Development of high gain and broadband superconducting booster circuit for optical modulator

研究了一种采用超导电路的LiNbO3光调制器和开关的设计和性能。基于超导共面波导传输线升压电路的新设计方法，利用电磁波模拟器设计了中心频率为10GHz、带宽为5MHz、电压增益为33dB的电压放大器。我们还设计了一种结合光定向耦合器和马赫-曾德尔干涉仪的高速光开关。在MgO衬底上进行了YBCO电极与LiNbO3光波导倒装键合的初步实验。我们利用YBCO薄膜在10[mm]×10[mm]的MgO衬底上制作的曲线形三极切比雪夫滤波器设计升压电路。将MgO衬底上的YBCO电极倒装键合到LiNbO3衬底上的光波导上，并通过冰箱冷却。器件S11（回波损耗）的群延迟观测值与仿真结果的比较。观测到的数据与理论预测的数据基本一致。

The design and performance of a LiNbO3 optical modulator and switch, which employ superconducting circuits, have been studied. Based on a novel design method of the booster circuit using superconducting coplanar waveguide transmission lines, we designed a voltage amplifier with center frequency of 10GHz, bandwidth of 5MHz, and the voltage gain of 33dB using an electromagnetic wave simulator. We also designed a high-speed optical switch combining optical directional coupler and Mach-Zehnder interferometer.A preliminary experiment with YBCO electrode on MgO substrate flip-chip-bonded on LiNbO3 optical waveguide has been made. We designed the booster circuit with the meanderline 3-pole Chebyshev filter fabricated by a YBCO thin film on a MgO substrate with the dimension of 10[mm]×10[mm]. The YBCO electrode on MgO substrate was flip-chip bonded onto an optical waveguide in a LiNbO3 substrate, and was cooled down by a refrigerator. The comparison of the observed group delay of S11 (return loss) of the device and the simulation results. The observed data are in reasonable agreements with those expected from theory.