An On-Chip Calibration Method for Optical Phased Array With No Blind Spot in the Steering Range

We demonstrate an on-chip phase calibration method in the silicon-based optical phased array (OPA) using multimode interferences (MMIs) and germanium silicon photodetectors (GeSi PDs), which are integrated at the end of the grating array. Two groups of MMIs with staggered symmetrical distribution are utilized to obtain the phase difference between adjacent gratings and linked to the PDs. With this method, a
$1\times32$
OPA with thirty-two PDs realizes a
$36.4^{\circ } \,\, \times11.5^{\circ }$
beam steering range without any blind spot, and the optimal side-lobe suppression ratio is 9.3 dB.