Generation of microwave signal by using difference frequency generation in LiTaO_3 microwave rectangular waveguide

摘要

We have proposed the generation of microwave signal and the detection of high-speech optical modulation signal by using difference frequency generation in LiTaO_3 microwave rectangular waveguide. Quasi-phase-matching technique by using a periodically-poled structure is applicable for getting high conversion efficiency. A resonance effect by constructing a Fabry-Perot cavity is also attractive for improving the conversion efficiency. In the experiment using the fabricated proto-type device, the 15GHz signal was clearly observed. The measured frequency response of this signal was in good agreement with the theoretically expected frequency response. In addition, a microwave lens was used for coupling between the fabricated device and a measuring antenna. As a result, the observed signal was enhanced compared with the one without the lens. We expect this generation scheme to be applicable for detecting optical modulation signals with advanced modulation formats (FSK/PSK/APSK).