Optomechanics in GaAs Vertical Pillar DBR Cavities

SEBASTIAN ANGUIANO; AXEL E. BRUCHHAUSEN; ALEJANDRO FAINSTEIN; BERNARD JUSSERAND; PASCALE SENELLART; ARISTIDE LEMAITRE

El Chalten

Conferencia; Discussions on Nano & Mesoscopic Optics (DINAMO-2015); 2015

Resonators that confine light and sound provide a platform to study novel quantum phenomena, including laser cooling and self-oscillation. When such cavity optomechanics is combined with coupled cavity and exciton modes (cavity quantum electrodynamics), new phenomena and devices can be envisaged. Excitonic resonances and cavity polaritons open the way to enormously enhanced optomechanical coupling of photoelastic nature. We propose and study GaAs/AlAs pillar microcavities designed to confine photons and acoustic phonons of the same wavelength, strongly enhancing their interaction. These structures are of great interest because of their very low mechanical effective masses (meff ~ pg), large optomechanical coupling factors (gom ~ THz/nm, go ~ GHz), and ultra-high vibrational frequencies, being accessible optomechanical phenomena of a dynamical nature which require that the decay time of the photons inside the cavity is comparable to or longer than the mechanical oscillator period. Picosecond acoustics and purposely designed ultra-high resolution Raman experiments are used to study the optomechanical vibrational modes in the range between 20-100 GHz, in pillar structures of diameters down to 1 micrometer, and with optical Q-factors ~ 104. Evidence of enhanced vibrational dynamics of pillar structures respect to planar devices is reported for the first time. The prospect of the proposed system for the demonstration of stimulated phonon emission through cavity parametric instability, and for laser cooling down to the quantum ground state, is discussed.