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18 results on '"Mao, Qiuping"'

2. Dirac-Point Solitons in Nonlinear Optical Lattices

Author

Xie, Kang, Li, Qian, Boardman, Allan D., Guo, Qi, Shi, Zhiwei, Jiang, Haiming, Hu, Zhijia, Zhang, Wei, Mao, Qiuping, Hu, Lei, Yang, Tianyu, Wen, Fei, and Wang, Erlei

Subjects
Physics - Optics
Abstract

The discovery of a new type of solitons occuring in periodic systems without photonic bandgaps is reported. Solitons are nonlinear self-trapped wave packets. They have been extensively studied in many branches of physics. Solitons in periodic systems, which have become the mainstream of soliton research in the past decade, are localized states supported by photonic bandgaps. In this Letter, we report the discovery of a new type of solitons located at the Dirac point beyond photonic bandgaps. The Dirac point is a conical singularity of a photonic band structure where wave motion obeys the famous Dirac equation. These new solitons are sustained by the Dirac point rather than photonic bandgaps, thus provides a sort of advance in conceptual understanding over the traditional gap solitons. Apart from their theoretical impact within soliton theory, they have many potential uses because such solitons have dramatic stability characteristics and are possible in both Kerr material and photorefractive crystals that possess self-focusing and self-defocusing nonlinearities. The new results elegantly reveal that traditional photonic bandgaps are not required when Dirac points are accessible. The findings enrich the soliton family and provide valuable information for studies of nonlinear waves in many branches of physics, including hydrodynamics, plasma physics, and Bose Einstein condensates.

Published
2015

7. Experimental observation of wave localization at the Dirac frequency in a two-dimensional photonic crystal microcavity

Author

Hu, Lei, Xie, Kang, Hu, Zhijia, Mao, Qiuping, Xia, Jiangying, Jiang, Haiming, Zhang, Junxi, Wen, Jianxiang, Chen, Jingjing, Hu, Lei, Xie, Kang, Hu, Zhijia, Mao, Qiuping, Xia, Jiangying, Jiang, Haiming, Zhang, Junxi, Wen, Jianxiang, and Chen, Jingjing

Abstract

Trapping light within cavities or waveguides in photonic crystals is an effective technology in modern integrated optics. Traditionally, cavities rely on total internal reflection or a photonic bandgap to achieve field confinement. Recent investigations have examined new localized modes that occur at a Dirac frequency that is beyond any complete photonic bandgap. We design Al2O3 dielectric cylinders placed on a triangular lattice in air, and change the central rod size to form a photonic crystal microcavity. It is predicted that waves can be localized at the Dirac frequency in this device without photonic bandgaps or total internal reflections. We perform a theoretical analysis of this new wave localization and verify it experimentally. This work paves the way for exploring localized defect modes at the Dirac point in the visible and infrared bands, with potential applicability to new optical devices.

Published
2018

10. Spatial algebraic solitons at the Dirac point in optically induced nonlinear photonic lattices

Author

Xie, Kang, Boardman, Allan D., Li, Qian, Shi, Zhiwei, Jiang, Haiming, Xia, Hongyan, Hu, Zhijia, Zhang, Junxi, Zhang, Wei, Mao, Qiuping, Hu, Lei, Yang, Tianyu, Wen, Fei, Wang, Erlei, Xie, Kang, Boardman, Allan D., Li, Qian, Shi, Zhiwei, Jiang, Haiming, Xia, Hongyan, Hu, Zhijia, Zhang, Junxi, Zhang, Wei, Mao, Qiuping, Hu, Lei, Yang, Tianyu, Wen, Fei, and Wang, Erlei

Abstract

The discovery of a new type of soliton occurring in periodic systems is reported. This type of nonlinear excitation exists at a Dirac point of a photonic band structure, and features an oscillating tail that damps algebraically. Solitons in periodic systems are localized states traditionally supported by photonic bandgaps. Here, it is found that besides photonic bandgaps, a Dirac point in the band structure of triangular optical lattices can also sustain solitons. Apart from their theoretical impact within the soliton theory, they have many potential uses because such solitons are possible in both Kerr material and photorefractive crystals that possess self-focusing and self-defocusing nonlinearities. The findings enrich the soliton family and provide information for studies of nonlinear waves in many branches of physics.

Published
2017

11. Fiber guiding at the Dirac frequency beyond photonic bandgaps

Author

Xie, Kang, Zhang, Wei, Boardman, Allan D., Jiang, Haiming, Hu, Zhijia, Liu, Yong, Xie, Ming, Mao, Qiuping, Hu, Lei, Li, Qian, Yang, Tianyu, Wen, Fei, and Wang, Erlei

Subjects
Physics::Optics
Abstract

Light trapping within waveguides is a key practice of modern optics, both scientifically and technologically. Photonic crystal fibers traditionally rely on total internal reflection (index-guiding fibers) or a photonic bandgap (photonic-bandgap fibers) to achieve field confinement. Here, we report the discovery of a new light trapping within fibers by the so-called Dirac point of photonic band structures. Our analysis reveals that the Dirac point can establish suppression of radiation losses and consequently a novel guided mode for propagation in photonic crystal fibers. What is known as the Dirac point is a conical singularity of a photonic band structure where wave motion obeys the famous Dirac equation. We find the unexpected phenomenon of wave localization at this point beyond photonic bandgaps. This guiding relies on the Dirac point rather than total internal reflection or photonic bandgaps, thus providing a sort of advancement in conceptual understanding over the traditional fiber guiding. The result presented here demonstrates the discovery of a new type of photonic crystal fibers, with unique characteristics that could lead to new applications in fiber sensors and lasers. The Dirac equation is a special symbol of relativistic quantum mechanics. Because of the similarity between band structures of a solid and a photonic crystal, the discovery of the Dirac-point-induced wave trapping in photonic crystals could provide novel insights into many relativistic quantum effects of the transport phenomena of photons, phonons, and electrons.

Published
2015

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