Optoelectronic forces with quantum wells for cavity optomechanics in GaAs/AlAs semiconductor microcavities

Abstract

Radiation pressure, electrostriction, and photothermal forces have been investigated to evidence backaction, non-linearities and quantum phenomena in cavity optomechanics. We show here through a detailed study of the relative intensity of the cavity mechanical modes observed when exciting with pulsed lasers close to the GaAs optical gap that optoelectronic forces involving real carrier excitation and deformation potential interaction are the strongest mechanism of light-to-sound transduction in semiconductor GaAs/AlAs distributed Bragg reflector optomechanical resonators. We demonstrate that the ultrafast spatial redistribution of the photoexcited carriers in microcavities with massive GaAs spacers leads to an enhanced coupling to the fundamental 20 GHz vertically polarized mechanical breathing mode. The carrier diffusion along the growth axis of the device can be enhanced by increasing the laser power, or limited by embedding GaAs quantum wells in the cavity spacer, a strategy used here to prove and engineer the optoelectronic forces in phonon generation with real carriers. The wavelength dependence of the observed phenomena provide further proof of the role of optoelectronic forces. The optical forces associated to the different intervening mechanisms and their relevance for dynamical backaction in optomechanics are evaluated using finite-element methods. The results presented open the path to the study of hitherto seldom investigated dynamical backaction in optomechanical solid-state resonators in the presence of optoelectronic forces.

Polariton-driven phonon laser

“…Assuming η = 40% (ref. 36 ), and a value of previously reported for a pillar DBR microcavity 37 , this estimation yields mW. The hybrid polariton BEC optomechanical system already fulfills this conditions for self-oscillations at the BEC condensation threshold ( P Th ~ 19 mW for the 1.6 μm traps).…”

Optical cavity mode dynamics and coherent phonon generation in high- Q micropillar resonators

“…Even though the traces are strongly dominated by the electronic contribution, hidden in them there are faint oscillations induced by the confined acoustic vibrations. These vibrations are generated by the photoexcited carriers through deformation potential interaction [27,28], and can be singled out through Fourier analysis. To further understand the effect of lateral confinement on these vibrations, we selected, for each pillar, the trace corresponding to the specific detuning that leads to the absolute maximum in the amplitude of the measured oscillations.…”

Quantum well photoelastic comb for ultra-high frequency cavity optomechanics

“…17, 28,29 In these Brillouin-Raman processes no real excitation of electron-hole pairs, as in Ref. 27, occurs. We will experimentally show here that this feature can be exploited using highly localized excitonic resonances in quantum wells to define photoelastic combs conceived to strongly, selectively, and efficiently couple through electrostrictive forces confined photon states with specific ultra-high frequency mechanical vibrations of the resonators.…”

“…17,18 In these semiconductor materials photons can exert stress through radiation pressure 19 , electrostriction (linked to the materials photoelasticity) 7,20 , thermal forces 21-23 , and so-called optoelectronic forces based on deformation potential interaction involving real photoexcited carriers. [24][25][26][27] In structures based on GaAs/AlAs materials the introduction of quantum wells (QWs) allows an additional degree of freedom to tailor these optical forces. The idea to use QWs for engineering the dynamics of photoexcited carriers operative in optoelectronic forces evidenced in time-resolved experiments with ultrafast pulsed lasers tuned with the absorption gap was reported in Ref.…”