DEVELOPMENT OF TUNABLE LOCAL OSCILLATOER OF THZWAVE BY PHOTOMIXING EXCITATION

本项目研究了光子-微波转换材料中的超快载流子动力学，并基于新思想开发了一种高度可控、稳定的可调谐振荡器和光子-微波转换器。我们成功地观察了几种高温高温合金和锰氧化物的太赫兹辐射。发现在弱磁场下，TBCCO可以光激发约瑟夫森等离子体发射。在时域上观察载流子动力学。太赫兹光谱。结果表明，由于超导体与衬底界面处的太赫兹反射减弱，氧还原高温超导材料的太赫兹发射强度明显增强。我们还观察到a-Ge的太赫兹辐射和超快光响应。结果表明，在波长为1.55μm的光源下，a- ge具有作为光混合激发材料的潜力。我们通过制作光混合器和高温超导约瑟夫森结的混合装置，研制了一种光子-微波转换器，并成功地产生和检测了高达200 GHz的微波。我们证明了利用该装置产生的微波具有高度的可控性和稳定性。我们提出这种光子-微波转换器作为一种潜在的检测精确波长的系统。我们还提出了一种光控太赫兹磁通晶体管，作为光通信信号与单磁通量子逻辑电路之间的光直接接口。制作了初步装置，并在光激发下进行了测试。这一成果开辟了“超导体光子学”的新研究领域，将为太赫兹技术提供关键突破。

This project investigates ultrafast carrier dynamics in photon-microwave conversion materials, and develops a highly controllable and stable tunable oscillator and photon microwave converter based on new idea.We successfully observed THz radiation from several kinds of HTSs and Mn oxides. It was discovered that Josephson plasma emission can be optically-excited for TBCCO under weak magnetic field. The carrier dynamics was observed by time domain. THz spectroscopy. It was found that oxygen reduced HTS strongly enhances the THz emission intensity due to the decrease in THz reflection at the interface between superconductors and substrate.We also observed THz radiation and ultrafast photo-response of a-Ge. It was found that a-Ge has potential as a photomixing excitation material for the use of light source with 1.55μm wavelength.We developed a photon-microwave converter by fabricating the hybrid device of photo-mixer and HTS Josephson junction, and succeeded in the generation and detection of the microwaves extending up to 200 GHz. We demonstrated the high controllability and stability of the microwaves generated by using the fabricated devices. We proposed this photon-microwave converter as a potential system to detect accurate optical wavelength.We also proposed an optically-controlled-terahertz flux-flow transistor as an optical direct interface between optical communication signals and single flux quantum logic circuits. The preliminary device was fabricated and tested under optical excitation.The results obtained here has opened new research field "Superconductor Photonics", which will provide a key breakthrough for terahertz technology.