Enhancement of Er luminescence in microdisk resonators made of Er,O-codoped GaAs

We report on the fabrication and optical characteristics of microdisk (MD) resonators with Er,O-codoped GaAs (GaAs:Er,O) as an active component. MD resonators based on GaAs:Er,O with different sidewall angles are fabricated by electron beam lithography followed by two different processes: dry and wet etching. Numerical simulations using a finite-difference time-domain method demonstrate an increase in the cavity quality (Q) factor of the MDs when sharpening the taper angle of the MDs. Micro-photoluminescence characterization of the MD resonators with excitation by a He–Ne laser reveals an 11.4-fold enhancement of Er-related luminescence and a cavity Q factor of 4.2 × 103. For the MD resonators with tapered sidewalls, further enhancement of Er luminescence and increased Q factor (>9.0 × 103) are observed.