Thermo-optically tunable Bragg soliton-effect compression in on-chip silicon nitride gratings

In this work, we demonstrate thermo-optic tuning of Bragg soliton-effect temporal pulse compression in an on-chip 4.6 cm-long concatenated silicon nitride apodized Bragg grating, achieving a compression factor of up to 2.2× and continuously tunable output pulse widths ranging from 2.8ps to 4.5ps. The device leverages the strong interplay between dispersion and nonlinearity near the grating stopband, where soliton dynamics enable efficient compression of optical pulses. Thermo-optic tunability is realized through temperature-induced stopband shifts, providing a flexible and continuous method to control the compression process without modifying the device structure. Both numerical simulations and experimental measurements are performed for different soliton numbers, showing good agreement. For an input pulse width of 5 ps, continuously tunable output pulse widths ranging from 2.8ps to 4.5ps are achieved. This approach offers a compact, integrable, and dynamically reconfigurable solution for pulse compression, with potential applications in on-chip nonlinear signal processing, optical communications, and ultrafast photonic systems.