Linear and Nonlinear Optical Properties of Ge-Sb-Se Waveguides at Telecom Wavelengths

Enhancement of third-order nonlinearity of thermally evaporated GeSbSe waveguides through annealing

“…The average TPA for the 330 nm and 380 nm waveguides was observed to be 0.024 ± 0.009 cm/GW and 0.020 ± 0.01 cm/GW respectively. These values are larger than the previously reported value of 0.014 cm/GW at 1550 nm [1,30], due to the fact that most of the supercontinuum bandwidth occurs above the half bandgap. The TPA coefficient for chalcogenides increases significantly when the photon energy exceeds the half bandgap [18], and we observe the majority of the supercontinuum bandwidth to occur above the half bandgap.…”

“…It is not however expected to significantly impact the nonlinear index. Previous z-scan measurements of glasses with similar stoichiometry showed a slightly lower nonlinear index of 8-10×10 −18 m 2 /W [16,18,24,41,42], compared to 11.3×10 −18 m 2 /W [16], of the bulk Ge 28 Sb 12 Se 60 , but still much larger than the previously measured thin film nonlinear index of 0.5×10 −18 m 2 /W [1]. The Raman spectra from bulk Ge 28 Sb 12 Se 60 and a 330 nm thermally evaporated thin film.…”

“…Thermal evaporation may also result in inclusions of trapped gas and thermal stress [29]. Both this study and previous studies show that the thermally evaporated films and the melt-quench prepared bulk glasses exhibit different optical nonlinearity [1,16].…”

“…Z-scan measurements have demonstrated an n 2 of 11.3×10 −18 m 2 /W in melt-quench prepared bulk Ge 28 Sb 12 Se 60 [16], while the n 2 of thermally evaporated Ge 28 Sb 12 Se 60 waveguides has been measured to be 0.5×10 −18 m 2 /W [1,30]. This decrease in nonlinearity shows that the deposition process has affected the nonlinear optical properties of the chalcogenide.…”

“…A wide variety of nonlinear materials have been studied and used to produce novel devices in the visible and near infrared (NIR), but materials for the mid-(MIR) and far-infrared (FIR) have yet to be fully developed. Chalcogenide glasses are a promising candidate for NIR to FIR applications due to their broadband transmission and high nonlinear properties [1][2][3]. Preliminary demonstrations have shown that the nonlinearity in chalcogenide glasses can be used to create novel sources in the near to far-infrared [4][5][6][7][8][9][10][11].…”