Enhanced electromagnetic coupling between terahertz radiation and plasmons in a grating-gate transistor structure on membrane substrate.

We have shown that the electromagnetic coupling of a grating-gate plasmonic detector to terahertz radiation can be considerably enhanced by placing the detector onto a membrane substrate and using a narrow-slit grating-gate. The responsivity of the membrane detector can be enhanced by a factor of 50 as compared to a conventional grating-gate plasmonic detector on a bulk substrate due to enhanced electromagnetic coupling between the plasmons and terahertz radiation.