Fig. 1
From: Compact and ultra-efficient broadband plasmonic terahertz field detector
On-chip terahertz detector. a The detector consists of a Mach–Zehnder interferometer (MZI) with antenna-coupled plasmonic phase shifters (PPS). An incident THz field (ETHz,i) introduces, via the linear electro-optic effect, a refractive index change in the gap of the two antenna-coupled phase shifters. This change of refractive index leads to a linear phase delay (±ΔφTHz) of the IR probe pulses (IIR) traveling through the phase shifters. The phase modulation experienced by the IR probe pulses is transformed into an intensity modulation (IIR+THz) at the output of the interferometer. The probe pulses are coupled in and out on-chip silicon (Si) waveguides by means of grating couplers (GC). The organic electro-optic material in the two-phase shifters located in opposite arms of the MZI has opposite polarity to enable push-pull operation. Scale bar is 10 μm. b False color scanning electron image of the fabricated multi-resonant THz detector. The antenna comprises of a high-frequency (HF) antenna and a low-frequency (LF) antenna. Each antenna is resonant within a spectral range. Combined they provide a broadband THz response. c Close-up view of the HF-THz antenna directly coupled to the PPS. Scale bar is 2 μm. SMF single mode fiber, 50:50: multi-mode interferometer.
