Linearization of Mach-Zehnder modulator using microring-based all-pass filter

By applying the microring resonator to the Mach-Zehnder (MZ) optical modulator and employing the super-linear phase change characteristic of the all-pass filter, the sublinear modulation curve of the conventional MZ modulator is highly linearized. With properly controlled power coupling between the microring and the arm of the MZ modulator, the third-order distortion can be suppressed. If the transmission coefficient is set between 0.25 and 0.42, the linearity range larger than 90% can be easily achieved. The maximum linearity range is even up to 99.5%.     

具有单一复合调制区的多模干涉效应耦合器 1×3光开关的分析

基于多模干涉自映像原理,分析了一种仅含一个复合调制区的1×3光开关。该开关处于不同工作状态时,调制臂上所加相位调制量之间存在倍数关系,于是可将调制臂上的相移器组合成一个复合调制区,通过连续改变复合调制区的折射率变化量,因此可以将来自任一输入端的光场轮流切换到任意输出端口。以Al0.07Ga0.93As/GaAs脊形波导结构为例,采用BEAMPROP软件,对该开关进行了优化和理论验证。消光比高达30.3 dB;相邻通道之间的串扰低于-29.8 dB;在1.31μm工作波长处约50 nm的波谱范围内,串扰低于-20 dB。该结构可简化传统多通道开关的调制方法,降低外加控制方法的复杂程度。     

多模干涉耦合器一般成像位置分析

自映像效应是多模波导的一个重要特性,利用多模波导自映像效应制成的多模干涉耦合器被广泛地应用于集成光学回路中。然而根据以往的文献要得出多模干涉耦合器的成像位置要经过一系列复杂的计算。根据多模干涉耦合器的自映像原理,对多模干涉耦合器的成像位置进行分析。成像位置与输入场位置和位置数密切相关,给出了成像位置的解析表达式,得出奇数、偶数的位置数的成像位置分别对应相同,并且奇、偶数的位置数所对应的成像位置之和为多模波导宽度的成像规律。用导模传输分析法验证了表达式和成像规律的正确性。根据成像位置的表达式和成像规律可以直接得出任意输入场位置和位置数所对应的成像位置。为一维和二维限制的多模干涉耦合器的设计提供了理论基础。     

S弯曲聚合物热光型可变衰减器的特性

提出一种热光聚合物可变光衰减器(VOA)的设计分析,利用S弯曲的波导提高衰减效率,BPM法模拟中验证其衰减动态范围可达60 dB,实现60 dB的衰减计算功耗为60 mW,附加弯曲损耗小于0.3 dB.并且具有很好的极化独立性,串扰低,尺寸小,易于集成.     

采用接触式极化法研制有机聚合物电光光波导调制器

结合器件的整体结构考虑，对接触式极化方法和工艺进行了研究，基于接触式极化法，设计并制作了聚合物电光光波导相位和偏振调制器。通过测量器件的偏振调制特性，在1550nm光波波长下，获得了最大电光系数为llpm／V，电光相位调制器的半波电压为45V。     

扩展多模波导全内反射型Y分叉开关的分析

利用全内反射和波导理论，分析了多模波导反射区全内反射(Total Internal Reflection，TIR)型光开关的物理模型和降低串音和损耗的原因，给出改进Y分叉全内反射型光开关特征的近似计算方法。数值模拟表明，扩展多模波导的Y分叉全内反射开关的串音和损耗可分别下降15．5dB和0．65dB以上。     

Compact all-optical switches based on photon-induced suppression of mode interference

An optically activated optical switch based on suppression of mode interference (SMI) is presented. The imaging properties of multi-mode interference (MMI) section in the switch with Y-branch can be modified by a controlling light injection. The switch was simulated by finite difference beam propagation method (FD-BPM) and fabricated on GaAlAs/GaAs epitaxial materials. At the wavelength of 1.31 μm, the primary experiment showed an extinction ratio of about 8 dB with controlling light power density of 73.5 W/mm2.     

A novel coupled quantum well structure with large field-induced refractive index change and low absorption loss at 1.55 μm

In future networks, very-high-speed and high-capacity di-rect optical switching systems will play a very importantrole, and an optical switching device is considered to be akey device for the construction of such high-speed opticalswitching systems or photonic integrated circuits[1]. Soit is imperative for optical switching device to search fora material with high-speed and large field-induced re-fractive index change in the case of low absorption loss.It is well known that a large electric fi…     

基于绝缘体上硅的一种改进的Mach-Zehnder声光调制器

传统的基于绝缘体上硅的Mach-Zehnder(MZ)声光调制器中,叉指换能器位于两臂的同一侧.为实现高的调制效率,声表面波的波峰和波谷分别调制MZ干涉仪的两臂,这要求控制MZ干涉仪两臂之间的距离为奇数倍声波半波长.但实际上由于传播过程中衬底材料的变化,声波波长会变大,这会导致两臂的间距难以准确设置.另一方面,声波在传播过程中经过MZ干涉仪的一臂后会发生衰减,降低了对另一臂的调制效果,影响了整体的调制效率.本文针对这些问题给出了一种解决方案,把叉指换能器放在MZ波导两臂之间,确保MZ干涉仪两臂到叉指电极中心距离相等.采用有限元法,首先对新提出的结构进行分析,然后通过声光互作用原理得到了材料的折射率变化;进而研究了波导类型、波导宽度、氧化锌厚度及叉指对数等因素对声光调制效率的影响,并对声光调制器的结构参数进行了优化以提高其性能.基于COMSOL Multiphysics的仿真结果表明,当条波导宽度为6μm,氧化锌只覆盖有叉指电极的部分且厚度为2.2μm,控制叉指电极数目为50对时,波导有效折射率变化在驱动电压为1 V时可以达到4.08×10~(-4),比传统结构提高了12%.     

Compact design of 1×16 cascaded Y-branch splitter

We proposed a new kind of cascade Y-branch splitter with a branching region and a fan-out region. The length of the new device are analyzed in detail and compared with ordinary ones. The results show that the new splitter can be 10%-30% shorter than the ordinary splitters. We designed and fabricated a 1×16 splitter in K+/Na+ ion-exchanged BK7 glass. The length of the new designed splitter is 30-mm, which is 85% of the length of an ordinary splitter.