1. Wuhan National Laboratory for Optoelectronics, Optics Valley Laboratory, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, China, 430074
2. State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050, China
3. NIH Resource Center for Medical Ultrasonic Transducer Technology, Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA