Simulation-assisted design of a compact tunable phase-modulated DBR/ring laser diode

We present a numerical model based on Coupled Mode Theory for modelling and optimization of thermally tuned semiconductor lasers used in digital coherent transceivers. This modular approach allows combinations of waveguides, gratings and microrings, and enables the quick simulation of longitudinal modes. Our comparative study shows that the combination of a phase-modulated DBR and a microring results in a promising, compact tunable laser diode for telecommunication and signal processing. It requires low tuning power due to the small footprint of microring. Wavelength tuning range is controlled effectively by the finite number of peaks of phase-modulated DBR, and the envelope of its reflectivity comb can be optimized numerically.