Numerical investigation of power tunability in two-section QD superluminescent diodes

We present the results of a one-dimensional (1D) numerical model for the simulation of quantum dot (QD) multi-section superluminescent diodes (SLD) using a rate equation approach. A comparison between experimental and simulated P–I characteristics of a single section SLD is provided in order to validate the model parameters. Using these parameters we analyzed more complicated structures with non-uniform injection and waveguide cross section. The purpose has been to investigate how to increase power at the broad-band emission condition (equal power emission from ground state and excited state) and to tune this condition in a wide range of power. We found that applying a non uniform injection in the two sections no improvement in the maximum output power is achieved at the broad bandwidth condition in devices with uniform waveguide. On the contrary, when a tapered section is introduced, the use of two electrodes and non-uniform current injection allows to obtain larger output power and tunability range respect to the case with uniform injection.