Dual-wavelength generation and tuning by controlling the apodized grating depth in microring resonators

Abstract: Here we show a photonic design for tunable dual-wavelength generation deploying optical nonlinear mode coupling of two coupled III-V semiconductor microring resonators (MRRs) connected to a pump and drop waveguide buses. Here one of the two rings contains a grating, while the other has a planar surface. The underling mechanism for the dual wavelength generation originates from the resonance-detuning of the spectra resulting in non-linear mode mixing. Tunability of the wavelengths is achieved by altering the grating depth of the MRR and the power coupling coefficients. For the grating design of the MRR we select a trapezoidal-profiled apodized grating to gain low reflectivity at sidelobes. A time-domain travelling wave (TDTW) analysis gives a InGaAsP core refractive index of 3.3 surrounded by a grating InP cladding with n=3.2. We further confirm that the propagation of a Gaussian pulse input with 10 mW power and bandwidth of 0.76 ps is well confined within the mode propagation of the system. Taken together our results show a 2:1 fan-out of two spectrally separate signals for compact and high functional sources on chip.