Design of Electrically Pumped Nanolaser with Metal–dielectric-Metal Coaxial Ring Cavity

We employ self-consistently coupled opto-electrical simulations to explore the design strategy for a proposed electrically pumped metallic coaxial ring cavity nanolaser. With the optical cavity optimized to the physical size of 1.4(λ/n)3, the lasing ability using two gain medium schemes, bulk InGaAs and InGaAs/InP multiple quantum wells (MQWs), are compared. It is shown that the device with the bulk gain medium lases at 1568 nm, while the gain fails to overcome the optical loss in the case of the MQW gain medium due to its lower modal confinement ratio. Variations in material parameters like carrier mobility and Auger coefficient in the bulk laser or carrier capture time in the MQW laser are found to hardly change the lasing ability, although they do impact lasing threshold and efficiency in the bulk case. To study the possibility of further device down-scaling, the lasing feasibility of a smaller cavity with a size of 0.23(λ/n)3 is investigated. We demonstrate that neither including the Purcell effect nor using a metallic substrate for better mode confinement improves the lasing behavior.