Revisiting the Fabry–Perot reflectivity method for mid-infrared optical index measurement: case study of InGaAs, AlInAs, and InP

Abstract

We revisit the Fabry–Perot (FP) reflectivity method to measure optical indices in the mid-infrared spectrum. This simple approach can be readily implemented using a standard Fourier transform infrared spectrometer. Measuring samples with multiple heights allows for enhanced precision of the measurement, making the FP method consistent in values and uncertainties with more advanced ellipsometric measurements. An extensive discussion about experimental errors is carried out. Results between 4 and 12 µm for AlInAs, n-doped InGaAs, and InP, which are the most standard materials for quantum cascade lasers, are given.

Large omnidirectional mid-infrared photonic bandgap in a one-dimensional ternary photonic crystal consisting of isotropic dielectric, elliptical metamaterial and plasma

“…Now, the 1-D ternary PhC can be represented as [A(CD) 4 P] 7 , as schematically shown in figure 3. The material of plasma layer is select to be n-doped indium gallium arsenide (InGaAs) since it is a kind of low-loss plasmas at mid-infrared wavelengths [62]. The proposed structure is a multilayer containing Si, Te, PS and n-doped InGaAs layers, which can be easily fabricated by the current magnetron sputtering [37] or electron-beam deposition technique [39].…”

“…It is known that the relative permittivity of n-doped InGaAs can be well modelled as [62] ( The first term represents the background relative permittivity e ¥ . The second term originates from the free carrier absorption (FCA) with the plasma angular frequency w FCA and the scattering time g / 1 .…”

“…19 3 All the parameters can be fitted by the experimental data [62]: e = ph Figure 4 gives the dependences of the real and imaginary parts of the relative permittivity of P at normal incidence, as shown in figure 5(a). As we discussed above, the wavelength region satisfying > R 0.6 is defined as the PBG.…”