In this article, we investigated the possibility of achieving all- angle, polarization insensitive and broad band self- collimation simultaneously in a same structure, which is one of the most recently introduced urgent requirements in the field of optical integration. In order to fulfill these three attractive properties in 2D square array photonic crystals, different strategies are used and a comprehensive analysis using Plane Wave Expansion and Finite Difference Time Domain methods are done. Here, the main attempt was to save the structure’s simple geometry and not to complicate the basic structure. So in order to get all- angle self- collimation, we had to use relatively high index material (n=6) for hole type structure which shows less dependency on polarization. The optimized structure has a frequency range of 2.6%, supporting all-angle self- collimation for both polarizations achieved to the expense of small deviation of 30 in collimation direction from ideal case, although it will not cause any significant problem for small sized devices in the field of optical integration.  Manuscript profile

In this paper, we used photonic crystal resonant cavity structure for designing a 2-channel optical wavelength demultiplexer. It has been shown that by using photonic crystal resonant cavity, wavelength separation is possible. In order to select 2 channels with different central wavelengths we employed 2 resonant cavities with different structural parameters. The platform used for designing the proposed demultiplexer is a hexagonal lattice of dielectric rods immersed in air. The demultiplexer has 2 channels with central wavelengths equal to l1=1549.4 nm and l2=1551.2 nm. The transmission efficiency of the demultiplexer is more than 92%. The quality factors for first and second channels are 1936 and 3021 respectively. Manuscript profile