We discuss the light pulse propagation in a one-dimensional photonic crystal doped by graphene quantum dots in a defect layer. The graphene quantum dots behave as a three-level quantum system and are driven by three coherent laser fields. It is shown that the group velocity of the transmitted and reflected pulses can be switched from subluminal to superluminal light propagation by adjusting the relative phase of the applied fields. Furthermore, it is found that by proper choice of the phase difference between applied fields, the weak probe field amplification is achieved through a one-dimensional photonic crystal. In this way, the result is simultaneous subluminal transmission and reflection.

In this paper, a compact and diffraction limited heads up display (HUD) image source is presented. The great benefit of this design is its diffraction limited optic, compacted structure, economic considerations, simplicity in manufacturing and high efficiency image quality. The innovation of this design is the use of a polarization grating-polarization conversion system (PG-PCS). This module transforms the unpolarized Gaussian beam to a linearly polarized beam and it simultaneously homogenizes the spatial intensity profile. With this module, it is possible to increase the efficiency of illumination and to utilize the ordinary micro LCD instead of using a digital micro mirror device (DMD) and liquid crystal on silicon (LCOS) micro displays. The diameter of the image plane is 76.2 mm (in accordance with conventional types). Our design yielded uniform illuminated image and its high efficiency facilitates display readability in see-through HUDs operating in high ambient light as well as low ambient light.

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