Low‐noise heterodyne detection of terahertz waves at room temperature using zero‐biased Fermi‐level managed barrier diode

Abstract

A Fermi-level managed barrier (FMB) diode was used for the heterodyne detection of terahertz waves for the first time. A quasi-optical module integrating an FMB diode and a broadband trans-impedance amplifier exhibited an intermediate frequency bandwidth of 11 GHz. A very low noise-equivalent-power of 1.1 × 10 −18 W/Hz was achieved at ∼300 GHz with a very low local oscillator power of 6 × 10 −6 W.

Low‐local‐oscillator‐power sub‐harmonic mixing in 300‐GHz band by Fermi‐level managed barrier diode

“…The fabricated chip was then assembled in a quasi‐optical package [4, 5 ] with a trans‐impedance amplifier (TIA) (Semtech, GN1068, bandwidth: 11.8 GHz). The FMB diode was zero‐biased in the circuit and only the TIA was biased at +3.3 V. For the SHM characterisation, input and LO signals were generated by photo mixing using heterodyning signal sources based on optical frequency‐comb generators [7 ] and two types of waveguide‐output uni‐travelling‐carrier photodiode modules [8, 9 ].…”

“…The low‐barrier height is important both for decreasing the diode differential resistance and increasing the diode current density to achieve high‐frequency and low‐noise signal detection at a zero‐bias condition. We demonstrated that FMB diodes had very low‐noise characteristics with very low LO powers in the fundamental mixing mode [5, 6 ]. Thus, it is of great interest to investigate SHM by the FMB diode to clarify its performance and guidelines to optimise its structure as a sub‐harmonic mixer.…”

Subcarrier Frequency-Modulated Continuous-Wave Radar in the Terahertz Range Based on a Resonant-Tunneling-Diode Oscillator

“…After propagating through air, the beam is focused by a second plastic lens onto a detector. We used a Fermi-level-managed-barrier-diode (FMBD) detector [17], which in our particular setup turned out to have a signal-to-noise ratio about 10 dB better than another high-speed terahertz-wave detector that we tried, namely a Schottky-barrier-diode (SBD) detector.…”

300 GHz optical waveform measurement by novel THz‐wave autocorrelator

“…These waveforms are converted into THz waveforms by the unitraveling‐carrier photodiodes (UTC‐PDs) [4]. They are coupled by a THz beam combiner and the power is detected by the Fermi‐level managed barrier diode (FMB‐D) [5], so that the autocorrelation of the original optical waveform can be observed as a function of the delay. In this experiment, we used 100, 200 and 300 GHz sinusoidally modulated waves which were generated as beat signals from two lightwaves (LD1, LD2) with an optical frequency difference of 100, 200 and 300 GHz.…”