1. School of Information and Optoelectronic Science and Engineering & South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 China
2. School of Materials Science and EngineeringTianjin Key Laboratory of Materials Laminating Fabrication and Interface Control TechnologyHebei University of Technology Tianjin 300130 China
3. Department of Chemical EngineeringUniversity of Waterloo Waterloo ON N2L 3G1 Canada
4. Department of PhysicsBoston College Chestnut Hill MA 02467 USA