Stimulated Brillouin Scattering in Low-Loss Ge25Sb10S65 Chalcogenide Waveguides

In this work, we report experimental characterizations of stimulated Brillouin scattering (SBS) in low-loss Ge ₂₅ Sb ₁₀ S ₆₅ (GeSbS) chalcogenide waveguides. A 7-cm-long spiral waveguide with a propagation loss as low as 0.2 dB/cm and a microring resonator with a high loaded quality factor of 1.34×10 ⁶ are demonstrated. In addition, we use a high-resolution pump-probe measurement technique to investigate the SBS characteristics in the GeSbS waveguide. The measured Brillouin frequency shift and the intrinsic Brillouin linewidth are 7.443 GHz and 47.8 MHz, respectively. A Brillouin-gain coefficient of 338 m ^-1 W ^-1 is obtained, which corresponds to an intrinsic Brillouin gain of 0.524×10 ^-9 m/W, comparable to that of As ₂ S ₃ chalcogenide. Moreover, a 17.6-dB probe gain is achieved with a continuous-wave pump of 200 mW, while nonlinear losses are not observed. The large Brillouin gain, together with the low linear propagation loss and the negligible nonlinear loss, make the GeSbS chalcogenide waveguides become a very promising arsenic-free integrated platform for on-chip Brillouin applications.