Nonlinear optical properties of integrated GeSbS chalcogenide waveguides

In this paper, we report the experimental characterization of highly nonlinear GeSbS chalcogenide glass waveguides. We used a single-beam characterization protocol that accounts for the magnitude and sign of the real and imaginary parts of the third-order nonlinear susceptibility of integrated Ge23Sb7S70 (GeSbS) chalcogenide glass waveguides in the near-infrared wavelength range at λ = 1580 nm. We measured a waveguide nonlinear parameter of 7.0 ± 0.7 W−1 · m−1, which corresponds to a nonlinear refractive index of n2 = (0.93 ± 0.08) × 10−18 m2/W, comparable to that of silicon, but with an 80 times lower two-photon absorption coefficient βTPA= (0.010 ± 0.003) cm/GW, accompanied with linear propagation losses as low as 0.5 dB/cm. The outstanding linear and nonlinear properties of GeSbS, with a measured nonlinear figure of merit FOMTPA= 6.0 ± 1.4 at λ = 1580 nm, ultimately make it one of the most promising integrated platforms for the realization of nonlinear functionalities.