RESUMO
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.
RESUMO
We report the study of a resonant bandpass filter made of a very thin subwavelength metal patch array coupled to a high index dielectric waveguide. The spectral properties of those filters can easily be tuned by playing on the lateral dimensions of the grating. They exhibit high and narrow transmission peaks together with very good rejection of light out of the pass-band and low angular dependance. An experimental demonstration using standard large scale silicon microelectronics processes is presented in the mid infrared spectral range. This concept of filters can easily be scaled throughout the optical spectrum, and can be integrated within focal plane arrays of various imaging technologies, down to visible wavelengths.
