Frequency-tunable resonant-tunneling-diode terahertz oscillators applied to absorbance measurement

Abstract

We show that frequency-tunable terahertz oscillators with resonant-tunneling diodes (RTDs) can be applied to absorbance measurement, using allopurinol as a specimen, which has a characteristic absorption spectra at around 700 GHz. The RTD oscillators used in this experiment are seven elements covering from 420 to 970 GHz. The result was in good agreement with that of time-domain spectroscopy usually used in the terahertz frequency region.

1.0–10.0 THz Radiation from Graphene Nanoribbon Based Avalanche Transit Time Sources

“…Those are found to be very inefficient sources having DC to RF conversion efficiency of less than 1% within the above‐mentioned frequency range. Among the solid‐state terahertz radiators, RTD oscillators are capable of delivering 0.1–5.0 µW power within the frequency range of 0.42–0.97 THz . Other sources like cascaded frequency multipliers deliver 10–2 µW power at 1.9–2.7 THz .…”

“…However, in recent years the extensive research and development is going on throughout the world in order to realize suitable solid‐state source capable of generating, detecting and processing the terahertz signals with appreciable power required for system applications. Some examples of terahertz sources are electron beam sources, optically pumped far‐infrared gas lasers, semiconductor quantum cascade lasers (QCLs), resonant tunneling diodes (RTDs), high electron mobility transistors (HEMTs), heterojunction bipolar transistors (HBTs), etc . However, most of the above‐mentioned terahertz generators are either very complex in nature and non‐operational at room temperature or bulky.…”

“…However, most of the above‐mentioned terahertz generators are either very complex in nature and non‐operational at room temperature or bulky. Moreover, those are limited by the amount of power output and efficiency; e.g., 0.1–5.0 µW of power output is available from frequency‐tunable RTD terahertz oscillators covering from 0.42 to 0.97 THz . Another solid‐state device has been successfully implemented recently which can generate terahertz frequency at room temperature; it is cascaded frequency multipliers which is capable of delivering 10–2 µW power at 1.9–2.7 THz frequency range …”

Broken Symmetry Effects due to Polarization on Resonant Tunneling Transport in Double-Barrier Nitride Heterostructures

“…The possibility of engineering transport dynamics, combined with their characteristic negative differential conductance (NDC), make RTDs attractive for manufacturing ultra-fast electronic oscillators [3][4][5]. With oscillation frequencies well inside the terahertz (THz) band, RTDs stand out as viable sources of THz radiation, employed in practical applications such as high data-rate communication networks and on-chip spectroscopy systems [6][7][8].…”

Three‐Terminal Graphene Nanoribbon Tunable Avalanche Transit Time Sources for Terahertz Power Generation

“…Still now, the THz‐gap (0.3–10.0 THz) is considered as an unexploited frequency spectrum due to the unavailability of commercial THz source . Some solid‐state sources such as quantum cascade lasers (QCLs), resonant tunneling diodes (RTDs), high‐electron‐mobility transistor (HEMT), and heterojunction bipolar transistors (HBTs) are capable of generating THz waves at room temperature . However, those are limited in output power; only a few microwatts (μW) of THz power can be delivered by those.…”