1. The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057 Guangdong China
2. Department of Electronic and Information EngineeringThe Hong Kong Polytechnic University Hong Hum Hong Kong 999077 China
3. Department of PhysicsThe Chinese University of Hong Kong New Territories Hong Kong 999077 China
4. Department of Applied PhysicsThe Hong Kong Polytechnic University Hong Hum Hong Kong 999077 China