Sub-wavelength pitch optical antenna array with low crosstalk for optical phased array

Electromagnetic couplings are ubiquitous in the microwave and optical systems. Notably, high-density integration of photonic chips will suffer from strong crosstalk between different channels due to the larger electrical size of dielectric waveguides, resulting in the degradation of device performance. For the application of optical phased arrays (OPAs), strong crosstalk between adjacent channels will prevent the independent phase control over each antenna element. Here, we propose a sub-wavelength pitch optical antenna array with low crosstalk for wide-angle beam steering of OPA. In this design, two thin strips along the transmission waveguide are introduced to increase the cladding anisotropy, suppressing evanescent wave couplings. Besides, period nano-blocks arranged along both sides of silicon strip waveguide are utilized to suppress the crosstalk further and radiate electromagnetic waves into free spaces simultaneously.