Millimeter wave photonic crystal waveguides fabricated via direct machining

At the moment, millimeter waves attract close attention not only of the scientific community, but also of the communication industry. Number of studies worldwide are currently focused on finding efficient solutions for the transceiver technologies compatible with beamforming and carrier frequencies beyond 100 GHz. It was recently demonstrated that the technology of integrated silicon photonic crystals provides decent propagation loss and low fabrication complexity upon implementation of waveguide components for the submmWave band. In this paper, we report on the millimeter wave photonic crystal waveguides fabricated from high permittivity PCB laminate by the means of direct machining. Inspection of the fabricated waveguide samples reveals no violation of the photonic crystal geometry due to the fabrication tolerances. The photonic crystals are designed for operation at frequencies 140–160 GHz, and we measure the power attenuation coefficient attributed to the waveguide geometry of 0.02 dB/mm at 145 GHz. The design considerations, including justification of the laminate choice, and detailed results of performance tests are presented in the paper.