基于聚合物光波导垂直耦合器的模式转换与复用研究

发布时间：2018-06-13 00:35

本文选题：光波导 + 聚合物　；参考：《电子科技大学》2017年硕士论文

【摘要】：人们不断开拓新技术来提升单模光纤(Single Mode Fiber,SMF)传输容量,包括密集波分复用、偏振复用以及高阶调制等。然而,随着计算机技术的快速兴起,人们对信息需求量呈现出爆炸式增长。与此同时,单模光纤的传输极限估计在100 Tbps左右。不久的将来,单模光纤满足不了这种信息量增长的需求,因此不得不寻求新技术来进一步提升光传输网络的传输容量。模分复用(Mode Division Multiplexing, MDM)技术便是解决该问题的方案之一。模式复用/解复用器和模式转换器是MDM系统的关键器件。就当前研究而言,模式的转换与复用可以基于光子灯笼、Y分支、长周期光栅以及定向耦合器等波导结构实现。相比较于平面定向耦合器受限于两波导等高的约束,垂直定向耦合器的设计更加灵活。论文基于垂直定向耦合器设计了 LP01-LP21a、LP01-LP21b以及LPo1-LP02模式转换器。由于聚合物材料具有易加工的优点,因此选择EpoCore和EpoClad分别作为芯层和包层制作器件。论文核心内容如下。首先,论文研究了 LP01-LP21a模式转换。运用耦合模理论设计了 LP01-LP21a模式转换器,并运用微加工工艺制作了器件。制作所得的典型LP01-LP21a模式转换器偏振弱相关。TE(TM)偏振在1530 nm波长处达到最佳转换效率达98.2%(94.9%),在C波段随着波长向长波场移动转换效率逐渐下降,在1560 nm波长处降至90.1%(88.8%)。该器件的理论设计参数与实际制作所得器件参数基本上是一致的。其次,论文研究了 LP01-LP02以及LP01-LP21b模式转换。区别于LP01-LP21a模式转换器的设计,由于LP21b和LP02的简并性,不能通过模式间直接耦合的方式实现LP01-LP02以及LP01-LP21b模式转换。论文通过先把LP01耦合到E13,然后通过锥形波导过渡,把E13演变为LP21b或LP02。制作所得的LP01-LP02模式转换器件由于多层结构的应力作用,导致器件偏振相关。TE偏振光实现LP01-LP21b模式转换,TM偏振光实现LP01-LP02模式转换。TE (TM)偏振在1530 nm波长处达到最佳转换效率达98.0% (97.7%),随着波长向长波长移动转换效率急剧下降,在1560 nm波长处降至65.5% (55.5%)。制作所得的LP01-LP21b模式转换器,由于制作所得器件两波导截面尺寸与设计差别较大,模式的相位匹配程度不高,从而导致换效率非常低。
[Abstract]:New technologies have been developed to enhance the transmission capacity of single Mode FiberMode SMFs, including dense wavelength Division Multiplexing, polarization Multiplexing and Higher-order Modulation. However, with the rapid rise of computer technology, the demand for information has increased explosively. At the same time, the transmission limit of single mode fiber is estimated to be about 100 Tbps. In the near future, single-mode optical fiber can not meet the need of increasing the amount of information, so it has to seek new technology to further enhance the transmission capacity of optical transmission networks. Mode Division Multiplexing (MDM) is one of the solutions to this problem. Mode multiplexer / demultiplexer and mode converter are key devices in MDM system. As far as current research is concerned, mode conversion and multiplexing can be realized based on photonic lantern Y branch, long period grating and directional coupler. The design of vertical directional coupler is more flexible than that of plane directional coupler limited by two waveguides. Based on the vertical directional coupler, LP01-LP21aer LP01-LP21b and LPo1-LP02 mode converter are designed. Because polymer materials are easy to process, EpoCore and EpoClad are chosen as core layer and cladding device respectively. The core contents of the thesis are as follows. Firstly, LP01-LP21a mode conversion is studied. The LP01-LP21a mode converter is designed by using the coupled mode theory, and the device is fabricated by micromachining technology. The polarization of the typical LP01-LP21a mode converter with weak polarization correlation has reached the optimum conversion efficiency at 1530 nm. The conversion efficiency of the typical LP01-LP21a mode converter decreases gradually with the wavelength moving to the long wave field at 1560 nm, and the conversion efficiency decreases to 90.1% at 1560 nm. The theoretical design parameters of the device are basically the same as those obtained in practice. Secondly, we study LP01-LP02 and LP01-LP21b mode conversion. Different from the design of LP01-LP21a mode converter, because of the degeneracy of LP21b and LP02, LP01-LP02 and LP01-LP21b mode conversion can not be realized by direct coupling between modes. First, LP01 is coupled to E13, and then through conical waveguide transition, E13 is transformed into LP21b or LP02. The fabricated LP01-LP02 mode conversion device is due to the stress of the multilayer structure. As a result, the polarization-dependent. Te polarizing light can realize LP01-LP21b mode conversion and TM polarization light realize LP01-LP02 mode conversion. The optimum conversion efficiency at 1530 nm is 98.0%, and the conversion efficiency decreases sharply with the shift of wavelength to long wavelength. At the wavelength of 1560 nm, it was reduced to 65.5% and 55.5%. The fabricated LP01-LP21b mode converter is very inefficient because the cross-section size of the two waveguides is different from the design and the phase matching degree of the mode is not high.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

【参考文献】