Dielectric silicon slot-waveguides for far-infrared THz-spectroscopy

We present the design and characterization of dielectric slot waveguides fabricated in highly resistive silicon for operation in the THz frequency range. We designed rib and slot waveguides with straight and curved beams using the mode solvers from BeamPROP and CST Studio Suite. The transmission parameters of the free space measurement is about -30 dB. Using the slot waveguide, the transmission is about -15 dB demonstrating the ability to guide fields in our structures. At 300 GHz, the measured losses are in the range of 0.15 dB/mm. Solvents are injected into the slot of the waveguide by capillary force changing the transmission. Each solvent realizes a different change in transmission, so that we aim to use the slot waveguides for THz spectroscopy in future.