High-responsivity and polarization-discriminating terahertz photodetector based on plasmonic resonance

In this paper, a high-responsivity terahertz quantum well photodetector based on plasmonic resonance is proposed and investigated theoretically and experimentally, and the polarization-discriminating detection of the device is demonstrated. With a one-dimensional metallic grating structure integrated on the top of the detector, a 6-fold enhancement of the peak responsivity about 0.82 A/W at 46 μm compared to that of the standard device has been achieved. The physical mechanism behind the enhanced responsivity can be attributed to the enhancement of the intersubband absorption resulting from the surface Plasmon polariton mode, which can be explored from the theoretical simulation results. The polarization extinction ratio of the plasmonic-enhanced device reaches 56, and the measured signal intensity at each polarization angle satisfies Malus' law. In addition to the above advantages, the structure is simple in fabrication and compatible with the preparation process of the focal plane array. The results open up an effective method for the application of surface plasmon in terahertz detection.