THz Output Power Research Articles

높은 출력의 THz 포토믹서를 위한 네잎클로버 형태의 안테나

테라헤르츠 광원인 포토믹서의 출력을 향상시키기 위하여 강한 공진의 복사부와 안정적인 DC 급전부로 구성된 네잎클로버 형태의 새로운 안테나구조를 제안하였다. 먼저 복사환경을 단순화시킨 무한기판 위에서 제안한 안테나구조의 공진특성을 살펴보았고, 이를 바탕으로 제안한 구조가 확장형 반구렌즈 위에서 최대의 전체효율과 지향성을 지니도록 설계하였다. 기존의 전파장다이폴안테나와 비교한 결과, 제안한 구조는 공진주파수에서 6배 이상의 높은 입력임피던스 특성을 가짐으로써 포토믹서와의 부정합효율을 크게 개선시켰으며, 이로 인해 테라헤르츠 출력이 전파장 다이폴의 경우보다 2.7배 높게 예상되었다. To improve the output power of a photomixer as a THz source, we propose a four-leaf clover-shaped antenna structure which is composed of a highly resonant radiation element and a stable DC feed element. The resonance characteristics of the proposed structure were investigated on a half-infinite substrate first as a simplified radiation environment in order to save the computation time. Based on the antenna characteristics on a half-infinite substrate, the antenna structure was designed to have a maximum total efficiency and a maximum directivity on an extended hemispherical lens. In comparison with a full-wavelength dipole, an input resistance of this structure increased six fold and this characteristic significantly improved the mismatch efficiency between a photomixer and an antenna. THz output power from this structure is expected to increase by 2.7 times as compared to a full-wavelength dipole case.

Plasmon-resonant Microchip Emitters and Their Applications to Terahertz Spectroscopy

This paper reviews recent advances in emission of THz radiation from our original dual-grating gate high-electron mobility transistors (HEMT's) originated from two-dimensional plasmons. The dual grating gates can alternately modulate the 2D electron densities to periodi- cally distribute the plasmonic cavities along the channel, acting as an antenna. The sample was fabricated with standard GaAs-based heterostructure material systems, succeeding in emission of broadband (0.5 to 6.5THz) radiation even at room temperature from self-oscillating 2D plas- mons under appropreate DC-bias conditions. Currently maximum available THz output power is estimated to be on the order of 1 to 10W from a single die active area of 75 £ 75m 2 with an excellent power conversion e-ciency of 10 i3 . The fabricated device was introduced to the Fourier-transform infrared spectroscopy as a microchip THz source. Water-vapor absorption spectrum was successfully observed at 300K, which is proven to the standard data provided by NASA.