摘要
提出一种光调制器--LiNbO3光纤型行波光调制器,在结构上与传统的LiNbO3波导型调制器不同,它用LiNbO3光纤代替LiNbO3波导传输光载波,衬底则由低介电常数的SiO2取代高介电常数的LiNbO3.采用有限元法对厚的对称电极进行分析,得到调制器微波等效折射率以及等效特征阻抗随电极宽度、厚度、两电极间距以及缓冲层厚度4个参数的变化规律.分析结果表明,与传统LiNbO3波导型调制器相比,LiNbO3光纤型行波光调制器在相速匹配方面表现出极大优越性,若仅考虑相速匹配,理论上可得到高达300 GHz*m的带宽长度积,远大于传统的波导型调制器的1～10GHz*m的限制,彻底解决了一般LiNbO3波导型行波光调制器在相速匹配方面的困难,极大地提高了调制带宽,具有很大的应用前景.
A novel optical modulator, namely LiNbO3 fiber type traveling-wave modulator is proposed. Different from the current LiNbO3 waveguide modulator on the construction, the LiNbO3 fiber in the novel optical modulator was used to replace LiNbO3 waveguide as optical transmission line, and SiO2 with low dielectric constant replaced the high dielectric constant LiNbO3 as the substrate. The finite element method （FEM） was employed to analyze the symmetric electrodes of the modulator. The variation rule of the effective refractive index of microwave and the effective characteristic impedance of modulator related to four parameters including the width, the thickness of electrode, the gap between electrodes as well as the buffer layer thickness was obtained for further research. Analysis results showed that compared with the current LiNbO3 waveguide modulator, the effective refractive index of microwave transmitted on the electrodes was tremendously decreased. As a result,the velocity matching was easier to implement and the modulating bandwidth was greatly expanded. If only the factor of phase velocity matching between optical wave and microwave was considered, a product of bandwidth and modulating length as high as 300 GHz · m, which was much higher than that of the traditional waveguide modulator, could be achieved. The proposed modulator has a great prospect of application in the future.
出处
《天津大学学报（自然科学与工程技术版）》
EI
CAS
CSCD
北大核心
2005年第8期730-734,共5页
Journal of Tianjin University：Science and Technology
基金
天津大学优秀博士基金资助项目(TJ0225).
关键词
LiNbO3晶体光纤
LiNbO3行波光调制器
微波相速
特征阻抗
调制带宽
有限元法
LiNbO3 fibers
LiNbO3 traveling-wave optical modulators
microwave velocity
characteristic impedance
modulating bandwidth
finite element method（FEM）
