BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Dirty and Messy Cavity-Optomechanics: a cavity optomechanical plat form for GHz phonon amplification via Anderson-localized optical modes - P edro David Garcia (Consejo Superior de Investigaciones Cientificas) DTSTART:20230523T084500Z DTEND:20230523T093000Z UID:TALK198856@talks.cam.ac.uk DESCRIPTION:We explore [1] Anderson-localized cavity-Optomechanics in a tw o-dimensional optomechanical platform: a waveguide etched in a suspended s ilicon membrane that incorporates a slotted line air defect. Inherent and unavoidable fabrication imperfections are adequate to induce sufficient ba ckscattering to realize Anderson-localization of optical modes. The introd uction of an air slot allows for a strong confinement of the electromagnet ic field that is guided along the slot\, and enhances the ability for ligh t to couple to in-plane mechanical motion. The resulting tightly confined Anderson-localized modes can be driven to enable mechanical amplification and self-sustained phonon lasing via optomechanical back-action. We design the photonic and phononic band structures [2\,3] to realize mechanical la sing up to 6.8 GHz that results from confinement of the mechanical mode. W e confirm the existence of this mode through a combination of cavity optom echanical techniques and Brillouin light scattering spectroscopy. The role of disorder in cavity-Optomechanics has thus far been largely overlooked but our results show that disorder plays a crucial role\, which in part ca n have a decisive impact on device functionality and in part opens perspec tives for studies of multiple scattering and Anderson localization of boso nic excitations with parametric coupling to mechanical degrees of freedom. \n \;\nFigure 1. (a) Micrograph (top view) of an optomechanical nanost ructure. Detail of the roughness due to the fabrication process which lead s to the localization of the electromagnetic field within the air gap. (b) Coherent amplification of a vibrational mode of the structure by dynamica l backaction: the linewidth of a mechanical mode with a frequency around 2 40 MHz (top panel) is narrowed down by red-detuning an external driving la ser to an Anderson-localized optical mode. This dynamical backaction leads to a coherent amplification of the vibrational mode or phonon lasing (low er panel). \;\n \;\nReferences\n[1] G. Arregui\, R. Cecil Ng\, M. Albrechtsen\, S. Stobbe\, C. M. Sotomayor Torres\, P. David Garcí\;a .\nCavity optomechanics with Anderson-localized optical modes.\nPreprint a t https://arxiv.org/abs/2110.11005 (accepted in Physical Review Letters) 2 023.\n[2] O. Florez\, G. Arregui\, M. Albrechtsen\, R. C. Ng\, J. Gomis-Br esco\, S. Stobbe\, C. M. Sotomayor-Torres\, P. David Garcí\;a. Engin eering nanoscale hypersonic phonon transport.\nNature Nanotechnology\, 202 2\, 17\, 947.\n[3] G. Madiot\, R. C Ng\, G. Arregui\, O. Florez\, M. Albre chtsen\, S. Stobbe\, P. D Garcia\, C. M Sotomayor-Torres. Optomechanical g eneration of coherent GHz vibrations in a phononic waveguide.\nPreprint at https://arxiv.org/abs/2206.06913\, 2022. LOCATION:Seminar Room 1\, Newton Institute END:VEVENT END:VCALENDAR