mixing interferometry), where we demonstrated interesting effects both in the near-infrared [1] and in the THz range [2]. The high sensitivity of this interferometric technique to the mechanical motion can be exploited to realize simple table-top detectors. By exploiting the narrow mechanical linewidth of the resonant modes in vacuum together with the large temperature sensitivity, we demonstrated their use as optomechanical bolometers, working at room temperature in a giant spectral range, from visible to the sub-THz frequencies ( ATTRACT GRANT project). More complex mechanical designs in silicon nitride, like ones based on "dissipation dilution" [3], offer even better performances and could be used for a further increase of the device capabilities.

[1] L. Baldacci, A. Pitanti, L. Masini, A. Arcangeli, F. Colangelo, D. Navarro-Urrios and A. Tredicucci Thermal noise and optomechanical features in the emission of a membrane-coupled compound cavity laser diode , Sci. Rep. (2016)

[2] A. Ottomaniello, J. Keeley, P. Rubino, L. Li, M. Cecchini, E. H. Linfield, A. Giles Davies, P. Dean, A. Pitanti and A. Tredicucci Optomechanical response with nanometer resolution in the self-mixing signal of a terahertz quantum cascade laser , Opt. Lett. (2019)

[3] Y. Tsaturyan, A. Barg, E. S. Polzik and A. Schliesser Ultracoherent nanomechanical resonators via soft clamping and dissipation dilution , Nature Nanotech. 12, 776 (2017)


[GRANT project]


  • Marco Lazzarino, CNR-IOM, Trieste