The nonlinear optical properties of AlGaAs at the half band gap

New CMOS-compatible platforms based on silicon nitride and Hydex for nonlinear optics

“…Historically, two important platforms have been chalcogenide glasses (ChG) [50] and AlGaAs [51]. Chalcogenide glasses have achieved very high performance as nonlinear devices, but realising nanowires with ultrahigh nonlinearity (> 10,000 W -1 km -1 ) has proven elusive due to fabrication challenges, as has also been the goal of achieving a material reliability comparable to that of semiconductors.…”

“…Chalcogenide glasses have achieved very high performance as nonlinear devices, but realising nanowires with ultrahigh nonlinearity (> 10,000 W -1 km -1 ) has proven elusive due to fabrication challenges, as has also been the goal of achieving a material reliability comparable to that of semiconductors. AlGaAs was the first platform proposed for nonlinear optics in the telecom band [51] and offers the powerful ability to tune the nonlinearity and FOM by varying the alloy composition. A significant issue for AlGaAs, however, is that nanowires require challenging fabrication [52] methodsparticularly etching -in order to realize very high, narrow mesa structures.…”

Giant anomalous self-steepening in photonic crystal waveguides

“…In addition to a broad tuning range, these systems are characterized by the ability to separate the contributions of the material constituents from the device geometry. This is in contrast to early approaches in both glass [1] and semiconductors [2] which required a change in material composition to modify the waveguide properties. The role of geometry drastically changed with the advent of microstructured fibers and the demonstration that fabrication parameters could be the dominant contribution to the dispersion [3].…”

“…A more recent numerical investigation showed the wavelength dependence of the nonlinear Kerr effect in silicon channel waveguides leads to values up to tens of femtoseconds near the mode cutoff [20]. An alternative approach for generating SS using cascaded χ (2) media as an effective tunable χ (3) was shown with similar strength as traditional media [21]. To date, self-steepening in tunable χ (3) media has not been explicitly experimentally demonstrated.…”

“…In contrast, material slow light from atomic resonances does not exhibit this enhancement [10]. In PhCWGs we write the effective nonlinear Kerr parameter as γ eff = γ ( n g n o ) 2 = ω c n 2 A eff ( n g n o ) 2 , with the bulk Kerr coefficient n 2 , modal area A eff , and linear refractive index n o . While the γ term is well described in the literature, research into the slow-light enhancement contribution n g n o in 2D PhCWGs required significant advances in nanofabrication techniques which were only mastered the past few years.…”