High-Accuracy Measurement of Refractive Indices in GaAs/AlGaAs Thin-Film Heterostructures

Accurate knowledge of the refractive index,$n$, of optical materials is required for the development of many optical devices in the visible (VIS), near- (NIR) and mid-infrared (MIR) spectral regions, such as lasers, light-emitting and super-luminescent diodes, and distributed Bragg reflectors (DBRs). Typically,$n$shows a variability depending on deposition conditions, which motivates the need for routine characterization of as-produced structures. While several measurement methods for$n$exist, among them (spectroscopic) ellipsometry and Fourier-transform infrared (FTIR) refractometry, they all come with their (dis-)advantages, e.g., accurate goniometric measurements or high-resolution FTIR [1].