Experimental Demonstration of Directive Si3N4 Optical Leaky Wave Antennas With Semiconductor Perturbations

Directive optical leaky wave antennas (OLWAs) fabricated in CMOS-compatible semiconductor planar waveguide technology have the potential to provide high directivity with electrical tunability promising for modulation and switching capabilities. We experimentally demonstrate directive radiation from a silicon nitride (Si
₃
N
₄
) waveguide-based OLWA. The OLWA design comprises a crystalline silicon (Si) nanowire array buried inside a Si
₃
N
₄
waveguide. Each Si nanowire has a width of 260 nm and a height of 150 nm. The OLWA is designed to exhibit a directive radiation pattern at telecom wavelengths. The measured radiation pattern at the wavelength 1550 nm has its maximum emission intensity at the angle of 85.1° relative to the waveguide axis and a half-power beam width of approximately 5.0°, which are consistent with our theoretical predictions. The results indicate that the TM mode is more radiative than the TE mode in our fabricated devices. Also, the radiation pattern of the measured OLWA shows dependence on wavelength, which is typical of leaky wave antennas. The device is promising in chip-to-space optical interconnect applications.