Silicon-Based Hybrid Integrated Photonic Chip for K_u band Electromagnetic Wave Sensing

In this paper, we experimentally demonstrate a highly sensitive on-chip photonic electromagnetic wave sensor operating at 14.1 GHz with a 3 dB bandwidth of 4.84 GHz. The demonstrated electromagnetic sensor has several important advantages over conventional electrical electromagnetic sensors, including high sensitivity, compact in size, and strong immunity to electromagnetic interference. The sensor is comprised of a bowtie antenna and an asymmetric Mach-Zehnder interferometer (MZI). One arm of the MZI is an electro-optic polymer infiltrated one-dimensional slot photonic crystal waveguide (SPCW) and the other is a strip waveguide with teeth of subwavelength pitch. Bowtie antennas are designed and optimized to effectively collect 14.1 GHz microwave signal and applies it across the SPCW. The phase of the light guided in the SPCW therefore changes, and so does the amplitude of the output end of the MZI. The sensor is only 4.6 mm × 4.8 mm in size and has a low insertion loss of ∼10 dB. Experimental results show the limit of detection at 14.1 GHz is 4.31 mW/m², which is corresponding to a minimum detectable electric field of 1.8