Optical Beam Expander With Parabolic Photonic Bandgap Reflector for Efficient Excitation of Optical Leaky Wave Antenna

This paper proposes and demonstrates an optical leaky wave antenna (OWLA) excited by a beam expander consisting of a slab waveguide and parabolic photonic bandgap (PBG) reflector. Conventional OLWAs are usually excited through an adiabatic taper waveguide, but its large size is a drawback. The PBG reflector is easy to fabricate with the OLWA using Si photonics technology and its size is ten times smaller than that of the adiabatic taper waveguide. We confirmed the excitation of a shallow grating waveguide, which is a kind of OLWAs, through the beam expander in simulations and measurements.