Phase-change material-based external cavity lasers for optical communications

We propose an external-cavity laser architecture that employs an external silicon nitride (Si₃N₄) waveguide sidewall Bragg grating integrated with a phase-change material, specifically antimony trisulfide (Sb₂S₃). Leveraging the significant contrast in the effective refractive index between the amorphous and crystalline states of Sb₂S₃, along with its non-volatile phase transition property, this design enables stable, selective lasing at target wavelengths across a broad frequency tuning range. Simulation results indicate that the wavelength tuning range of this structure can cover the entire C-band, with a channel spacing of ∼0.8 nm between adjacent wavelengths. This external-cavity laser offers an efficient solution for optical communications, exhibiting strong potential for enhancing precise wavelength tuning capability, network flexibility, and resource utilization efficiency.