Continuous-wave operation of an electrically pumped single microribbon based Fabry-Perot microlaser.

Abstract

Fabry-Perot (FP) mode microlasers have been popularized and applied widely in on-chip coherent light sources because of the unique advantages of directional output emission. In this work, a heterojunction light-emitting diode (LED) made of a Ga-doped ZnO (ZnO:Ga) microribbon and p-GaAs template is fabricated. And its electroluminescence characteristics of strong coupling of exciton-photon and polariton lasing, in the blue-violet spectrum, were demonstrated under continuous-wave operation of an electrical injection. In the device structure, a single microribbon with a rectangular-shaped cross section can achieve the FP-mode lasing action by the optical oscillation between the two lateral sides of the microcrystals in the ultraviolet spectrum. As the reverse-current is below the threshold value, the device can have radiative polaritonic lighting directly from bilateral sides of the microribbon, yielding strong coupling between excitons and FP-mode microresonator. And the exciton-polariton coupling strengths characterized by a Rabi splitting energy were extracted to be 500 meV. Further, when the input current increased more than a certain value, strong laser illuminating developed as two sharp peaks at the lower energy shoulder of the spontaneous emission peak, and these oscillating modes can dominate the waveguide EL spectra. The experimental results can provide us with further unambiguous evidence that the lasing is originated from the polariton resonances for the microribbon with strong exciton-polariton coupling. Since single microribbon based optical FP-mode microresonators do not require additional feedback mirrors, their compact size and resulting low thresholds make them a powerful candidate to construct on-chip coherent light sources for future integrated nanophotonic and optoelectronic circuitry.