Ultra-broadband on-chip beam focusing enabled by GRIN metalens on silicon-on-insulator platform
Shen Jian,
Zhang Yong,
Dong Yihang,
Xu Zihan,
Xu Jian,
Quan Xueling,
Zou Xihua,
Su Yikai
Affiliations
Shen Jian
State Key Lab of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai200240, China
Zhang Yong
State Key Lab of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai200240, China
Dong Yihang
State Key Lab of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai200240, China
Xu Zihan
State Key Lab of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai200240, China
Xu Jian
Center for Advanced Electronic Materials and Devices, Shanghai Jiao Tong University, Shanghai200240, China
Quan Xueling
Center for Advanced Electronic Materials and Devices, Shanghai Jiao Tong University, Shanghai200240, China
Zou Xihua
Center for Information Photonics and Communications, School of Information Science and Technology, Southwest Jiao Tong University, Chengdu611756, China
Su Yikai
State Key Lab of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai200240, China
Metalens has emerged as an important optical block in free-space optical systems, which shows excellent performance. Even the metalens based on gradient index (GRIN) profiles can be implemented for on-chip beam focusing behavior. However, for most previous schemes, the GRIN metalenses can only achieve on-chip beam focusing behavior in one dimension, which limits their applications in low-loss waveguide interconnecting or fiber-to-chip coupling. In this paper, an on-chip half Maxwell’s fisheye lens based on GRIN profiles with subwavelength features, integrated with silicon waveguides, is experimentally demonstrated. Benefitting from the index distribution and beam focusing characteristics of the half Maxwell’s fisheye lens, an on-chip beam transforming can be achieved for transverse electric (TE) fundamental mode in two waveguides with different heights and widths. The simulated 1 dB bandwidth can reach 1100 nm, which exhibits great prospects in integrated photonic circuits. The measured insertion loss of an on-chip 5.4 μm-length lens is less than 1 dB to connect a 220 nm-height, 8 μm-wide waveguide, and a 60 nm-height, 0.5 μm-wide waveguide in the wavelength range of 1280–1620 nm.
