Nonequilibrium Green's function (NEGF) calculations of mid-infrared quantum cascade laser (QCL) that preserve real-space basis have been performed. The approach developed in this paper relies on two improvements introduced to nonequilibrium Green's functions/Poisson computational scheme. First, the boundaries of single laser stage were carefully designed as to maintain its periodicity with the whole quantum cascade structure. Second, the NEGF/Poisson solver was equipped with several controlling features that enable the restoration of convergence of the method for quite complex structures with many resonances and boundary conditions for Poisson equation set inside the structure. With this simulation tool, calculations for an anticrossed diagonal design of mid-infrared QCL have been performed. Results agree with experimental data (threshold current of ~4.2 kA/cm² at material gain of ~70/cm) and the current understanding of carrier transport in such devices.

Features of glass transition in liquid crystalline nematic and smectic E, B and I_A phases of selected materials observed by means of the polarising microscopy and Fourier transform infrared spectroscopy (FTIR) are reported. Evolution of cracking in the glass and a coincidence of its disappearance temperature with the glass transition temperature (T_g) on heating is shown and discussed in the context of processes that occur in the glass. The shape of temperature dependencies of absorption bands is shown as the signature of the glass transition.