行波型LiNbO3电光调制器的电极优化设计

利用扩展点匹配方法对厚电极厚缓冲层的共面波导电光调制器的结构和性能参数进行了分析和研究,通过仿真选择合适的电极厚度和缓冲层厚度,所得的特性阻抗和有效折射率与采用保角变换法得到的结果吻合,优化了调制器性能,实现了宽带调制.这一分析方法简便快捷,能够处理电极有一定厚度的多层光波导调制器结构.     

基于铌酸锂薄膜的Y波导集成调制器设计

近年来,基于薄膜铌酸锂（TFLN）平台的高性能电光调制器以其小体积、低能量损耗等特点受到广泛关注。本文提出了一种新的具有垂直电极结构的Y波导铌酸锂薄膜电光调制器。研究了调制器的半波电压与缓冲层厚度之间的关系,优化了Y波导的设计参数,最后设计得到插入损耗<5 dB, 半波电压<1.5 V的高性能调制器。本文不仅为基于TFLN平台的小型化波导的设计和实现提供了思路,而且为制造高性能和多功能的电光调制器提供了实验依据。     

LiNbO3电光强度调制器的进展

介绍了以LiNbO3为基质制作的电光强度调制器的优化电极结构，对电极的几何形状的优化，以及通过对比分析，选择合适的电极厚度和缓冲层厚度进行优化。同时列举了近几年研究LiNbO3电光强度调制器的进展情况。     

高速InP基半导体电光调制器行波电极结构研究

对PIN型和NIN型两种InP基Mach-Zehnder电光调制器的电极结构进行了数值仿真研究,从而确定出适于这两种电光调制器的行波电极结构。仿真结果表明,NIN型电光调制器可采用简单的单臂类微带电极,而PIN型电光调制器需采用周期容性负载电极,以达到良好的阻抗匹配特性和传输特性。进一步地,提出了将串联推挽式行波电极结构应用于PIN型电光调制器,可以简化制作工艺并获得良好的微波特性。     

聚合物共面波导行波电极电光调制器

用聚合物材料BPAN-NT设计并初步成功制作了共面波导(CPW)行波电极电光调制器。用反应离子刻蚀(RIE)的方法制作脊波导,通过电晕极化使芯层有电光效应,利用电镀方法制作厚行波电极。对调制器的各项特性参数进行了测试,测得调制器的微波损耗系数0α=0.9 dB/cm.(GHz)1/2、在1.317μm波长上Vπ=250 V,由此算得芯层材料的电光系数3γ3=3.7 pm/V,同时测得消光比为13.49dB、插入损耗为18.6 dB,在8 GHz的微波频率上观察到了调制光信号,理论计算3 dB光调制带宽为43.77 GHz。     

基于FBG的电光调制器电极设计

电光调制器作为光通信系统中最重要的器件之一,其性能决定了光通信系统的传输性能,而电光调制器的电极结构、种类和设计都对调制器的性能有重要的影响。针对基于光纤布拉格光栅(FBG)的新型电光调制器电极展开了研究和设计,并通过数值计算方法,对模场重叠因子、电极结构参数以及模场重叠因子和FBG中心波长漂移量 的关系做了讨论,并由此对基于FBG的聚合物电光调制器的电极做了一系列的分析和研究。文中的研究对基于FBG的电光调制器的制作具有一定的指导意义,能够促进电光调制器的发展。     

共面波导电极聚合物电光调制器多层结构研究

提出了两种基于共面波导(CPW)电极的多层聚合物电光调制器模型结构,分别为补偿层型结构和屏蔽层型结构。采用了保角变换的计算方法给出了基于CPW电极结构的多层电光调制器的特性参数的计算结果。与传统调制器结构性比较,补偿层型结构能够有效的减小光波与微波传输有效折射率的差,屏蔽层型结构不仅能够减小光波与微波传输有效折射率的差,而且能够通过优化结构参数,有效地消除了微波与光波之间的折射率差,可实现调制信号速率和调制电极阻抗的同时匹配。     

高效微带线聚合物电光调制器的研制

设计、制作并测试了1.55 m 光波长的微带线行波电极电光调制器。如果聚合物材料的电光系数33=30 pm/V,中心电极L 为20 mm,设计的调制器性能参数半波电压为6.70 V。用自主合成的发色团分子组成二阶非线性光学聚合物材料做为芯层制作的聚合物调制器,对调制器的各项性能参数进行了直流、低频和微波性能的测试,采用不同极化方法,在1.55 m 波长上测得低频半波电压分别为10.5 V(电晕极化)和4.9 V(接触极化),折算得芯层材料的电光系数分别为21 pm/V 和45 pm/V。测得消光比为24 dB。用矢量网络分析仪测试电极系统的微波性能,S 参数反映了此电极系统具有低的微波传输损耗和反射损耗。     

电光行波调制器电极特性参量的计算

本文采用简洁的静态求解的方法,考虑了电极厚度和缓冲层对电极特性参量的影响,对四种常用的LiNbO_3光波导行波调制器电极的特性参量进行了分析计算,并得出了一些对设计和优化较有意义的结论。     

光纤聚合物电光调制器电极对波导特性的影响

有机聚合物高速电光调制器是全光纤器件,插入损耗低,集成度高,能极大地降低模式失配和调制电压,提高调制效率,是未来超长距离超大容量高速光通信系统中的关键器件之一。将一种基于长周期光纤光栅的光纤聚合物电光调制器看作5层均匀圆光波导,考虑两层电极及其复折射率的实际情况,利用紧致的超格子方法,在复数域分析这种光纤聚合物电光调制器的波导特性。从模式折射率的实部和虚部、模场分布等角度对数值计算结果进行分析表明,只忽略外电极对调制器的波导特性影响很小,考虑电极时长周期光栅的谐振波长比不考虑电极时大,从而影响调制特性。     

