Optical modes in pyramidal GaAs microcavities

Abstract

Pyramidal GaAs structures on top of GaAs∕AlAs distributed Bragg reflectors are investigated as candidates for true three-dimensional cavities with potentially low mode volume and high quality-factor. Different types of single and coupled resonators with base lengths of a few microns are realized using a combination of molecular-beam epitaxy, electron-beam lithography, and wet chemical etching. Embedded InGaAs quantum dots are utilized as light sources to verify the resonator modes. Furthermore, a spatially localized emission through the pyramid facets indicates the future possibility of coupling cavity modes to optical fibers. This could be interesting within the context of single photon emitters.

Optical microcavities fabricated by DBR overgrowth of pyramidal-shaped GaAs mesas

“…In the m-PL spectra of various mesas, several sharp peaks were identified as optical modes through the thermal shift of their resonance wavelength [12]. It was also observed that generally a fundamental mode with the lowest photon energy is followed by resonances with higher energies.…”

“…In addition, one should take into account, that the stop band position of a Bragg mirror strongly depends on the incident angle of incoming light. For these reasons, we decided to establish a fabrication process that ends up in the overgrowth of truncated pyramids with gently sloped facets [12,13].…”

“…3, the initial rough exposing of the f1 1 4g A planes on the sidewalls of the mesas was performed by a wet-chemical etching process (Fig. 2b), that allows to adjust the angle between the substrate and the sidewalls from 251 to 651 by varying the hydrogen peroxide content of an 1:x:8 H 3 PO 4 :H 2 O 2 :H 2 O etching solution [12,14]. This variation of the ingredients changes the etching rates in the AlAs sacrificial layer and the GaAs as well as their ratio, leading to a more or less pronounced undercut on the level of the sacrificial layer.…”

Pyramidal assemblies of colloidal particles by micromolding underneath top-gathering pillar arrays

“…Optical cavities with pyramidal shape have been demonstrated to be promising candidates because of internal reflection inside of pyramids [22][23][24][25][26]. The pyramidal assemblies of particles are expected to show the special optical properties due to the scattering, interference and reflection of the light.…”

Templated growth of diamond optical resonators via plasma-enhanced chemical vapor deposition

“…19 GaAs and GaN pyramids have also been used for dielectric 20 and plasmonic 21 cavities, respectively, using the appropriate fabrication techniques for each material system. We performed 3D finite-difference time-domain (FDTD) simulations (Lumerical Solutions) of square pyramid structures (Fig.…”