新型行波电极超宽带LiNbO_3电光调制器的优化设计

The Design and Optimization of Ultra-broad-band LiNbO3 Electro-optic Modulators of Novel Electrode Structures

采用有限元法和增量电感公式对一种新型电极结构的电光调制器进行了理论分析和设计.计算中对损耗系数进行了修正.计算结果表明这种结构可以灵活地实现相速匹配和有效降低电极损耗.是一种具有超宽带潜力的调制器.用带宽和驱动功率的比值作为衡量调制器特性优劣的标准.得到了这种电极结构的一些优化尺寸.并从中发现适当增大电极间隙有利于提高器件性能.利用优化结果.给出了一带宽为100GHz.半波电压为6V的调制器设计例子.

The characterization and design of LiNbOa optical modulators of novel electrode structures are discussed by using the finite-clement method (FEM) and the incremental inductance formula. Loss coefficients are verified in this paper. The calculation results show that the structures can realize microwave-optical velocity match easily and reduce microwave electrode losses drastically, so the modulators employing such structures are candidate devices for future ultra- high- speed optical fiber transmission systems. The electrode structures are optimized by using the ratio of the 3 dB optical bandwidth to driving power as a standard. The results of optimization show that the properties of the modulators can be improved by increasing the electrode gaps. As an example, an electro-optic modulator, whose bandwidth is 100 GHz, half wave voltage is 6 V and driving power is 0. 48 W, is designed.