基于硅基光电子芯片的低损耗动态偏振控制器

Low-loss integrated dynamic polarization controller based on silicon photonics

动态偏振控制器能够实现输入光场任意偏振态到输出光场任意偏振态的控制,可以动态补偿长距离单模光纤导致的双折射效应,是量子通信和相干通信系统中的重要器件.本文设计并实验验证了基于硅基光电子芯片的低损耗动态偏振控制器,芯片采用标准的绝缘体上硅工艺制作,器件整体尺寸为5.20 mm×0.12 mm×0.80 mm,整体损耗为5.7 dB,最大功耗为0.2W.基于可变步长.模拟退火算法、低噪声探测器和高静态消光比的器件,动态偏振消光比可锁定至30 dB以上.芯片采用热相移器对TE0光场的相位延迟量进行控制,整体为0°/45°/0°/45°结构,可实现无端偏振控制.基于Lumerical软件对核心部件偏振旋转分束结构进行了优化,该结构将以端面耦合方式进入波导中的TM0模式光场转化至另一波导中的TE0模式光场,而原单波导中TE0模式光场不发生转化,实验测得动态偏振控制器的静态偏振消光比可达40 dB以上.该器件具有小体积、低功耗和低成本的特点,可以广泛应用于量子通信和相干通信等领域,特别是需要考虑体积、功耗和成本的应用场合.

A dynamic polarization controller(DPC)is an important component in fiber optic communication,optical imaging,and quantum technologies.The DPC can transform any input state of polarization(SOP)into any desired SOP to overcome polarization-related impairments resulting from high internally and externally induced birefringence.In this work,a low-loss silicon photonics-integrated DPC is designed and demonstrated experimentally.The whole chip is fabricated by using industry-standard silicon-on-insulator technology.Using the edge-coupling method,the coupler loss is reduced to less than 2 dB,and the total loss of DPC is reduced to 5.7 dB.Using a variable-step simulated annealing method,for a low-noise photodetector and high-staticextinction-ratio device,a dynamic polarization extinction ratio can reach more than 30 dB.The size of the DPC on the chip is 5.20 mm×0.12 mm×0.80 mm.The DPC utilizes a 0°/45°/0°/45°structure,which can realize arbitrary polarization-based coordinate conversion with endless polarization control.The 0°and 45°transform structures and matrices are presented,and the principle of the 0°and 45°structures is explained in detail by using the Poincarésphere.A simulation using Lumerical is conducted to optimize the polarization rotator-splitter,which can transform the TM0 mode light in one waveguide into the TE0 mode light in the other waveguide while the TE0 mode light in one waveguide remains unchanged.Based on the optimized structure,the static polarization extinction ratio of DPC can be measured to be a value greater than 40 dB.The thermal phase shift(TPS)is characterized by using a Mach-Zehnder modulator.The length of the TPS is 400μm,and the resistance of the metal heater is 2.00 kΩ.The maximum power consumed by the four TPSs is a total of 0.2 W.The modulation bandwidth of the DPC designed by our group is approximately 30 kHz.By considering an applied voltage of 5.6 V in the case of the TPS,the bandwidth-voltage product is 5.6×30=168 kHz·V.To optimize the DPC parameters,such as the step length,electronic noise,and static polarization extinction ratio,numerical simulation results of the simulated annealing approach are analyzed in detail.In conclusion,a low-loss silicon photonics-integrated DPC is designed and demonstrated experimentally.A dynamic polarization extinction ratio is obtained to be greater than 30 dB by using the variable-step simulated annealing method.The DPC is expected to be utilized in fiber or quantum communication systems to minimize size and further decrease costs.