Martin Muthee

Antenna Enhanced Graphene THz Emitter and Detector

Recent intense electrical and optical studies of graphene have pushed the material to the forefront of optoelectronic research. Of particular interest is the few terahertz (THz) frequency regime where efficient light sources and highly sensitive detectors are very challenging to make. Here we present THz sources and detectors made with graphene field effect transistors (GFETs) enhanced by a double-patch antenna and an on-chip silicon lens. We report the first experimental observation of 1-3 THz radiation from graphene, as well as more than 3 orders of magnitude performance improvements in a half-edge-contacted GFET thermoelectric detector operating at ∼2 THz. The quantitative analysis of the emitting power and its unusual charge density dependence indicate significant nonthermal noise contribution from the GFET. The polarization resolved detection measurements with different illumination geometries allow for detailed and quantitative analysis of various factors that contribute to the overall detector performance. Our experimental results represent a significant advance toward practically useful graphene THz devices.

Antenna-coupled terahertz radiation from joule-heated single-wall carbon nanotubes

In this letter an experimental method is introduced that allows detection of terahertz (THz) radiation from arrays of joule-heated Single-Walled Carbon Nanotubes (SWCNTs), by coupling this radiation through integrated antennas and a silicon lens. The radiation forms a diffraction-limited beam with a total maximum radiated power of 450 nW, significantly greater than the power estimated from Nyquist thermal noise (8 nW). The physical radiation process is unknown at this stage, but possible explanations for the high radiated power are discussed briefly. The emission has a typical bandwidth of 1.2 THz and can be tuned to different frequencies by changing the dimensions of the antennas. Arrays of the devices could be integrated in CMOS integrated circuits, and find application in THz systems, such as in near-range medical imaging.

Microwave and terahertz detection in bundles of single-wall carbon nanotubes

We present new data on microwave detection in bundles of carbon nanotubes (CNTs). In particular, we derive a circuit model based on ANA measurements. We also demonstrate the first terahertz detection (up to 2.54 THz) in bundles of CNTs that were deposited through dielectrophoresis across the smallest gap in log-periodic antennas. Data are given that support the hypothesis that the detection process is bolometric at THz frequencies. Future extensions are planned that will employ suspended CNTs and explore heterodyne detection. Finally, we have performed unique ab initio simulations of CNTs with the aim of comparing these with the experimental data.