Second-harmonic generation using 4-quasi-phasematching in a GaAs whispering-gallery-mode microcavity.

ABSTRACT: The 4 crystal symmetry in materials such as GaAs can enable quasi-phasematching for efficient optical frequency conversion without poling, twinning or other engineered domain inversions. 4 symmetry means that a 90° rotation is equivalent to a crystallographic inversion. Therefore, when light circulates about the 4 axis, as in GaAs whispering-gallery-mode microdisks, it encounters effective domain inversions that can produce quasi-phasematching. Microdisk resonators also offer resonant field enhancement, resulting in highly efficient frequency conversion in micrometre-scale volumes. These devices can be integrated in photonic circuits as compact frequency convertors, sources of radiation or entangled photons. Here we present the first experimental observation of second-harmonic generation in a whispering-gallery-mode microcavity utilizing -quasi-phasematching. We use a tapered fibre to couple into the 5-?m diameter microdisk resonator, resulting in a normalized conversion efficiency ??5 × 10(-5)mW(-1). Simulations indicate that when accounting for fibre-cavity scattering, the normalized conversion efficiency is ??3 × 10(-3)mW(-1).

SUBMITTER: Kuo PS 

PROVIDER: S-EPMC3905730 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature