A comprehensive review considering recent advances in self-collimation and its applications in optical integration is covered in the current article. Self-collimation is compared to the conventional technique of photonic bandgap engineering to control the light propagation in photonic crystal-based structures. It is fully discussed how the self-collimation phenomenon can be tailored to be independent of the incident angle and polarization. This adds substantial flexibility to the structure to overcome light coupling challenges and simultaneously aids in the omission of bulk and challenging elements, including polarizers and lenses from optical integrated circuits. Additionally, designed structures have the potential to be rescaled to operate in any desired frequency range thanks to the scalability rule in the field of electromagnetics. Moreover, it is shown that one can boost the coupling efficiency by applying an anti-reflection property to the structure, which provides not only efficient index matching but also the matching between external waves with uniform amplitude and Bloch waves with periodic amplitude.
A comprehensive study has been performed to achieve all-angle self-collimation in basic two-dimensional square array photonic crystals with cylindrical scatterers. Based on plane wave expansion and finite difference time domain analysis for both rod-and hole-type structures, we report on all-angle self-collimation (SC) in the first band of the structure, which results in loss suppression due to out-of-plane scatterings. A lower threshold for index contrast has been obtained to achieve all-angle SC, which offers more design flexibility regarding structural parameters. Furthermore, it has been shown that a minimum and maximum coupling efficiency enhancement of ∼40% and 80% can be achieved for the proposed structure, respectively, by introducing a row of scatterers with proper radius at the input and the output air/photonic crystal interfaces. Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Optical Engineering 037111-2 March 2015 • Vol. 54(3) Noori, Soroosh, and Baghban: All-angle self-collimation in two-dimensional square array photonic crystals. . . Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Mina Noori received her BS and MS degrees in electronics engineering (optical integrated circuits) from University of Tabriz, Iran, in 2010 and 2012, respectively. She is currently working toward her PhD degree at Shahid Chamran University, Ahvaz, Iran, and her current research interest includes photonic crystal devices and structures. Mohammad Soroosh received his MS and PhD degrees in electronics engineering from Tarbiat Modares University, Tehran,
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