This paper proposes an extended M-sequence/extended perfect difference (EMS/EPD) code family which can be applied to a two-dimensional (2-D) spectral/spatial (SS) fiber-optic code division multiple access (FO-CDMA) passive optical network (PON) with interference elimination. In addition, the proposed code family can effectively suppress the effect of phase-induced intensity noise (PIIN) and has a flexible size and the cyclic property. By using an extending technique, the number of fibers is substantially reduced between the remote node (RN) and the optical network units (ONUs). Furthermore, we design a compact optical line terminal (OLT) using the arrayed waveguide grating (AWG) router at the central office (CO) and simple ONUs using the thin-film filters (TFFs) at end users. Based on the mathematical analysis and numerical results, the 2D SS EMS/EPD code family is suitable for high-rate transmission with very good performance.

This work proposes a simple and effective strategy for photon clustering, called regional photon clustering, to accelerate the global illumination updating of dynamic scenes. This method can cluster various numbers of photons adaptively. The scenes in adjacent frames are similar, and so most photons have the same moving paths in adjacent frames. Therefore, most photons do not need to be shot again in the next frame. Regional photon clustering employs a quadtree structure to track the trajectory of dynamic objects to reduce the number of re-shot photons. Experimental results show that regional photon clustering reduces the number of re-shot photons, and accelerates the estimation of global illumination in dynamic scenes