Optimization of Bragg soliton dynamics for enhanced supercontinuum generation in ultra-silicon-rich-nitride devices [Invited]

Bragg-soliton dynamics in a 2-stage ultra-silicon-rich-nitr ide (USRN) chip-based device, consisting of a cladding-apodized modulated Bragg grating (CMBG) stage and a USRN channel waveguide stage, is studied and optimized for enhanced supercontinuum generation. We observe that the enhancement is strongly dependent on the Bragg-soliton effect temporal compression developing in the CMBG stage, which is linked to both device and input pulse parameters. With the optimal parameter combination, a supercontinuum spanning 610 nm at the -30 dB level is experimentally demonstrated in the 2-stage USRN device, representing a 5x enhancement compared to that in a reference waveguide. Good agreement is obtained between the experimentally measured supercontinuum and simulations based on the generalized nonlinear Schrodinger equation and is consistent with design rules based on Bragg soliton compression. This device provides an encouraging path to generate supercontinuum in compact chip-based platforms, which does not need ultrashort, femtosecond scale pulses, greatly relaxing the pulse width and pulse power requirement.(c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement