Direct measurements of large near-band edge nonlinear index change from 1.48 to 1.55 μm in InGaAs/InAlGaAs multiquantum wells

Direct picosecond measurements of nonlinear refractive index change and nonlinear absorption in In0.530Al0.141Ga0.329As/In0.530Ga0.470As multiquantum wells in the range 1480–1550 nm are reported. Large low-threshold nonlinear index changes are found: Δn of up to 0.14 with figure of merit of 1.38 at a fluence of 116 μJ/cm2. The index-change-over-absorption figure of merit, F, is greater than unity over much of the spectrum, pointing to the prospective applicability of the materials studied to nonlinear switching devices.