Post-fabrication tuning of circular Bragg grating resonators via atomic layer deposition

Circular Bragg grating resonators have gained a lot of attention in various material platforms due to their high Purcell factors over large bandwidth. Although the bandwidth is on the order of several nanometers, the best performance is given when perfectly matching the resonator's frequency with the frequency of the embedded emitter. The device resonance spectrum depends on many parameters, such that fabrication often renders devices with detuning to the intended frequency. Here, we show a method to tune the resonator mode in post-fabrication via atomic layer deposition. Atomic layer deposition of a dielectric layer (Al2O3) is used to red-shift the optical resonance. While the presented technique is universal for circular Bragg grating resonators within a wide class of material systems, we choose the quaternary semiconductor In0.53Al0.23Ga0.24As and incorporate InAs quantum dots as active material to validate the technique. We show a tuning of the resonator mode of up to (11.3±0.1) nm with (36±1) nm of Al2O3 at about 1460 nm emission wavelength, which is more than half of the experimental linewidth of the mode itself.