The whispering-gallery-mode (WGM) photonic crystal microcavity can be potentially used for miniaturized photonic devices, such as thresholdless lasers. In this paper, we use plane wave expansion (PWE) method and study the WGM of H2 photonic crystal microcavities which are formed by removing seven center air holes in a photonic crystal. The WGM in these large-size cavities has some advantages compared with single defect WGM in the view of real device applications. We analyze the nearby air hole effect on WGM and conclude that WGM is more sensitive to moving towards the outside rather than moving towards the inside of a nearby air hole. In our case, if a nearby air hole is moved 0.1a away from the center, the WGM will disappear. If a nearby air hole is moved 0.6a towards the center, however, the WGM will still exit. We also analyze the structure with an air hole (rm= 0.2a) in the center of the microcavity, and we find that the WGM is not affected by the central hole sensitively. As we increase rm, the WGM remains unchanged until rm is 0.64 times greater than period a. It is found that the tolerance of WGM to the displacement of nearby air holes and the occurance of central holes is large enough to fabricate electrical injection structure.
Alexei A. Erchak, Daniel J. Ripin, Shanhui Fan, Peter Rakich, John D. Joannopoulos, Erich P. Ippen, Gale S. Petrich and Leslie A. Kolodziejski, Appl. Phys. Lett. 78, 563 (1901).CrossRefADSGoogle Scholar
LI Heng-rui, SANG Xin-zhu, YUAN Jin-hui, WANG Kui-ru and YU Chong-xiu, Optoelectronics Letters 6, 172 (1910).CrossRefADSGoogle Scholar
LING Jing, SANG Xin-zhu, YUAN Jin-hui, WANG Kui-ru, YU Chong-xiu, XIN Xiang-jun and XU Wei, Optoelectronics Letters 6, 168 (1910).CrossRefADSGoogle Scholar