title: Nonlinear optical detection of terahertz-wave radiation from resonant tunneling diodes.
abstract: The sensitive detection of terahertz (THz)-wave radiation from compact sources at room temperature is crucial for real-world THz-wave applications. Here, we demonstrate the nonlinear optical detection of THz-wave radiation from continuous-wave (CW) resonant tunneling diodes (RTDs) at 0.58, 0.78, and 1.14 THz. The up-conversion process in a MgO:LiNbO3crystal under the noncollinear phase-matching condition offers efficient wavelength conversion from a THz wave to a near-infrared (NIR) wave that is detected using a commercial NIR photodetector. The minimum detection limit of CW THz-wave power is as low as 5 nW at 1.14 THz, corresponding to 2-aJ energy and 2.7 × 103photons within the time window of a 0.31-ns pump pulse. Our results show that the input frequency and power of RTD devices can be calibrated by measuring the output wavelength and energy of up-converted waves, respectively. This optical detection technique for compact electronic THz-wave sources will open up a new opportunity for the realization of real-world THz-wave applications.
authors.forename: Yuma
authors.initials: Y
authors.lastname: Takida
authors.forename: Kouji
authors.initials: K
authors.lastname: Nawata
authors.forename: Safumi
authors.initials: S
authors.lastname: Suzuki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Asada
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Minamide