文章利用耦合波理论研究了光子晶体两平行直波导的定向耦合差频特性, 得出以频率相近的两单频波入射两波导输入端口时, 波导中的光场分布的解析表达式, 并采用时域有限差分法计算了耦合波导中的模场分布。计算结果表明: 通过波导的耦合作用可以在两平行波导中检测到入射波的差频包络, 其时域特性与理论分析相符。提出了利用光子晶体定向耦合波导实现光波-毫米波的转换。

This paper studies the beat frequency characteristics of photonic crystal waveguide directional couplers of the two parallel straight waveguides by using the coupled-mode theory and acquires the analytical expressions for the light intensity distributions in the waveguides when two incident single-frequency waves with similar frequency into the input ports of the two waveguides and calculates the mode field distribution of the coupled waveguides by applying the time-difference time-domain method. The results show that the beat frequency envelope of the incident wave can be detected in the two parallel waveguides by the coupling action of the waveguides and its time-domain characteristics conform to the theoretical analysis. Finally, it presents a frequency transition device for the lightwave to millimeter wave transition by using photonic crystal directional coupled waveguides.