Microdisk lasers based on InGaAs/GaAs quantum dots monolithically integrated with a waveguide

Microdisk lasers with diameters of 30 and 40 $\mu$m with an active region based on InGaAs/GaAs quantum dots, laterally coupled to an optical waveguide, were studied. The microlasers and waveguides were fabricated in a single process on a single GaAs substrate. The spectral characteristics at elevated injection currents on the microlaser and/or waveguide exceeding the lasing threshold by up to 4 times were investigated. The possibility of reducing absorption losses in the waveguide by applying a direct bias to it was shown. An optocouple in which a microdisk laser coupled to a waveguide serves as a radiation source and a waveguide photodetector as a radiation receiver was realized. The dark current density of the waveguide photodetector was 1.1 $\mu$A/cm$^2$ at a reverse bias of -6 V.