Abstract-Nonlinear optical detection of terahertz-wave radiation from resonant-tunneling-diode oscillators

 Yuma Takida,  Kouji Nawata,  Safumi Suzuki,,   Masahiro Asada,  Hiroaki Minamide,

http://ieeexplore.ieee.org/document/8086431/

The sensitive detection of terahertz (THz)-wave radiation from compact sources at room temperature is crucial for real-world THz-wave applications, such as non-destructive inspection and homeland security. As an extremely compact THz-wave source, the resonant-tunneling-diode (RTD) oscillator is a particular important electronic device operating in the THz-wave frequency region. The oscillation frequency of RTD is now close to 2 THz with improvements in their structures [1]. For detecting THz-wave radiation from RTDs at room temperature, frequency up-conversion in nonlinear optical crystals is a promising technique because the input frequency and power of RTD can be calibrated by measuring the output wavelength and energy of up-converted waves, respectively. In the up-conversion process, the THz-wave radiation (ωthz) is mixed with an optical pump wave (ωp) in a nonlinear crystal to generate an optical up-converted wave (ωup) according to the energy conservation law (ωp = ωup + ωthz) [2, 3]. The generated up-converted wave is detected using a commercial photodetector with nanosecond resolution. This optical approach differs from conventional room-temperature THz-wave direct detectors, such as the pyro-electric detector and Golly cell, which offer slow response time on the order of millisecond.

Abstract-Terahertz communications using resonant-tunneling-diode oscillators

SafUmi Suzuki,  Masahiro Asada,

http://ieeexplore.ieee.org/document/7928431/

The recent progress in terahertz wireless data transmissions using resonant-tunneling-diode (RTD) oscillators is reported. RTD oscillators with wide modulation bandwidth (∼30 GHz) were fabricated, and wireless data transmissions in the 500-GHz range were demonstrated. An error-free transmission data rate up to 22 Gbps and a transmission with bit error rate less than the forward error correction limit, up to 34 Gbps, were achieved. For alignment-free wireless communication in the polarization direction, an RTD oscillator integrated with a radial line slot antenna for circular-polarized radiation was proposed and fabricated. A sharp directivity and low axial ratio of polarization (2.2 dB) was achieved at 710 GHz.