Spectral-domain analysis of coplanar waveguide traveling-waveelectrodes and their applications to Ti:LiNbO3 Mach-Zehnderoptical modulators

Hybrid-mode and quasi-TEM analyses are carried out for coplanar waveguide traveling-wave electrodes applicable to z-cut Ti:LiNbO3 optical modulators. The analyses are based on the spectral-domain approach. The microwave effective index and the characteristic impedance are clarified, together with the microwave conductor loss. These are incorporated to accurately predict the modulator characteristics. It is shown that these characteristics can be greatly improved by employing a thicker buffer layer. High-speed and low-driving-power Ti:LiNbO₃ optical modulators are realized at 1.52 μm wavelength. Agreement between the calculated and measured results is good     

Evaluation of LiNbO/sub 3/ intensity modulator using electrodes buried in buffer layer

For highly efficient operation, a new type LiNbO/sub 3/ Mach-Zehnder intensity modulator using electrodes buried in the buffer layer was designed and fabricated. The modulator was designed considering velocity matching between light and microwave, microwave propagation loss and characteristic impedance Z/sub 0/ of 50 Omega . This modulator for a 1.5 mu m wavelength operates with a V/sub pi / of 3.2 V, a 3 dB down bandwidth of 14 GHz and a temperature dependence of 17 mV/ degrees C.<>     

Low-loss fibre-coupled waveguide directional coupler modulator

We report a fibre-coupled Ti: LiNbO3 directional coupler modulator with total fibre-device-fibre insertion loss as low as 1.5 dB for ?=1.32 ?m. Low loss has been achieved by using diffusion parameters to give good mode match to the fibre and low propagation loss, an effective SiO2 buffer layer to eliminate electrode loading loss and a directional coupler geometry which minimises the effect of bend loss.     

40-Gb/s X-cut LiNbO/sub 3/ optical modulator with two-step back-slot structure

We propose a newly designed X-cut lithium niobate (LiNbO/sub 3/) optical modulator. It has a two-step back-slot structure to satisfy the velocity-matching condition without the buffer layer of silicon dioxide (SiO/sub 2/). Accordingly, this modulator can achieve low drive voltage and low optical insertion loss. In addition, the dc-drift phenomena due to the buffer layer can be suppressed. This structure is fabricated with micromachining technology using excimer laser ablation. The optical 3-dB bandwidth of the fabricated modulator reaches 30 GHz, and the drive voltage is less than 3 V at 1 kHz. From the measurement of the optical eye diagram at 43.5-Gb/s, clear eye openings were obtained. This modulator is sufficient for 40-Gb/s optical transmission systems.     

Optimum design of coplanar waveguide for LiNbO3 opticalmodulator

In this paper, we first present a novel finite element method combined with the conformal mapping (FEM-CM) for a quasi-static analysis of coplanar waveguides (CPW). Using this approach, the optimum CPW structures for the use in the Ti:LiNbO₃ optical modulator are discussed in detail to realize optical-microwave phase velocity match and electrode-source characteristic impedance match. Our numerical results reveal that both conditions can be satisfied simultaneously by introducing a SiO₂ buffer layer and thicker electrodes. The modulator efficiency with respect to the voltage-length product is also evaluated for the optimized structures. Finally, the design guidelines to the optimum CPW structure are presented     

非晶态SiO2过渡层对生长C轴取向LiNbO3薄膜的影响

采用磁控溅射方法,在Si衬底和LiNbO3薄膜之间引入SiO2过渡层制备LiNbO3薄膜。采用X射线衍射（XRD〉、傅里叶变换红外吸收光谱（FT-IR）和扫描电子显微镜（SEM）对LiNbO3薄膜的结晶取向、组成成分和表面形貌进行了表征,重点研究了非晶态SiO2过渡层对LiNbO3薄膜C轴取向的影响。结果表明,非晶态S...     

Double-stub structure for resonant-type optical modulators using 20-/spl mu/m-thick electrode

We propose a resonant-type LiNbO/sub 3/ optical modulator with low halfwave voltage. We optimize the phase constant of the electric wave with thick electrodes to reduce the halfwave voltage. The halfwave voltage of the fabricated modulator with 20-/spl mu/m-thick electrodes is 5.8 V at 10.6 GHz.     

A wide-band and low-driving-power phase modulator employing a Ti:LiNbO/sub 3/ optical waveguide at 1.5 mu m

A wide-band and low-driving-power Ti:LiNbO/sub 3/ optical modulator at 1.5- mu m wavelength is described. A relatively thick SiO/sub 2/ buffer layer is effectively utilized to improve phase velocity mismatch between the microwaves and optical waves. A coplanar waveguide is used as an efficient traveling-wave electrode, and is designed utilizing the upper bound calculation in the spectral domain. Wide-band modulation of 12 GHz (3 dB optical and 6 dB electrical cutoff frequency) and small driving-power-to-modulation-bandwidth ratio of 20 mW/GHz are realized.<>     

X切LiNbO3脊形结构集成电光M-Z型调制器

采用X切LiNbO3 基片 ,设计并研制了脊形结构集成电光Mach Zehnder(M Z)波导调制器 ,实验研制过程包含关键的LiNbO3 基片湿腐蚀刻槽技术和大厚度电极制作技术。研究结果表明 ,脊形结构调制器与传统的平面结构调制器相比 ,在大幅度提高调制带宽方面 ,有着明显的优越性